Airplanes Unexpectedly Modify Weather

reillymj writes "Commercial airliners have a strange ability to create rain and snow when they fly through certain clouds. Scientists have known for some time that planes can make outlandish 'hole-punch' and 'canal' features in clouds. A new study has found that these odd formations are in fact evidence that planes are seeding clouds and changing local weather patterns as they fly through. In one case, researchers noted that a plane triggered several inches of snowfall directly beneath its flight path."

Comments

What wasn't mentioned

[mlawrence]

Was this plane belonged to the Mexican Cocaine Cartels, who thought they were being trailed.

Re:What wasn't mentioned

[Anonymous Coward]

Dude! This is pure snow! Do you have any idea how much this mountain is worth?

Cloud Seeding

[illumastorm]

Interesting. So the effect of cloud seeding is just as likely to be caused by the planes flying through the clouds rather than the silver iodide alone?

Re:Cloud Seeding

[Trepidity]

That was suggested back in 1970--- that cloud seeding experiments need to consider the possibility that the plane's flight itself is doing the seeding.

Re:Cloud Seeding

[Kral_Blbec]

Its a matter of distribution and degree. Just a plane might be enough to start off what was almost rain in a area near its flight path, but theoreticly silver seeding would generate rain where it was unlikely and over a wider area that just directly below.

Re:Cloud Seeding

[bunratty]

I would think anyone who understands how to design experiments would see the need for a proper control group. If you fly a plane through some clouds and dump iodide crystals, and don't fly any plane though other clouds, what caused the difference in precipitation? Was it the plane or the iodide crystals? Didn't they carry out such a proper experiment?

Re:Cloud Seeding

[Smauler]

Control groups are basically impossible to find with clouds, as any meteoroligist will tell you. We still cannot absolutely predict which ones will dump rain on us, and which ones won't - often they behave in completely unexpected ways with no apparent reason why. There's no such thing as a control group with clouds, because one formation may have been going to dump a load of rain anyway, and another seemingly identical formation would not.

With a large enough control it may be possible - but getting a large control is basically nigh on impossible because of differing air temperature, atmospheric pressure, wind speed, and a whole host of other variables. This is not something you can accurately simulate either.

Re:Cloud Seeding

[bunratty]

[citation needed]. You can easily find a control group. Simply randomly assign individuals of the population to the control group or the experimental group. This is done with people in drug trials all the time, and I would submit that people are even less predictable than clouds.

Re:Cloud Seeding

[Motard]

Didn't we have this sort of thing after 9/11? I seem to recall a /. submission about observed weather changes while all the aircraft were grounded.

Re:Cloud Seeding

[apoc.famine]

Sorry, but you don't know what you're talking about. There is no possible way to do any sort of control on clouds. They are all different. Trust me - I'm slogging my way through meteorology classes at the moment. I took a class that touched on cloud physics last fall.

Clouds are substantially different, and waaaaay more complicated than human physiology. We're not at the stage that we can measure the amount of water and particle sizes in clouds yet. The best we can do is fly a 3cm diameter probe through a cloud, and sample something like a millionth of it.

In fact, cloud dynamics are so ridiculously complicated that we don't even have good models for them yet. Supercomputer time sort-of gets us close to working models. The fact that nobody can reliably predict rain and snowfall amounts, nor weather more than a week out should give you some indication of the complexity of clouds.

Re:Cloud Seeding

[bunratty]

Yes, I do understand that clouds are all different. You simply randomly assign clouds to a control group or an experimental group. That's how you get controls. It doesn't matter how complicated clouds are -- it is trivial to get a control group. You don't seem to understand how to design controlled experiments. Please, provide a citation stating that it's impossible to perform controlled experiments on clouds, preferably with a lucid explanation for why it is so.

Re:Cloud Seeding

[Anonymous Coward]

Should you not then simply consider the groups to be of planes rather than clouds? If you fly 200 planes through 200 clouds, 100 of which try to actively seed the cloud somehow and the other 100 just fly through without doing anything special, you should be able to tell if there's a difference.

Then again, IANAM.

Re:Cloud Seeding

[commodore64_love]

So conspiracy nut Alex Jones was right after all. The high-flying planes are changing our weather.

Re:Cloud Seeding

[bunratty]

That's exactly the way it seems to me, too. Of course, it could be that clouds have a high degree of natural variability, and the effect of cloud seeding may be small, so it could take a very large number of experiments to demonstrate a statistically significant effect for cloud seeding. But that's a different statement altogether from saying that it's impossible to get a control group with clouds, which seems preposterous to me. You get control groups with random assignment, as you explain.

Re:Cloud Seeding

[apoc.famine]

I know you think you're very smart. But you really don't understand how different clouds are, or you don't understand what a control group is.

If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.

This is the case with clouds.

If you'd like to know more, try Wallace and Hobbs. It's one of the cornerstones of modern atmospheric science. I know you're all hip and can make fancy [citation needed] fake-wiki code, but there are some subjects you can't be an expert on just by casually reading a page on the internet. Neurosurgery and cloud microphysics are two of those things.

Cheers!

Re:Cloud Seeding

[Anonymous Coward]

I think the guy you are arguing with is thinking of an experiment something like this, for example. Take 1000 clouds that are at least reasonably able to produce precipitation (for instance cumulus congestus clouds, or only nimbo stratus). As the cloud appears, draw a color out of a hat. If blue, seed the cloud, if red, fly through the cloud, and if green do nothing. If 90% of the seeded clouds produce precipitation, and only 40% of the unseeded clouds do, then that is good evidence that the seeding has worked, no matter what all of the variables are. This concept is called blocking in designed experiments and can be very effective.

An easier to understand example is this. I'm testing leather A and B for shoe construction. How people use shoes is dependent on many variables, you might have violin players and rugby players using the shoes. One can't possibly design an experiment to account for all the variables, unless you randomly assign one member from a pair of shoe to have use leather A, and the other one leather B. That way each person is testing both leathers under presumably the same circumstances.

The cloud example is not nearly as efficient as the leather example above... it would take a lot more data for me to believe that seeding works, but it is an effective experimental strategy, no matter how complicated cloud physics is. My gut feeling is that the effect of seeding is small, so it would take a tremendous number of runs to be sure of the results. But if the experiment is run a thousand times, and each time seeded clouds produce more rain, don't you think that's a possible indication that the seeding works? One doesn't have to understand everything about a cloud to experiment with them, as in any field.

And yes, I'd reckon the person you are arguing with understands both what a control group is, and how different clouds are.

Re:Cloud Seeding

[Billly Gates]

Unfortunately there is no proof that an external event or condition created the statistical and mathematical variations in the results of the experiment. The conditions can be different clouds, temperature, humidity, and other atmospheric conditions. Academically the clouds and atmospheric conditions have to be and I emphasize have to be identical in the control group to be considered valid. There is no way around it. You can run an expensive experiment yourself but the experts will reject it because there is no proof that the planes, heat, change in pressure, wind, or iodine caused the precipitation. It could be anything?

Running a plane is expensive and since it can not be proved then no one will want to fund it.

Re:Cloud Seeding

[chaboud]

Despite the largely chaotic nature of cloud formations (and, thus, the difficulty in modelling behavior), we know that certain inputs, situations, and characteristics have a higher likelihood to lead to expected behaviors than others. It's how we can have hurricane season, make reasonable predictions about precipitation much of the time, etc.

Additionally, weather prediction a week out is a significantly different problem (having to do with predicting the global weather system instead of a comparatively local one) than rainfall prediction tomorrow.

Statistically, of course it is possible to conduct an experiment with a control group (or groups) and draw statistical inferences about the effects of different approaches to cloud-seeding.

We draw localized inferences from economic datasets of enormous magnitude, with many unrecorded inputs. To suggest that we can't draw reasonable inferences through large-scale statistical studies of cloud-seeding suggests a superstition about complexity and chaos indicative of your needing to finish more than just your meteorology classes before you make decrees about what we, as scientists can't do.

Suggesting that "there is no possible way to do any sort" of anything is typically a mistake. If you start a sentence like that, you should end it early.

Re:Cloud Seeding

[Graff]

If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.

You can still use that data as a control, you just need to properly categorize the data before you use it. Coming back to cloud formations and controls what you'd need to do is classify each cloud, control or not, and then use the data appropriately.

Observe the type of cloud, the meteorologic conditions, and other pertinent data such as season, phase of the moon, natives chanting on the ground, whatever. You then compare your clouds that have been seeded against appropriate control clouds. Yes, this means you will need to either get a lot more data or just limit the clouds you pick to certain conditions and types. Meteorological research is slow, painstaking, and time-consuming because your laboratory doesn't fit into a building and you have to do a lot more work to properly isolate all variables.a

Re:Cloud Seeding

[sexconker]

I would think anyone who understands how to design experiments would see the need for a proper control group.

We've already seen that no one who understands how to design experiments has anything to do with the study of weather or climate.

Re:Cloud Seeding

[sexconker]

Sorry, but you don't know what you're talking about. There is no possible way to do any sort of control on clouds. They are all different. Trust me - I'm slogging my way through meteorology classes at the moment. I took a class that touched on cloud physics last fall.

Clouds are substantially different, and waaaaay more complicated than human physiology. We're not at the stage that we can measure the amount of water and particle sizes in clouds yet. The best we can do is fly a 3cm diameter probe through a cloud, and sample something like a millionth of it.

You simply need to randomly assign members of the sample size to the test and control group and then compare the results. Repeat until you have a large enough sample size to draw conclusions or design better experiments.

And humans are a tad bit more complex than clouds, I think.

You are an idiot. It comes as no surprise that someone with so little knowledge of the scientific method and/or statistics is well on his way to becoming a "climate scientist".

Re:Cloud Seeding

[Anonymous Coward]

So if I test the lures, and the first lure attracts some sort of swimming animal within 15 minutes 90% of the time, and the second lure attracts some sort of swimming animal within 15 minutes 10% of the time, I can't gain any knowledge about the effectiveness of the lures from this experiment? Methinks you might have trouble producing results in your field. You should probably stick to numerical modeling or theoretical exercises if you continue this kind of attitude towards experiments and "control groups".

Re:Cloud Seeding

[Anonymous Coward]

You are an idiot. It comes as no surprise that someone with so little knowledge of the scientific method and/or statistics is well on his way to becoming a "climate scientist".

I think this is unfair. This guy definitely needs some training with statistics and experimental design / scientific method, but to propose that he is representative of "climate scientists" is a result of your own misunderstandings in the field of climatology. Unless you think Al Gore is a "climate scientist", in which case it is a result of your misunderstandings in the field of knowing what a scientist is.

Re:Cloud Seeding

[chaboud]

You need to read up on the scientific method (and wikipedia is fine: here). Control groups, as indicated by their name, are statistical instruments that are, by definition, not identical. They can be practically identical, for the purposes of the experiment.

If we were to take your apparent view of science, nothing in the history of scientific inquiry would have been sufficiently proven, as it is highly unlikely that quantum spin characteristics met the burden of having to be identical in the controls of chemical experiments, or that Galileo's balls met the burden of having to be identical except for their mass.

Read up on controls here...

Statistical controls via randomization are an accepted (and fundamentally sound) approach to the reduction of experimental measurement error. Something being very complex doesn't make it unobservably complex. The assertion is so absurd that it is either a troll or a genuine failure to understand the scalability of reason, causality, and the scientific method.

Re:Cloud Seeding

[bunratty]

If I were going to test a fishing lure, say a worm, I would test it against some other lure, say a small fish. If I caught twice as many trout with the worm than with the small fish, could I not say that the worm is the more effective lure?

If I picked 200 clouds to fly through, and randomly sprinkled iodide crystals in 100 of them and randomly sprinkled salt crystals in the other 100, and the ones sprinkled with iodide crystals produced twice as much rain, could I not say that the iodide crystals are effective at seeding clouds? Why is it that you say it's "impossible to pick a control group"? It's just using a random generator!

It's not a matter of whether I think I'm smart. Understanding how to create controlled experiments is just not that hard.

Re:Cloud Seeding

[bunratty]

Yes, exactly. You could perform the test on cumulus clouds, on stratus clouds, on cirrus clouds, and on nimbus clouds. Just come up with a criterion for which clouds to try your experiment on, then randomly assign some clouds to a control group and the rest to the experimental group. Just like every other control experiment ever performed. What is it about the scientific method that's so difficult for so many to understand?

Re:Cloud Seeding

[harlows_monkeys]

Sorry, but you don't know what you're talking about. There is no possible way to do any sort of control on clouds. They are all different. Trust me - I'm slogging my way through meteorology classes at the moment. I took a class that touched on cloud physics last fall

Pick 1000 clouds. Randomly assign them to two groups. Try cloud seeding in one of the groups. Fly identical airplanes through the other, going through the motions of cloud seeding, but not actually seeding. Observe results. Apply standard statistical tests of significance to see if there was a meaningful difference in rainfall from the two groups of clouds.

Why would you think the complexity of clouds precludes doing a controlled experiment?

Re:Cloud Seeding

[apoc.famine]

The issue is that those 200 clouds would all be different. And you'd probably never find another one like any one of them. In fact, it's likely that you'll find a bunch of different conditions within all those clouds.

That doesn't help you down the line. We can't even tell what cloud properties are like without flying a plane through the cloud. And when we do, two things happen: First, we change the cloud around the plane. Second, we're only sampling a tiny part of the cloud.

Statistics start to fall down when you have a nearly infinite number of choices, and no ability to make use of the statistics. And by that I mean that even knowing what conditions statistically are good for cloud seeding, the only way to find out if they are occurring is to fly a plane through the cloud and sample it. That doesn't really help, since there's no predictive ability.

And the worst part? Rainfall is so variable that the statistics would be nearly impossible. I'm guessing you'd need far more than 100 tries to get anywhere. Even across a square mile you'll often find rainfall differences in excess of 100%. Where do you sample? How do you ensure that you got an accurate measure of rainfall? If you set out a rain gauge, and all the rain fell the mile before it got to it, you've got useless data.

Mix high internal variability, with high spatial variability, and an inability for us to measure almost any part, and you've got something pretty impossible to do a controlled study on.

Re:Cloud Seeding

[apoc.famine]

Here's my reasoning from another reply.

Re:Cloud Seeding

[eonlabs]

I'm more surprised this is surprising.
Think about it from a surface area perspective. More surface area, more room for condensation, greater chance of precipitation I'd suspect.

Re:Cloud Seeding

[Anonymous Coward]

In reality, the effect of cloud seeding is probably very small, in fact the inconclusiveness of studies up to this point is a good indication of that. But lets say that a new method of cloud seeding is developed. You're saying we can't test if it is effective or not, because we don't understand all of the intricacies of clouds. So every time a large cumulus cloud forms (pick a size to start with), randomly decide to treat it, or not treat it (the control). And let's say in this hypothetical situation that the data is as follows. Treatment: 100% chance of precipitation production. Control: 10% chance of precipitation. If there are 500 samples to each group, are you really saying that this experiment has no value, and that the effectiveness of this new cloud seeding procedure hasn't been demonstrated? Come on. And the problems of measuring rainfall have nothing to do with this discussion. If the effect size is large, then the data would clearly show that (nobody's suggesting that you take a rain measurement from one location). And you say that only airplanes can get information about clouds, and that's just wrong. Ever heard of radar? Radiosondes? We all know that performing this experiment wouldn't be cheap, but your assertion that it's impossible to set up an experiment with clouds is just wrong

Re:Cloud Seeding

[Anonymous Coward]

In reality, the effect of cloud seeding is probably very small, in fact the inconclusiveness of studies up to this point is a good indication of that. But lets say that a new method of cloud seeding is developed. You're saying we can't test if it is effective or not, because we don't understand all of the intricacies of clouds. So every time a large cumulus cloud forms (pick a size to start with), randomly decide to treat it, or not treat it (the control). And let's say in this hypothetical situation that the data is as follows. Treatment: 100% chance of precipitation production. Control: 10% chance of precipitation. If there are 500 samples to each group, are you really saying that this experiment has no value, and that the effectiveness of this new cloud seeding procedure hasn't been demonstrated? Come on. And the problems of measuring rainfall have nothing to do with this discussion. If the effect size is large, then the data would clearly show that (nobody's suggesting that you take a rain measurement from one location). And you say that only airplanes can get information about clouds, and that's just wrong. Ever heard of radar? Radiosondes? We all know that performing this experiment wouldn't be cheap, but your assertion that it's impossible to set up an experiment with clouds is just wrong

Re:Cloud Seeding

[Runaway1956]

"cloud dynamics are so ridiculously complicated that we don't even have good models for them yet"

You should get Al Gore and company to help you. FFS, they've had good working climatology models for decades now, complete with hockey stick projections! (Lest any particularly dense readers mistake the sarcasm, any time I refer to Al Gore, I use it as a synonym for "douchebag")

Re:Cloud Seeding

[lightversusdark]

This doesn't surprise me at all. I live near Heathrow in London, and the best weather so far this year was while the airports had grounded flights due to the Icelandic volcanic ash. Many of my friends commented on the coincidence.

Re:Cloud Seeding

[bunratty]

Yes, I agree that the 200 clouds will all be different. Nonetheless, if you randomly assign 100 clouds to one group and the other 100 to another group, then add up the precipitation totals of the two groups, the totals should be approximately equal. Even though the individual clouds are different, the law of large numbers says that the larger the sample of clouds, the lower the standard deviation of the sample will be. This is basic statistics.

If you then seed one group of clouds and not the other group, and you observe that the seeded group produces much more precipitation than the control group, you would then conclude that cloud seeding works. That the clouds are all different makes no difference, just as it makes no difference that all the people in a clinical drug trial are all different. You may understand meteorology, but you don't understand statistics and controlled experiments.

Re:Cloud Seeding

[FiloEleven]

It seems to me that the issue lies in the extremely broad cloud classifications--this comes not from any training but from reading apoc.famine's posts. If you visualize words like 'cirrus,' 'nimbus,' and 'stratus' to be categories for clouds similar to the rock categories 'igneous,' 'metamorphic,' and 'sedimentary,' and then think of the extremely varied characteristics of rocks within each category, and finally imagine that instead of flying a plane through cloud we are hitting rocks with a hammer and chisel to see how they split, you can grasp the potential for so many unknowns as to make the experiment worthless.

I don't know how well metaphor holds, as I said this is just inference, but I don't think it an absurd possibility that we know less about cloud behavior than the layman would believe.

Re:Cloud Seeding

[ffreeloader]

Nope. You can't. You can use the same lure on the same fish under identical conditions and get fish to respond 90% of the time on day one, and on day two fish will respond to the same lure, fished the same way, 10% of the time.

If fishing was as predictable as you think it is, it would be called catching, not fishing. There's a reason most fishermen who use lures have a large tackle box with a good selection of lures. What works one day will not attract a single fish the next day. The same goes for fly fishing. There's a reason a good fly fisherman will have a large variety of flies. What works one day won't work the next.

I fished streams for years, and yes, some lures or baits worked better than others, as in on more days than other lures/bait, but if I had fished only one bait or one lure every time I went out fishing I would have gotten skunked a whole lot more than I did.

I was a pretty good at stream fishing too, as the Umatilla and Nez Perce Indians I used to fish with on a regular basis used to call me "The Great White Fisherman" as I'd go home with my limit when they were going home skunked. I rarely went home skunked, but I used a large variety of bait and lures, and could picture in my head where fish would be holding.

Re:Cloud Seeding

[bunratty]

There is certainly potential for the experiment to not produce significant results. But there's no reason to believe that we would somehow not be able to make a control group for clouds. To take your example for rocks, you could test the effectiveness of different hammers on breaking rocks.

Let's say we want to test how well a steel hammer compares with a rubber mallet for breaking rocks. We have a pile of 200 assorted igneous rocks, all different. We randomly split these 200 rocks into two piles of 100 rocks each. Even though the rocks may be complicated and all different from each other, the distribution of the properties of the two groups of rocks will be similar. If strike the rocks in one pile with a steel hammer and we strike the rocks in the other pile with a rubber mallet, and the steel hammer breaks 50 rocks and the rubber mallet breaks 25 rocks, why wouldn't we be able to conclude that the steel hammer is better able to break igneous rocks?

Why would the fact that the rocks are all different mean that we would not be able to make a control group?

Re:Cloud Seeding

[bunratty]

I agree that fish can behave differently on different days. This is why we repeat experiments instead of taking the results of one experiment as conclusive. Are you seriously saying that if when I use lure A I consistently catch twice as many fish as lure B, I still cannot say that lure A is more effective?

How about if when I give Tylenol to test subjects with headaches, 50% report improvement, vs. 20% for a placebo? Can we not conclude anything about the effectiveness of Tylenol, just because each of the subjects is different and headaches just go away naturally?

Re:Cloud Seeding

[tsm_sf]

We draw localized inferences from economic datasets of enormous magnitude, with many unrecorded inputs. To suggest that we can't draw reasonable inferences through large-scale statistical studies of cloud-seeding suggests a superstition about complexity and chaos indicative of your needing to finish more than just your meteorology classes before you make decrees about what we, as scientists can't do.

He seems to be saying that our understanding of clouds hasn't progressed far enough to even begin something like this. You seem to be saying that economists are scientists. One of you has a problem.

Re:Cloud Seeding

[DutchUncle]

There was a *lot* of stuff written about differences in weather patterns after the 9/11 flight ban. Satellite pictures showed distinct differences.

Re:Cloud Seeding

[bunratty]

I don't need to be an expert on meteorology to know how to perform controlled experiments on cloud seeding, just as I do not need to know about physiology to know how to perform a controlled experiment on drugs. The scientific method is far easier than you're making it out to be. Talk to your professors about it on Monday.

Re:Cloud Seeding

[Anonymous Coward]

I'd think a climate scientist would have a deep understanding of statistics and statistical design of experiments. I think we need a larger sample size of climate scientists to draw any conclusions, but maybe lack of this understanding is why they are so terrible at telling me if it will rain tomorrow or not?

Re:Cloud Seeding

[The_Wilschon]

I'm very glad that you've taken classes, and I'm even more glad that you're taking obviously quite a lot of time to think about this. However, as a working scientist (HEP) myself, I have to assert that you are quite wrong. Take a large number of clouds. Fly a plane through each one of them, half of the time dropping cloud seeding crystals, half of the time not (choose by flipping a coin). Fill two histograms with the integrated radar echo strength, beginning from the moment the pilot reports entering the cloud, and ending with the time the cloud ceases to precipitate, or one hour later, or some such. Obviously, put the data from the seeding runs in one histogram, and the data from the non-seeding runs in the other. At this point, you have obtained approximations to two distributions. You can obtain error bars on each bin of each histogram (poisson statistics), and estimate systematic errors on top (in quadrature) of those. Now, you can do a K-S test, or a Chi-squared test, or an eyeball test, and determine whether the two distributions are commensurate within experimental error or not. Quote Bayesian credibility, or confidence levels, or whatnot. Done. You have a successful experiment and a publication.

The key to the experiment is that the set of all clouds has some (currently unknown, but definitely fixed) distribution of rainfall amounts. As you draw samples from this distribution and fill a histogram, you get an idea (perhaps fairly coarse) of what that distribution is. Then you draw samples from a different distribution (seeded clouds), and get an idea of what that distribution is, too. Do these distributions appear to be different, or are they similar enough that we can't tell? Since what matters is the distribution as a whole, we don't need to worry about matched pairs in control and experimental groups, or what the characteristics of individual clouds are. Trust me, we have exactly the same situation in HEP. No two collisions are ever exactly (or really even close to exactly) alike, so if matched pairs were required, we'd never get anywhere at all.

The kicker is, of course, getting enough samples to populate your histograms sufficiently to get a good enough idea of the distributions. You are asserting that there are too many variables in cloud configuration space (and you're right, there certainly are an awful lot). But we don't care about filling up cloud configuration space. What we care about is filling up integrated radar echo (as an approximation to rainfall amount) space, which is one dimensional, and therefore much, much easier to populate.

Re:Cloud Seeding

[The_Wilschon]

I know you think you're very smart. But you really don't understand how different clouds are, or you don't understand what a control group is.

Just a bit of advice, as a scientist to a soon-to-be scientist: Try to be a bit more gracious in telling people that they are wrong. Telling people they are wrong is very important, and you should not shy away from it very often, but being even a little bit of jerk about it (and you are really being quite a lot of a jerk here) is not going to help. All that that will do is get you a reputation for being pompous and difficult to work with, which can push collaborators and funding to others.

Re:Cloud Seeding

[ffreeloader]

Yes. That's exactly what I'm telling you. You could be fishing lure B in the wrong places, under the wrong lighting and/or water conditions, in the wrong manner, or even using the wrong color of lure. In fact, I've known of lures that were absolute killer lures in one body of water, and worked anywhere from very poorly to okay where ever else I ever used them.

I fished a lake in northwestern Montana that had the nicest Cutthroat trout I've ever seen. But, you had to have local knowledge to fish it as there was only one way to catch them. You had to pack a canoe in a half mile and then troll the lake by paddling the canoe, as no motors were allowed, at the right time of day with a certain spinner. With it you would catch 6-8 lb cutthroat, and with anything else you went home skunked. That same lure worked okay in other places but it wasn't the killer lure it was in that particular lake. I got skunked on that lake quite a few times before one of my parent's neighbors took pity on me and told me how to catch them. I'd have never figured it out on my own as I didn't live there and couldn't fish the lake on a regular/daily basis and I was far better at stream fishing than lake fishing.

 

Re:Cloud Seeding

[bunratty]

Yes, you are correct that you could be using lure B in the wrong places, if you use lure A in one place and use lure B in another. That's why one would not perform the experiment in this manner. Which is the variable causing the difference in catches? Is it the lure, or the location? If you use both lures in the same location, surely you will be able to tell if one is much more effective than the other. That's how science has been done for hundreds of years. It's the scientific method.

Re:Cloud Seeding

[bunratty]

He's even chosen me as a Slashdot foe (he's listed as one of my freaks). I'm honored!

Re:Cloud Seeding

[shadowbearer]

The cloud example is not nearly as efficient as the leather example above...

  That is where your analogies fail in this context. "Efficient". The universe cares not about efficiency; efficiency is a human invention. A good example of that dystopia is the debate over the 'design' of the eye.

  Your analogy might make sense if you could find 1000 clouds that had some overall structure in common other than the basic small scale physics.

SB

Re:Cloud Seeding

[Anonymous Coward]

The scientific method is also a human invention, with which the universe cares nothing about. "Efficiency" probably wasn't the best word. I was trying to describe the fact that a smaller sample size testing the leather would be sufficient over the case of the clouds - the variability of clouds being the reason for this. I will admit that you may be making a good point, and I'm just missing it (especially the dystopia / eye part).

Re:Cloud Seeding

[Anonymous Coward]

In addition to Bunratty's comments, why not switch between lures each time, or run both at the same time (probably not for fly fishing though). I didn't say you would have to test them on different days. That would be a terrible experimental design, for the reasons you cite. And your comments about requiring different lures for different conditions is interesting. In this case the results obtained from my experiment would only apply to those particular conditions, but the experiment can still be done. The next day, under different conditions, test both lures again. Repeat. If 90 out of 100 days lure B works statistically better than A, wouldn't you choose lure B? And if you take good data, you might be able to find that factor that makes lure A better (e.g. it was raining those ten days). In the cloud example, there is lots of data that can be taken during the study, and in addition to having a varies distribution of treatment and control clouds, one might be able to find other factors that affect the outcome of the experiment.

Re:Cloud Seeding

[Anonymous Coward]

Climatologists don't spend much time trying to figure out if it's going to rain the next day. That's the meteorologists job (and everybody complains that they do a bad job, but they're always interested in what they have to say - weird). The climatologist wants to figure out how the climate of a region will change, what factors are most important for determining that change. Milankovitch cycles, the amount and type of clouds in the atmosphere, changes in solar output, ocean currents, greenhouse gases such as water, methane, and carbon dioxide... how do these variables affect the climate of a region. That is what the climatologist is interested in figuring out.

Re:Cloud Seeding

[shadowbearer]

  The scientific method is also a human invention, with which the universe cares nothing about.

  But humans do, and that's how we've managed to invent the technology that allows us to debate this on this forum.

  I don't enjoy being baited, but I'll answer. You might get more than you bargained for.

  Your leather analogy fails because there is a limited sample to draw the data from, in comparison. Even amongst seven billion human beings there is a fairly small number of finite combinations that create the demand for the various sizes of leather; we are all built more or less in the same framework in a physical sense. Put simply, leatherwork is a human technology built on demand - the universe didn't invent it.

  Clouds aren't - the variables there are at least several orders of magnitude more complicated on local scales. One cumuli isn't remotely like another cumuli. That's not only why we can't predict storms, but why we can't say why one cloud is different from another cloud. If we could model reality on that level then we'd all be living within computer simulations - at least then we could make it all work the way we want... you don't do much cloud watching, do you?

  The dystopia/eye part was sarcastic commentary on a large part of human society's continuing stubborn refusal to accept that it wasn't created by some superstitious entities' whim but rather from basic physical processes that had very large amounts of time to act; in other words, that part of what you said sounds like creationism, and it pushes some of my bullshit buttons.

  We as a species should not lie to ourselves - and, especially in our technological age - that we have all the answers. That does not mean that we should accept simple answers because they make us feel good.

  If you intend to spin this into global climate change argument, I'm game, but be aware that I work for a living and can't respond immediately.

  Call me arrogant, call me whatever, I don't give much of a fuck anymore.

  SB

 

Re:Cloud Seeding

[bunratty]

Academically the clouds and atmospheric conditions have to be and I emphasize have to be identical in the control group to be considered valid.

Why? And, if so, how can you apply the scientific method to a clinical drug trial? According to your reasoning, you cannot perform clinical drug trials, because you cannot possibly give a placebo and the drug to identical people with identical conditions.

Re:Cloud Seeding

[Billly Gates]

"it is highly unlikely that quantum spin characteristics met the burden of having to be identical in the controls of chemical experiment"

Funny you picked quantum mechanics. Many scientist reject the theories because they can not be proven and it took decades before anyone took it seriously. Most scientists are hypocrites in this area as a result.

Statistical variation from randomization does not equal changing the experiments variables (not statistical). Variations that are accepted statistically in a scientific method are only considered if the conditions are identical. Have you written any papers at a masters or PHD level before?

I had a friend who compared writing his dissertation to proving there is not an invisible pink bunny rabbit skewing results of his data.

How can you prove that an airplane created precipitation of the clouds, atmospheric conditions, and humidity are different? You can't.

Re:Cloud Seeding

[TapeCutter]

"The issue is that those 200 clouds would all be different."

It's NOT an issue, if they are split randomly into two groups then the statistical expectation is that roughly the same number of clouds in each group will produce rain. You then treat one group of clouds and leave the other alone (the control). If the number of clouds that produce rain in the treated group is significantly different to the control group then the treament has had an effect on rain production.

This is all just bog-standard statistical analysis.

Re:Cloud Seeding

[chaboud]

I'm saying that, statistically, we can draw inferences from datasets without understanding and isolating the causal and even contributory natures of the system that we are examining. We need to take care to not reach too far in our conclusions, but random control group selection is an absolutely scientific (and reasonable) approach to attempting to experimentally measure the effectiveness of a single differentiating action. And I never said that economists are scientists.

The argument appears to be:

We can create a control group for cloud seeding...

Well, there's this one other thing that *might* be the cause, making it harder to isolate...

That's okay, because we can control for that...

Okay, but there's one more thing...

Look, statistically, we can control for that, and, given a sufficiently sized sample set, for a broad range of variables...

My brain hurts... But there's one more thing...

You're not listening...

Regression is the essence of statistics. Fail to understand it at your own peril. On slashdot, it just makes you look stupid. In the scientific community, failure to understand regression can make you look jobless.

Re:Cloud Seeding

[Anonymous Coward]

Yet, despite living creatures being "all different", we still do statistical analysis on the effect of several factors on them (see "Biology").

Read a bit on "Experimental design", "Stratified sampling" and "Randomized controlled trials" and THEN you can start to understand why you can do statistical analysis even when the population is heterogeneous.

Also, it's trivial to find a counterexample to what you're stating. Here's a paper on the statistical analysis of cloud turbulence (even though there are no two identical clouds): http://adsabs.harvard.edu/full/1994ApJ...429..645M

Re:Cloud Seeding

[MoeDumb]

This doesn't even touch those high flying planes criss-crossing the morning skies with chemtrails which dissipate over several hours and eventually fall to earth. God only knows what they are doing to the weather, not to mention you and me.

Re:Cloud Seeding

[Anonymous Coward]

Please read a bit on "variable confounding" (here you go: http://en.wikipedia.org/wiki/Confounding), especially the part where there ARE ways of isolating variables (i.e. prevent "confounding") even though, yes, the atmosphere and weather are chaotic systems and there is no way to accurately EXACTLY replicate atmospheric conditions.

In science (outside of formal domains, like math), it is often impossible to EXACTLY replicate an experiment or the object of an experiment ("no two living beings are identical", "no two particle collisions are identical", if you use the same definition of "identical" you're using), which doesn't mean there is no way to extract statistical information on physical phenomena. In case you don't remember, we don't do drug trials on clonal populations of humans; we actually test drugs on heterogeneous samples of human populations (protip: read up on "stratified sampling", "design balancing and randomization" and the "law of big numbers").

Re:Cloud Seeding

[mcvos]

I know you think you're very smart. But you really don't understand how different clouds are, or you don't understand what a control group is.

I don't think you understand how little that difference matters if you have some grasp of statistics and use a sufficiently large sample.

If you want your argument to hold water, clouds or planes flying through them would need to be sufficiently rare that you can't get a big enough sample to compensate for the large differences. They might be. I wouldn't know, because I don't know anything about clouds. I do know something about proper experiments with control groups, though.

If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.

If you're honestly unable to distinguish between all those "fish" (which is what you seem to be claiming with respect to clouds), then you don't have much choice applying your results to all "fish". And that's not a problem, as long as you make your test group and your control group big enough that both will have the same ratio of trout, bass, whales and sharks. Then your test results will actually say something meaningful about the effectiveness of your lure, despite the amount of noise in your test.

Re:Cloud Seeding

[rtfa-troll]

If you were going to test a fishing lure, would you use a "control group" consisting of trout, bass, pike, baleen whales, and tiger sharks? Would you then apply the results to all "fish", despite the fact that some of those weren't fish at all? I would hope not.

When you are talking about large scale testing for "fish" you would do it on whatever you call "fish". The trick is, that the control group shouldn't "consist of" anything different from the original group. If you test on "fish" then your control group should be "fish". If you test on "big dark fish" then our control group should be "big dark fish". There are a few important things.

• you start by writing down your procedure clearly and following it.
• you first identify your a target and decide if it is in or out of the experiment
• only after having identified a target, you assign it randomly between the test and control groups.
• you continue the experiment to the end and record the result.

In this case, the group you are targetting is probably "clouds that might potentially be seeded". How you decide that could even be as stupid as "ones fred thinks look good". Because you ask him first and then do the assignment afterwards it doesn't matter. You will see if there is a real effect or not. If there is a real effect, you now repeat the experiment with a bigger group to have better certainty. If there isn't, you may give up and leave it for someone else or you may try to find a different way to select clouds. Again, it doesn't matter what it is as long as you write it down honestly and clearly.

Re:Cloud Seeding

[Anonymous Coward]

But... but... he took a claaaaaaass!

Re:Cloud Seeding

[mcvos]

Unfortunately there is no proof that an external event or condition created the statistical and mathematical variations in the results of the experiment. The conditions can be different clouds, temperature, humidity, and other atmospheric conditions. Academically the clouds and atmospheric conditions have to be and I emphasize have to be identical in the control group to be considered valid. There is no way around it.

They have to be identicasl on average. This is accomplished by making your sample sufficiently big. Don't compare one cloud with seeding to another cloud with a non-seeding plane, compare 100 clouds to 100 clouds. Or thousands, if you have to.

Running a plane is expensive and since it can not be proved then no one will want to fund it.

That is a much better argument. You're saying that running a single experiment is expensive, and running 100 experiments is too expensive for people to fund it, considering the limited interest in the subject. The problems in getting a good control group isn't fundamental to clouds, it's economic.

Re:Cloud Seeding

[nusuth]

Try solving this, you might be enlightened: 2n numbers (not guaranteed to be distinct) are selected by an unknown procedure from 0-100000 interval. You know nothing about the selection process. Therefore you have no a priori information about expected distribution of numbers. You then put those 2n numbers in to 2 collections of n items without seeing the numbers (like "put first 3 numbers in the first collection, next 3 in the second collection etc.".) Someone picks a number m between 0 and n. Then someone else picks one of the sets (this time randomly, say by flipping a coin) and increase m of the numbers by 1, leaving m-n of them as they were. The selection process of numbers to be increased is unknown to you. He might have picked randomly, he might have carefully selected m numbers to increase to lower your chance of success or he might have just increased first m numbers - you just don't know. He then gives you two collections and asks you which one is the collection that had "some of them are increased by 1" function applied. You look for the number 100001, alas, no set has that number. Is there any way you could tell which is which? Can you quantify how sure you are about your answer without knowing m? If you want to be 95% sure of your answer, what should n and n/m be? After you analyse the distribution of numbers in both collections, can you give an upper bound of m with a specified confidence? Does any of this have anything to do with experimentally assessing efficiency of cloud seeding?

Re:Cloud Seeding

[ffreeloader]

You're missing the point. Unless lure A and lure B are exactly the same type of lure, are the same color, etc... fishing them in the same place, the same way can be the entire reason one works and the other doesn't. Even speed of retrieval can affect the action and the results you get. So can the size of the lure. Using too large or too small a lure can affect your results too.

You have to know how the lure was designed to work, how to fish it, the best color for the water conditions and lighting conditions, etc.... Just using the wrong color of lure for the conditions can make all the difference in the world in how many fish you catch. So can water surface conditions. Whether the surface is mirror calm, has a little movement, or even some chop can all affect the performance of two different lures. Quite often it just comes down to local knowledge of what works where and when on that particular body of water.

The number of variables in play in catching fish with lures is incredible. To be a really good fisherman it takes a vast amount of knowledge of fish, how lures are designed to work, where lures are designed to work. etc.... Not catching fish with one lure can also mean that the fish right there have seen that lure enough times that they recognize it and won't hit it. Catch and release fishing has done a lot to educate fish about fishermen and what they use to catch fish.

There's a reason fishing is addictive. It's a very challenging sport, whether you fish to feed yourself or for sport only. You have to adapt to infinitely changing conditions and learn what works when, and why it works when it does work. It also takes a knowledge of where fish will be during which conditions, how active they will be under those conditions. etc.... As I said earlier, the number of variables in play as to whether lure A or lure B works at the time and place you're fishing them are incredibly large in number.

I'll relate one experience I had bass fishing. I'm not much of a bass fisherman, but this day my ignorance of bash fishing worked to my advantage. It was spring time and the bass were holding at the mouth of the creek that fed the lake.

There must have been 20+ guys there fishing and no one was catching anything. I walked up and looked around, looked to see what all I had with me and decided I'd use worms for bait. Well, all the choice spots were taken so I went a little further up the creek where it took a sharp turn and there was a small tree in the water where high water that spring had washed out the dirt supporting it and it had fallen into the creek. I looked at the situation and thought, well, if I was fishing for trout I'd want to fish by allowing my worms to drift in under that tree where the current was pretty strong.

What I didn't know was no one else was fishing it because everyone else knew bass didn't stay in that habitat very often. Plus it was a very difficult spot to fish. It was one of those places in which you catch a lot of stick fish, and lose a lot of tackle, unless you're very careful. To make a long story short I caught 10 bass in less than a half hour.

It was pure blind luck on my part, and the best day I ever had bass fishing. But even though it was pure luck, I had to know where to stand in the current relative to tree, how much weight to use for the amount of current, and just how to drift my bait back under that tree or I still wouldn't have caught anything. I'd learned those skills fishing for trout but on this particular day they worked like a charm on bass. Never had it work again like that either.

There were a bunch of guys fishing worms there that morning. They were fishing the slow moving current using bobbers to suspend their worms up a ways off the bottom. I happened, in my ignorance of bass fishing, to use the correct technique for that day and those conditions. A lot of guys fished the same bait, but only one guy out of the group caught any fish. That's just how finicky fishing can be.

Re:Cloud Seeding

[bunratty]

Yes, I understand what you're saying. It can be difficult to test which lure is better. But it is not impossible. If I and others consistently catch far more fish with lure A than with lure B, we have demonstrated that lure A is better than lure B. If, as you explain, the other variables in the experiment matter so much more than the lures, then in the worst case we would get inconclusive results. In other words, there would be no statistical difference in the number of fish caught by lure A and lure B. I certainly do get your point, but it doesn't mean we cannot do controlled experiments on lures.

Re:Cloud Seeding

[Schadrach]

Always thought that was a Chaos theory thing, where having not infinitely accurate data meant that your model was going to diverge increasingly from reality with time, to the point that the upper and lower error bounds of something like a temperature measurement caused the models to produce drastically different and essentially unrelated predictions within a fairly short period of time, and that was why "about a week" was as far as weather predictions go, with even the latter part of that week getting revised before it rolls around.

Re:Cloud Seeding

[Anonymous Coward]

As a cloud physicist I suggest you need to spend some time with a cloud physics text book not high energy physics textbook before you spout nonsense. You ASSUME (that's the Ass infront of U) that cloud droplets and rain drops are like your particles. They are not. Try your experiments where the source, make up and character of your particles varies not only from experiment to experiment, but minute by minute during the same experiment. The source of the cloud condensation nuclei (CCN) varies as the source of the air parcels changes as the cloud moves. Early experiments showed that sea salt and kaolin clays were acting as CCN's and that the concentration varied both with time and space. The equivalent HEP would be randomly supplying proton, neutrons and electrons in your collisions AND you are not allowed to know which kind of particle or it's energy participated in the collision. Your comment about only caring about the equivalent radar reflectivity shows a basic lack of understanding of physics. The equivalent radar reflectivity (dBZ) is based on an ASSUMED (there's that Ass again) drop-size distribution. There are hundreds of rain-reflectivity relationships that don't work for anything but the cloud sampled.

Re:Cloud Seeding

[bluefoxlucid]

I know you think you're very smart. But you really don't understand how different clouds are, or you don't understand what a control group is.

This is a basic statistics problem.

Consider selecting 300 clouds (out of ALL clouds currently on this planet) completely at random; and then, completely at random, selecting 150 of those. At this point you're thinking, "Some are small, some are big, some are dense, some are..." ... it doesn't matter. We have a random sample of 300 split randomly in half; there's a very, very high chance that each entire set will behave roughly identically. Also, even selecting individual "clouds" of varying sizes, the total volume of each set of clouds should be roughly identical. So should the average density.

You have to understand that cloud behavior is, statistically, very predictable. Every single individual property of a cloud will follow a pattern producing the same graph. This graph is identical to the graph of the number of people who have had so many sex partners (with the X axis being the number of sex partners, and the Y being the number of people who have had that many). For each variable property, there is a specific given unit size where, with the mean at 0 on the X axis, 68% of clouds fall in the range of X values -1 to 1; 95% fall in the range -2 to 2; and 99.7% fall in the range -3 to 3.

So you see, setting up a controlled sample is not hard. Your best bet is to cut a large swath of air space out and split it up into identically-sized pieces; then randomly select your 150 samples (don't split it down the middle). This is more feasible than using the entire world.

Re:Cloud Seeding

[david_thornley]

You seem to think that we have to know a lot about a subject to run an experiment. Actually, we don't. This is fortunate, because otherwise we'd have a great deal of difficulty learning.

We don't know what a given cloud would do, if left alone. We don't know which clouds are really similar to one another in rain-making potential. I assume, from your last paragraph, that we don't know if different parts of the same cloud will react the same way. Given all this, we can't do direct comparisons, but a statistical test is still possible.

Take clouds that look like they might rain. We don't know if they will or not. We have no good way of telling, other than superficially, whether they're even similar. Heck, dolphins look a bit like sharks. Randomly divide the clouds into control and experimental groups as they come up. That way, we have groups with about the same distribution of mystery variables, by the law of large numbers. They will still vary by an unknown amount, but we can get the distributions to be more similar by simply choosing more clouds.

Now, we define a criterion for "rain", probably based on a rain gauge in a specific spot, or perhaps gauges in multiple spots. We keep track of the percent of rain vs. no rain for the groups. There will be different results, of course, so we use some simple statistics to see if the differences are significant.

Suppose we find a statistically different difference between two groups, say that seeding causes more rain than leaving clouds alone. We don't know why. We don't know which clouds it'll work on. We don't know how it works on specific types, because we can't tell which specific type: seeding may increase the probability of rain in one type of cloud, and decrease it in another, and we may not be able to tell one type from the other. We don't even know if this experiment will necessarily hold in another place with different clouds. Nevertheless, we have a conclusion. We can run more tests under different conditions and eventually arrive at a series of observations that may say that cloud seeding generally works X percent of the time.

We still don't have a theory, since we have no model of clouds that says why it works, but we have some criteria that any theory must satisfy.

(I'm exaggerating here, of course: people tried seeding because a basic understanding of clouds and rain indicated that it might work. We can tell various different things about clouds other than "looks like rain" and "doesn't look like rain". However, this shows we don't need to understand something to experiment with it.)

Re:Cloud Seeding

[Anonymous Coward]

So conspiracy nut Alex Jones was right after all. The high-flying planes are changing our weather.

Except if the article is right, it's all unintentional and accidental and therefore unlike the intentional government plot Alex Jones railed on about.

Re:Cloud Seeding

[Locklin]

The issue seems to be that either apoc.famine doesn't understand statistics or that the variance of the population is too large. If the effect of seeding is small, and the population variance of clouds is very large, it may require very large sample sizes to test for significance between randomly sampled groups. Remember, each sample requires flying an airliner, so large sample sizes may be prohibitive.

Re:Cloud Seeding

[Locklin]

That works great unless you have a small effect size, large population variance, and large samples are prohibitive, perhaps because they require flying airliners...

Re:Cloud Seeding

[vrmlguy]

I would think anyone who understands how to design experiments would see the need for a proper control group.

We've already seen that no one who understands how to design experiments has anything to do with the study of weather or climate.

Actually, just the study of weather, I haven't seen any climatologists chiming in yet.

BTW, I suspect that you're making a veiled criticism of climate change predictions. If so, then you're taking aim at your allies: researchers at George Mason University and the University of Texas at Austin found that only about half of the 571 television weathercasters surveyed believed that global warming was occurring and fewer than a third believed that climate change was “caused mostly by human activities.” http://www.nytimes.com/2010/03/30/science/earth/30warming.html

Re:Cloud Seeding

[IndustrialComplex]

Please, provide a citation stating that it's impossible to perform controlled experiments on clouds, preferably with a lucid explanation for why it is so.

I'll give you a slightly tongue in cheek response. But it does identify some problems.

It's just too damned expensive to fly planes through several thousand clouds in a single study. The cost of making a proper control group would be meteorological.

Re:Cloud Seeding

[ffreeloader]

Yes, you can do controlled experiments, but you have to do them in a controlled environment. Lure manufacturers have large tanks in which they test their lures during development. They control ph, temperature, water "color", water clarity, lighting, etc... to make sure they have repeatable results. In addition they test lure color, size, retrieval method, retrieval speed, etc... under each condition and film the entire procedure under water. What they do is a far cry from real world fishing, but it is logical and repeatable and thus leads to solid conclusions as to lure efficacy.

Going from one fishing site to the next can change all the water variables and lighting variables, as well as what the fish are used to seeing and what they feed on, as well as fishing pressure and what lures are most used where, so how are you going to know what to factor into your decision on the rating of lures? All you're proposing, in reality, is doing what fishermen do every day of the year all around the world: testing by trial and error to see what works that day until you know the water and the fish. It's hardly scientific experimentation. It's just real world fishing.

There are fishing pros who measure ph, clarity, temperature, whether the water is rising or falling, factor in the phase of the moon (seriously), when the last storm occurred, and the size of fish they want to catch in choosing the size, color, and type of lure they are going to use. They fish scientifically, not with the random method you propose for testing lures. What you're proposing is equivalent to the level of skill that a noob fisherman uses when he first starts fishing. You're, in fact, proposing what amounts to shooting in the dark as a scientific method.

I'd imagine that clouds are far more complex than fishing, and that conditions within a single cloud can vary much more wildly than the water and lighting variables at play in fishing. Plus, they can't be modeled in a controlled environment as the fishing variables are.

Re:Cloud Seeding

[clone53421]

Nonetheless, if you randomly assign 100 clouds to one group and the other 100 to another group, then add up the precipitation totals of the two groups, the totals should be approximately equal.

I think his whole point is that there is so much variability from one cloud to any other cloud that your statement is basically worthless because 100 clouds is nowhere near a large enough number to make an assumption on how much rain they’ll produce. It might take tens of thousands, millions even, in order to safely assume that the variability had been eliminated... and you might have to take them from widely different climates and altitudes or you’d never get an accurate prediction.

For instance, here is a chart showing the annual precipitation measured in various locations throughout Arizona. Now I have no idea how that even relates to the number of clouds actually passing over the rain gauge, per year; that number might also vary wildly from one year to the next. Take the annual rainfall, divided by the number of clouds that generated it... that will also vary wildly year-to-year. In other words, you could probably sample clouds for a whole year and still not have counted enough clouds for your rainfall prediction to be as accurate as you’d need it to be.

Re:Cloud Seeding

[The_Wilschon]

So, ignoring your spurious insults for the moment, what you are taking issue with is my proposed method of measuring approximate total rainfall? That's fine. I am perfectly willing to take any measurement of approximate rainfall, even if it is quite crude (and then you account for such crudeness as systematic errors). Once you've got such a measurement, none of the rest of what I said has anything to do with cloud physics. It's all statistics and experimental design. You still just need to populate two one-dimensional histograms and attempt to observe a difference in distribution between the two. All the enormous variability in clouds is subsumed in the notion that we are sampling from the distribution of all clouds (or all clouds over Norman, OK during the month of June, or whatever). The only thing you have to worry about is getting enough samples to populate your histograms, like I said.

Yes, cloud physics is hard, and no, I did not mean to imply that it was not. But it is not so hard as to render such an experiment impossible.

Re:Cloud Seeding

[The_Wilschon]

Yeah. Your experimental sensitivity would almost certainly be total crap because your error bars would be too large and you couldn't get a large enough sample. But you could still design and run the experiment. My point was about the triviality of the experimental design in this case.

Re:Cloud Seeding

[Anonymous Coward]

Put simply, leatherwork is a human technology built on demand - the universe didn't invent it.

But humans are the result of natural processes in the universe, and if you wish, the leather shoes they create are also the result of a long history of transitions between thermodynamic states. So on one hand you are offended by some statement I made that you claim smells faintly of creationism (I'm sorry, but I really don't know how you came to this conclusion), and in the statement above you seem to claim that the universe had no part in the creation of leather shoes. So what are humans? Supernatural? Not part of the universe? Whether something is created directly by humans (leather shoes), or without human interaction (clouds), does not preclude humans from doing experiments on them. You say my analogy fails because I use a simple example of an experimental design that blocks for some variables, and then use the same idea to block for many more variables in the case of clouds, and I don't know how you come to this conclusion. It's not even an analogy at all. In both cases I'm using the process of experimental design and the scientific method. Do I want to spin this into a global climate change argument? I had no intention of doing so, and (again) I don't know how you are produce this conclusion. There is no bait, except perhaps with this post. You work for a living? That's all nice, congratulations, you're just like most people. I don't expect a response because you "don't give much of a fuck anymore", and that's fine by me, because I'm sure I cannot even begin to imagine the conclusions you'll make from this post. Creationism, global climate change, teleological descriptions of the universe, dystopias, are all related by the fact that none of them are at all related to any of the posts in this thread. And that statement of yours that I quoted implies you place humans above other natural processes. Better work on some yoga, so that you can kick your own ass.

Re:Cloud Seeding

[Anonymous Coward]

Arguing that a cloud experiment can't be done because of the complexities involved is quite silly, and here's an example of the argument applied to a more mundane experimental situation. I want to test the strength of metal bars made of different material. I doubt anyone in this thread would say that this experiment can't be done. But here comes a naysayer, pointing out that "you can't possibly know all of the crystallization structures in the metals. You can't possibly account for the type and distribution of impurities. There's is no way to calculate the distribution of electric charge in the rods, because they each involve 10^24 charged particles, and they once took a class in electro-magnetics, and know for a fact the it is too complicated to calculate. You just don't understand the complexities involved, and the experiment cannot be done. Each metal bar is at the microscopic level, very different, and you can't possibly account for all of the variables."

See? If the metal rod example is too mundane to draw a connection, substitute wood boards (e.g. testing cedar vs. oak), and if that's still too mundane, substitute experiments involving human physiology, and if that's too mundane... I hope you get the picture. And the HEP guy knows what he is talking about, so the accusations that he is spouting nonsense is quite misplaced. Perhaps radar reflectivity isn't the best way to measure precipitation, but that's where you come it. Give us a better method. The end result is that the experiment can be done. If the effect is small, then we'll just have to accept the null hypothesis when we're done. If the effect is large, then we'll reject it, and know that we have good statistical evidence that cloud seeding increases / decreases precipitation, with our confidence related to p-values, power, and more statistical yada yada.

Re:Cloud Seeding

[Anonymous Coward]

If the effect is small, then we have gained information after the experiment. Knowing that cloud seeding doesn't work (or works only slightly) is every bit as important as knowing that it does work. Either way, the experiment is a success.

Re:Cloud Seeding

[shadowbearer]

  Since you seem to be all scientific-like, you might want to learn the basics of language structure, paragraphs, etc. I can parse what you wrote but it takes more effort than it's worth to try and reply to.

  I don't care if you are a hundred years old, learn how to use the language properly. You don't have the excuse that english isn't your first language.

  Your analogies are getting further away from the subject the more you post, as is your understanding of what life is about.

Creationism, global climate change, teleological descriptions of the universe, dystopias, are all related by the fact that none of them are at all related to any of the posts in this thread.

  Just so.

SB

Re:Cloud Seeding

[Anonymous Coward]

And the personal attacks just keep on coming. English is my first language, I'm sorry my last posts format didn't please you. (You're probably upset about something that is amiss with the last sentence.... I feel your pain.)

I really like how you say I'm the one wandering, when it is your posts that bring up all of these wonderful unrelated topics. "Understanding what life is about" plus all of the stuff about language structure. Deliciously ironic. You're trying way to hard to make a point. Thanks for arguing with an anonymous coward, seriously, I appreciate it. May peace be with you:)

Re:Cloud Seeding

[Anonymous Coward]

Put simply, leatherwork is a human technology built on demand - the universe didn't invent it.

But humans are the result of natural processes in the universe, and if you wish, the leather shoes they create are also the result of a long history of transitions between thermodynamic states. So on one hand you are offended by some statement I made that you claim smells faintly of creationism (I'm sorry, but I really don't know how you came to this conclusion), and in the statement above you seem to claim that the universe had no part in the creation of leather shoes. So what are humans? Supernatural? Not part of the universe?

Whether something is created directly by humans (leather shoes), or without human interaction (clouds), does not preclude humans from doing experiments on them.

You say my analogy fails because I use a simple example of an experimental design that blocks for some variables, and then use the same idea to block for many more variables in the case of clouds, and I don't know how you come to this conclusion. It's not even an analogy at all. In both cases I'm using the process of experimental design and the scientific method.

Do I want to spin this into a global climate change argument? I had no intention of doing so, and (again) I don't know how you are produce this conclusion.

Creationism, global climate change, teleological descriptions of the universe, dystopias, are all related by the fact that none of them are at all related to any of the posts in this thread. And that statement of yours that I quoted implies you place humans above other natural processes.

I tried to format it better for you. I even took out the stuff that I found entertaining when making the original post. Regards.

Re:Cloud Seeding

[bunratty]

Yes, you can do controlled experiments, but you have to do them in a controlled environment.

No, you do not need a controlled environment. All you need to be able to do is to alter the independent variable and measure the dependent variable. The sampling method makes sure that the differences from the individual trials cancels out by making the probability distribution of the control group and the experimental group close to each other. If you measure a significant difference in the dependent variable between the two groups, you've demonstrated the likelihood of a causal relationship between the indpendent and dependent variable. Try reading the other posts for details explanations of why this is true. Or read any description of the scientific method.

Re:Cloud Seeding

[bunratty]

Yes, that is a valid point. But that doesn't mean you can't find a control group for clouds, which is what his assertion is. Finding a control group for clouds is exactly the same as in every other experiment -- random assignment.

Re:Cloud Seeding

[bunratty]

Yes, that is a valid problem. It would be expensive to perform controlled experiments on clouds. But not impossible.

Re:Cloud Seeding

[clone53421]

Yes, but it’s impossible to get an appropriate sample size because a halfway-decent representative sample would be prohibitively large and expensive to take.

Re:Cloud Seeding

[bunratty]

If you were willing to spend the money, you could do it. Therefore, it is possible.

Re:Cloud Seeding

[clone53421]

Right, if you’re willing to spend the entire operating cost of the US airline industry for a few years you might be able to get something that came close to a representative data sample. Maybe.

cue the contrails conspiracy

[ducomputergeek]

in 3.....2......1

denied.

[conspirator57]

epic fail

Chemtrails?

[courteaudotbiz]

How long before a conspirationnist comes up with a chemtrail comment?

Re:Chemtrails?

[JWSmythe]

    Come on, those guys are entertaining. :) I love the pictures where they show intersecting lines and say that the planes have been flying patterns to drop evil chemicals on the population. Well, the evil chemicals are present, but that's the aircraft's exhaust.

    And for those who don't know, the "grids" are usually created by flights departing in two different directions. They get a pretty regular grid pattern because at busy airports, flights leave at a fairly regular interval. If you read up on how aircraft work, you'll see that the FAA requires a period between large aircraft due to the disturbed air. Failing to do so, the disturbed air would likely do "bad things" (i.e., unintended intersection of the flight path and the ground, in most ungraceful ways).

    Err, I mean every aircraft is fitted with mind altering drugs that is distributed over the city, so some secret government agency can observe how the population reacts. Myself, it makes me laugh at conspiracy nuts who don't really know what they're talking about. I guess the mind control is working. :)

Re:Chemtrails?

[bunratty]

So, you admit the planes are disturbing the air and doing bad things. That is disturbing, indeed!

Re:Chemtrails?

[__aasqbs9791]

He is obviously a plant by the Warren commission to distribute falsehoods among the masses. But what even he doesn't know is who is actually behind the commission. My research shows the Girls Scouts of America are in league with the Greys on that one.

Re:Chemtrails?

[JWSmythe]

Well, the bad things would be something like if a Cessna tried to take off immediately behind a heavy jet, the Cessna may find himself tumbling down the runway in most ungraceful ways. It's not limited to small vs big aircraft though. A heavy aircraft following another can have unintended (and nasty) results.

Re:Chemtrails?

[Falconhell]

A good photo of what an aircraft does do to the air see;

http://www.skysoaring.com/albums/gliderhumor/Box_This_Wake.jpg

Re:Chemtrails?

[bunratty]

Then it could cause a plane to crash, just like terrorists cause planes to crash? I see.

Re:Chemtrails?

[clarkkent09]

Never heard of chemtrails before but I did notice that my cat is shedding more fur in the summer than in the winter, and there are also more flights from the local airport in the summer. If they can cause cats to shed, imagine what they are doing to your brain! Thanks for opening my eyes.

Re:Chemtrails?

[PhreakOfTime]

I got sucked into a similar discussion once. I will never make that mistake again.

After doing some back of the envelope calculations, using the average size of cloud droplets, the velocity those droplets fall, and the average height those clouds are... I pointed out that the clouds seen over your head would take up to 10 hours(or substantially longer) to fall to ground, and even with a small breeze, would end up hundreds of miles away from the location seen by the time they would reach the ground.

Even faced with that simple math, they would STILL insist that they could see the 'residue' falling into their yard from the airplanes above....

Re:Chemtrails?

[JWSmythe]

    WOW! That's an amazing shot. All the shots I'd seen before were near the ground, to show how the wake turbulence is at ground level, like this one.

Re:Chemtrails?

[JWSmythe]

Oh, I see your point now. It's a tool used by terrorists. Anyone causing wake turbulence would therefore be a terrorist. Just like all those evil people caught possessing DHMO.

Re:Chemtrails?

[petermgreen]

unintended intersection of the flight path and the ground, in most ungraceful ways
LOL

Kinda similar to a story I heard from my phd supervisor (dunno if it's true or not and my memory of the exact term may be hazy) that someone told him not to use the "M word" and instead to call the things they were talking about single use unmanned air vehicles (i'll leave the reader to figure out what the "M word" was).

Re:Chemtrails?

[bunratty]

It's a fact that nearly all felons consumed significant quantities of DHMO in the hours before committing their crimes. And nearly all heroin users smoked marijuana before turning to harder drugs.

Re:Chemtrails?

[zippthorne]

Meh oversight on DHMO is too stifling. People in industry tend to use a lot more of the relatively unregulated hydric acid, instead. It's a very good solvent: it dissolves almost everything.

Re:Chemtrails?

[bunratty]

I'm just wondering what the heck is in our water supply!

Re:Chemtrails?

[Anonymous Coward]

right now. I don't like the way it's all going but on the + I'm partially exceited by all u little rat wieners who're gonna get a shock

when the wolves are at your door and you've no powere for your iphone nano. You'll have to worry about things like fresh water, and self defense.
Bye wieners!

Re:Chemtrails?

[nido]

I live in Phoenix and I pay attention to the skies. Haven't seen a chemtrail in a couple months. Maybe it's the summer heat (moved here in November, have seen the chemtrails elsewhere in Arizona before), maybe they stopped spraying when BP's oil volcano went off in the gulf. I don't keep logs or take pictures, so this is just from memory.

With that said, there are still planes flying in and out of Phoenix Sky Harbor International. I'm in one of the flightpaths, so I see those planes all the time. The planes that are approaching and leaving Sky Harbor never leave chemtrails. Perhaps the chemtail planes are drones...

Myself, it makes me laugh at conspiracy nuts who don't really know what they're talking about.

Maybe you live where it's cloudy most the time. If you've never seen an actual chemtrail, it's understandable to assume that they don't really exist. Arizona Skywatch has some pictures. But the site is not worthy of your visit - just something else for you to scoff at.

I guess the mind control is working. :)

We agree here. :)

Re:Chemtrails?

[JWSmythe]

    I don't know about the 10 hours or 100 miles, but I didn't do the math. :) I live in Florida, so frequently watch the weather formations on TV (and now the Internet), so I'm very aware of cloud movements. We get some pretty nasty storms here in the summer (think instant hurricane type weather), so it's advantageous for us to know what's happening around us. Usually we can see bands of rain forming miles off the coast, and time our activities accordingly. If I have to go for a long drive, sometimes it's a race against the weather. More than a few times, I've been caught in it, and had to stop because I couldn't see more than a few feet in front of my car. When that breaks, you see the line of cars that pulled over because they couldn't see either.

    The only "residue" falling from an aircraft that I could imagine that they could see falling into their yards immediately under the flight path would be if a part fell off the plane. That should be pretty obvious. "Look honey, there's a jet engine in the front yard." :)

Re:Chemtrails?

[JWSmythe]

    My god, I didn't realize how bad the epidemic had grown! Outlaw it now!

Re:Chemtrails?

[JWSmythe]

    Contrails are very dependent on the humidity in the air. Military or commercial pilots can correct me if I'm wrong. In really dry air, you won't see them at all. If there's enough humidity, they'll make pretty trails. Even if you don't have the humidity at ground level, higher layers of the atmosphere can have significantly different characteristics.

    The picture in the link looks like a very nice standard rate turn. It's probably a departure, heading towards the destination city. Just before the turn, you can see where there was a little less humidity at that altitude during his climb, so the contrail was thinner.

    Contrails don't usually happen close to the ground. It's very similar to the action of cloud formation, with a bit of encouragement by the pressure differences created by the wing. Clouds at ground level (fog) are relatively rare to clouds at altitude. You wouldn't normally see any close to arrival or departure, since the aircraft are pretty low. Even in nice subtropical Florida, where I used to live on the approach of a major airport, and now drive by two busy airports on a regular basis, I can't see that I've ever seen a contrail when they were low.

    BTW, current humidity here, 78%. Current humidity for Phoenix, 12%.

Re:Chemtrails?

[JWSmythe]

    hehe, that's a good way to say it. Those sometimes of have an intended intersection with the ground though, in most decorative ways.

 

Re:Chemtrails?

[Falconhell]

A couple of vids showing wing vortex well;

http://www.youtube.com/watch?v=E1ESmvyAmOs

http://www.youtube.com/watch?v=uy0hgG2pkUs&feature=related

Re:Chemtrails?

[nido]

After posting I remembered a relevant anecdote...

I used to live in the mountains, ~80 miles from Phoenix. On this particular day I looked up and noticed multiple jets in the sky, which were presumably headed to/from Los Angeles. All were at cruising altitudes. Some jets were laying contrails that rapidly dispersed and disappeared, while other contrails "hung around" and dispersed like chemtrail proponents said.

I guess the main thing is "who do you trust"? I figure this wouldn't be the first classified program ever to be undertaken...

P.S. Phoenix's humidity is very low for most the year. It spikes when it rains, then goes back down. According to this chart, average afternoon humidity only varies by 21% throughout the entire year.

Re:Chemtrails?

[JWSmythe]

    A lot of that has to do with the specific weather conditions where that contrail was. Sometimes it'll disperse quickly. Sometimes it'll take some time. Humidity, wind, temperature, pressure, aircraft configuration and load all change the way it works. You can have significant differences in a relatively small area.

    I seriously doubt any commercial carrier has equipped their aircraft with any super secret government gassing project. :) How exactly do you explain to the ground crew, "ok, fuel it up here, and then fill with this hose marked classified US Gov't property here." Someone besides the conspiracy nuts is going to talk.

Re:Chemtrails?

[nido]

I seriously doubt any commercial carrier has equipped their aircraft with any super secret government gassing project.

When I read the links years ago, they said that the doping agents go straight into the jet fuel, and pass through the turbofan without causing other problems.

Here's a search that might turn up something appropriate:
http://www.google.com/search?q=patent+aluminum+jet+engine+chemtrail

Re:Chemtrails?

[BoogieChile]

So this pouring rain isn't from the storm cell that formed up about an hour ago, it's from a completely different cloud that passed overhead just after breakfast? I think your precipitation model needs some work.

Re:Chemtrails?

[JWSmythe]

    Their implication is that there would be a white plume from the engines. If it were mixed with the jet fuel, it would always be present. Folks would notice if aircraft were putting off that kind of smoke. It may not be totally noticeable when taxiing, but it would be obvious during takeoff.

    Being that aircraft all fuel from the same source at the airport, there would be no difference between aircraft, that is usually reported with chemtrails. As I've read it over the years, some dissipate quickly. Some linger for a long time. If it was included as a fuel additive for commercial aircraft, there would be no "sometimes" to it.

    And just because a patent was issued doesn't mean that it really works, or that it's in use. People get patents all the time that lay dormant forever.

Re:Chemtrails?

[PhreakOfTime]

I was talking about a conversation I had with someone who held the belief that 'contrails' were chemical experiments being performed.

Condensation trails, in otherwise clear skies, do not 'fall as pouring rain'. At no time did I mention there was a storm of any kind. Condensation droplets generally have a smaller diameter, by a factor of many magnitudes, than precipitating raindrops. A typical cloud droplet is on the order of 0.02 mm, and falls at a rate of 0.02 mph. The clouds are generally at flight altitude, which can be assumed to be between 25,000 and 35,000 ft(~4-6miles). The calculations were performed with the smaller droplets just as stated, as that was what the discussion was about.

I think your reading comprehension model needs some work.

Re:Chemtrails?

[Anonymous Coward]

How long before a conspirationnist comes up with a chemtrail comment?

How long before a Slashdotter proposes limiting all aircraft to warp factor 5?

Re:Chemtrails?

[Anonymous Coward]

If you cared about brain damage you wouldn't keep a cat. Seriously.

Surprised?

[confused one]

So, we're surprised when a large metal object that sucks in cold air and spits out water vapor (and CO2) by the ton, affects cloud formation?

Re:Surprised?

[apoc.famine]

Not many people studying clouds are surprised. It's pretty well established that any sort of disturbance can affect cloud formation. There have been discussions for years that "cloud seeding" may just be caused by the plane flying through the clouds.

Not surprising

[JWSmythe]

    This isn't terribly surprising. Clouds are a delicate formation of moisture that hasn't collected into dense enough masses to fall. Aircraft disturb the air, blowing that moisture around. We've known about contrails for an awful long time. I wouldn't be terribly surprised to find that particles in the exhaust give the moisture something to cling to (i.e., cloud seeding).

    Those are some nice pictures though.

Re:Not surprising

[Anonymous Coward]

As the Air is accelerated over the wing it condenses the moisture within it, thus precipitating percipitation. If the conditions are right - it canresult in a chain reaction of sorts. The mystery is why anyone thinks this is a mystery! Any pilot who has flown through clouds can tell you this.

Re:Not surprising

[Anonymous Coward]

I've previously read a write-up on persistent cloud formations over shipping lanes and harbors so the exhaust itself is likely a factor.

Can't find anything in depth at the moment, but there is mention of it here

Re:Not surprising

[JWSmythe]

    You don't have to be a pilot to observe it. I've seen some very nice examples of contrails, while riding in commercial aircraft. I like to sit behind the wing, so I can observe what the pilot is doing. It's not like I can do anything about it, but at least it's better than sitting back completely oblivious to what's happening. A few drinks later, it doesn't really matter though, I'll take a nice nap until I hear the landing gear go down. :)

Re:Not surprising

[JWSmythe]

    Hmmm, that's interesting. I hadn't seen anything about it before, but I found several references for more information. Thanks, now I have some reading for today. :)

Re:Not surprising

[JWSmythe]

Here's a couple writeups from NASA on the phenomenon, with some interesting pictures.

    Of course, since it's from the government, conspiracy nuts will say it's disinformation. :)

 

Re:Not surprising

[zippthorne]

    A few drinks later, it doesn't really matter though, I'll take a nice nap until I hear the landing gear go down. :)

Based on what I've seen of pilots, they're thinking the same thing....

More of a duh, really.

[vandoravp]

They are just giant butterflies, after all.

Re:More of a duh, really.

[dameron]

And I dreamed I saw the bomber death planes
Riding shotgun in the sky
Turning into butterflies
Above our nation

-JM, Woodstock

Just sorta comes to mind.

Re:More of a duh, really.

[mcgrew]

Butterflies flutter by, birds and airplanes don't.

I thought this was well established?

[Deagol]

The data from the near-universal grounding of US airspace the days following the 9/11/01 attacks shows pretty conclusively that air traffic has a non-trivial affect on weather patterns. Or at least that's what's I recall from the time.

Re:I thought this was well established?

[Dragoniz3r]

One instance != "well established"

Re:I thought this was well established?

[cowscows]

That's not always true. While one instance certainly isn't enough data to completely explore and explain a phenomena, it can certainly establish that said phenomena exists.

And it's not like we're talking about a data-set of one plane canceling a flight. We're talking about a couple of days, and tens of thousands of flights, all across a big stretch of the planet. That's more than just an anecdote.

Re:I thought this was well established?

[Anonymous Coward]

Happened again with the Icelandic volcano. Thats two data points.

Re:I thought this was well established?

[LoudMusic]

Certainly. But that second data point is clouded with mud and ash.

Re:I thought this was well established?

[lawpoop]

PBS had a great show called Dimming the Sun and IIRC they delve into showing how the 9/11 air traffic halt raised the temperature in American cities by 1 or 2 degrees. The contrail cover from planes reflect more light from the sun.

Re:I thought this was well established?

[Abcd1234]

PBS had a great show called Dimming the Sun and IIRC they delve into showing how the 9/11 air traffic halt raised the temperature in American cities by 1 or 2 degrees.

Err, no, that's not right.

What they found was that the night-day temperature difference increased by about a degree, which makes sense if contrails are insulating the atmosphere (due to less heat escaping at night).

Re:I thought this was well established?

[mavasplode]

Isn't it obvious? The aircraft were keeping the sky clean. Ground the aircraft and look what happens.

I don't see

[Anonymous Coward]

what's the problem {?|.}

Tenerife

[bigtomrodney]

It is well known locally on the Canary Islands that this happens. Almost all flights come in on Tuesdays and Saturdays if I remember correctly - they're almost all package deals and charters. By the afternoon on those two days the temperature drops several degrees celsius and you'll see clouds. I even saw a dribble of rain once.

I was a complete skeptic when I was told this as I arrived, but like clockwork on those days I always saw the same thing. The crazy thing is that any other day of the week around the summer you can expect mid-to-high thirties and rarely a cloud in the sky. So maybe not scientific, but anecdotal evidence anyway.

Re:Tenerife

[bazorg]

any change when the whole european airspace was closed a while ago?

Re:Tenerife

[Anonymous Coward]

You mean when it was closed because of a volcanic ash cloud? I'm sure we can attribute any and all weather changes entirely to the lack of airplanes...

Re:Tenerife

[bigtomrodney]

It's funny you ask that, we had a few days of sunshine here in Dublin when our airspace was closed and that was the first thing that was suggested. I mean, it's Ireland...sunshine is on backorder here.

Unintended Consequences

[Anonymous Coward]

Sure they weren't just emptying the onboard toilets?

Re:Unintended Consequences

[AnonymousClown]

Sure they weren't just emptying the onboard toilets?

Then there would have been blue clouds and blue snow.

Anyway, Pilots couldn't even if they wanted to.

seen following 9/11

[cetan]

Are these studies the follow-ups mentioned here?

http://archives.cnn.com/2002/TECH/science/08/07/contrails.climate/index.html

lolwut?

[Loopy]

Changing the airflow and/or temperature in parts of cloud formations causes changes in the precipitation of said clouds? Say it ain't so!

Military Applications

[somaTh]

Am I the only one that considered flying in mass numbers over areas that have the right conditions to flash flood it? Or in the path between a country's fields and their normal cloud movements to cause a drought? Maybe I'm assuming precision that isn't there.

I guess it could be used to bring rain to fields. That could be good, too.

Re: Military Applications

[Black Parrot]

Am I the only one that considered flying in mass numbers over areas that have the right conditions to flash flood it?

Only as in "dambusters".

Potential AGW support?

[OzPeter]

I'm not deep into the AGW/anti-AGW arguments (and not trying to start a flame war), but I thought that one of the anti-AGW arguments was that in general humans can't affect climate. This sort of research would seem to suggest that humans can affect climate and hence nullify some of the anti-AGW stance - or are these effects so localized that you can only state that the humans are affecting weather and not climate?

Re:Potential AGW support?

[Anonymous Coward]

According to the article the effects are very localized, so it's only weather, not climate.

Re:Potential AGW support?

[Anonymous Coward]

Unless hundreds of thousands of aircraft are going around causing these "localized effects", 24 hours a day, seven days a week. (Hint: that's the scope of the air transit industry)

Re:Potential AGW support?

[Anonymous Coward]

Change enough of the weather, you're going to change the climate.

It's like the Dust Bowl. They didn't just ruin one farm.

Re:Potential AGW support?

[Charliemopps]

Affecting the local climate is one thing, affecting it globally is entirely different.

Re:Potential AGW support?

[lawpoop]

I thought that one of the anti-AGW arguments was that in general humans can't affect climate

. If a person believes this from the outset, they have an ideology ( "Man can never fly as birds can" "No thing can travel faster than the speed of sound" "Man can never affect the climate" ), and probably no amount of evidence will dislodge them from their position.

If they believe that humans haven't affected climate, then there's hope :)

Re:Potential AGW support?

[Anonymous Coward]

I was expecting some trolling saying the opposite, actually, say some tosh along the lines of "see, there's the *real* cause of global warming. Greenhouse gases hah, it's all just planes: now excuse me while I stick my head back in the sand".

Re:Potential AGW support?

[Graff]

I'm not deep into the AGW/anti-AGW arguments (and not trying to start a flame war), but I thought that one of the anti-AGW arguments was that in general humans can't affect climate.

First off, there are morons on both sides. Some people loudly exclaim that humans have ruined everything and some roar that humans have no effect on their environment. Both points of view are ridiculous.

The more reasonable proponents of climate change assert that mankind has had a measurable, long-term effect on the environment that will be difficult to reverse and requires drastic and immediate measures to prevent a catastrophe. Opponents of this point of view argue that the environment has gone through many similar changes in the past and that there is no clear evidence that mankind is the cause of current short-term trends that have been observed.

Of course mankind can affect climate on a local, short-term scale, that's been established and shown many times. The question is whether or not there are any large-scale, long-term, potentially difficult to reverse or control changes. It's a tough question to answer because we really don't have a great understanding of this extremely complex system known as Earth. The fact that aircraft can effect cloud formations has been known for some time and new data is a good thing but it doesn't really give either side much real evidence either way.

Re:Potential AGW support?

[Anonymous Coward]

So if a plane affects the local climate, and we've got plane all over the globe...

Oh, no, you're totally right! We get local climate change, just spread out all over the globe.

Jesus, all those fucking scientists and liberals are MORONS!

Re:Potential AGW support?

[gillbates]

We've known for a long time that humans can affect not only weather, but climate. Since the 60's, we've known that clouds seeded with silver nitrate will produce precipitation. IIRC, the same was demonstrated with chips of solid carbon dioxide. However, that said -

We still do not have enough evidence to prove that burning fossil fuels will produce global warming. Now before I continue, let me just get this out of the way: there is a difference between someone who believes global warming *can't* be true in the religious sense, and someone who recognizes that climate is a difficult subject for which we just don't have the answers now. There will always be anti-AGW folks around regardless of where the science goes and what happens to the climate. That said, the AGW theories have these difficulties:

1. The first is political: the fallout from the IPCC scandal is going to take years before the public will believe them again. But it hardly matters because,
2. Global temperatures have been on the decline for the last decade, much as they did during the turn of the century 100 years ago.
3. We can probably agree that CO2 is a greenhouse gas; what we can't explain is why increased generation of CO2 hasn't resulted in a proportionate increase in the atmospheric CO2 levels. Some say it is being absorbed by the oceans (possibly correct) and will acidify them. (Also possibly true, however, a great deal of CO2 will be necessary to sufficiently alter the pH enough to matter.)

At this point, we simply don't have the scientific certainty to claim AGW is happening, and that it will be catastrophic. Even were we to accept the AGW theories at face value, they are so filled with qualifying factors that we could not conclude that we are in imminent danger. We could say that change is going to come, but we can't quantify the impact. Given the timescales on which climate changes, it would hardly be an unmitigated disaster on a global level. Even if the direst of predictions proved true, we'd have more than ample time to adapt. (Keep in mind the US sustained not one, but two wars in the Middle East, at the cost of trillions of dollars. Imagine what the same could do to relocate US cities inland, if necessary.)

The simple fact of the matter is, though, that we're well past peak oil, and AGW or not, we're going to stop burning it someday. So it only makes sense to buy into renewable energy technologies while they're cheap than wait for the oil to run out and be put over a barrel (no pun intended) by the solar power companies. If you want people to stop burning fossil fuels, you just have to give them a cheaper alternative. You don't have to lie to them about global warming.

Re:Potential AGW support?

[Rakshasa Taisab]

We still do not have enough evidence to prove that burning fossil fuels will produce global warming.

It's well established scientifically that burning fossil fuels, and the injection of CO2 into the atmosphere, causes temperatures to increase. It's pretty basic science that can be replicated in laboratories. What you perhaps meant was that we only have estimates for how much CO2 is needed for e.g. 1 degree of warming?

The first is political: the fallout from the IPCC scandal is going to take years before the public will believe them again.

We also have people who think intelligent design is good science.

Global temperatures have been on the decline for the last decade, much as they did during the turn of the century 100 years ago.

I solved the global financial meltdown by flipping the charts upside-down.

We can probably agree that CO2 is a greenhouse gas; what we can't explain is why increased generation of CO2 hasn't resulted in a proportionate increase in the atmospheric CO2 levels. Some say it is being absorbed by the oceans (possibly correct) and will acidify them. (Also possibly true, however, a great deal of CO2 will be necessary to sufficiently alter the pH enough to matter.)

So the large global study that found half the missing CO2 released since 1800's having been absorbed by the oceans, dropping PH and conclusion that a third of the ocean's capacity to absorb CO2 has been used was... Bunk?

Even were we to accept the AGW theories at face value, they are so filled with qualifying factors that we could not conclude that we are in imminent danger. We could say that change is going to come, but we can't quantify the impact. Given the timescales on which climate changes, it would hardly be an unmitigated disaster on a global level.

The quantification you're looking for was done in the IPCC report. Since you're a super-climatologist that obviously know better than those attention-hungry idiots, why don't you make your own report?

And those qualifying factors you talk about? Let me just say that if I wanted to fly, I'd never get on board a plane designed by one of those anti-AGW proponent. Even if it cost a quarter of the price.

It's not that I'm taking some kind of moral high ground or anything, I just don't think I'll be able to roll a yatzhee trice in a row every time I fly.

Re:Potential AGW support?

[noidentity]

I think the planes are just hastening the inevitable, rather than causing something that wouldn't have happened, so the average isn't affected, just the instantaneous.

Re:Potential AGW support?

[Anonymous Coward]

Sounds like you don't know the difference between climate and weather. Hint, you measure climate from now to a time before planes existed.

Re:Potential AGW support?

[Anonymous Coward]

... and you'll find that the increase in global flights correlate perfectly with the measured increase in night time temperatures that is the whole basis for trying to find (and coming up with CO2) a suggested cause.

Really. Go research.

Re:I think the first AC

[Anonymous Coward]

You sound new to /.

Hello Capt. Obvious

[DaMattster]

I wish I could tag this one as duh. Weather is bound to be generated when you pass a hot jet engine through a cold cloud. Not to mention the heat of the fuselage generate from air friction. Although, I was impressed that several inches of snow has the potential to form.

Re:Hello Capt. Obvious

[Anonymous Coward]

The fact it's hot doesn't mean too much. It could be lukewarm at those elevations. The key ingredient is water vapor generated by the combustion of jet fuel. And you get a lot from it! That released hydrogen loves to bind to oxygen after all ;)

Re:Hello Capt. Obvious

[evilviper]

I wish I could tag this one as duh. Weather is bound to be generated when you pass a hot jet engine through a cold cloud. Not to mention the heat of the fuselage generate from air friction.

Give yourself a "duh" there, because a quick reading of TFA reveals you're wrong in every respect as to the mechanism.

For example, turboprops are more significant contributors, precisely because they are more efficient, and less "hot". And there's little effect on very cold clouds, it's the in-between ones which get pushed to the tipping point.

Attention! Warp Restrictions Are Now In Effect

[Anonymous Coward]

Oh...wait... wrong millennium.

the short D20 version of this (its a dice roll)

[RobertLTux]

to create a rain/snow storm in a given area certain things have to happen

lets say you need to roll 60 on a d100 to get rain and roll a 4 (on a d6) to get snow IF YOU ROLL RAIN

just dartboarding a few factors you need to have
greater than X% humidity (add 7 to your roll for every 10% above X)
a cold front near by to generate the clouds (and provide for some winds) (add 2 for every 1.5 degree difference)
enough seeds in the clouds to tilt things past the equalibrium
a low enough temp that the water doesn't boil off (penalty of 1 on the d6 roll for every 20 degrees above 0C)

now having a bunch of planes i would bet could 1 add to the "muck" in the air 2 twist the temps a bit 3 do a whole lot more than a butterfly in generating wind

We already knew this from ST:TNG.

[Anonymous Coward]

Didn't these scientists watch where Picard learns that warp drive destroys the time space fabric?

I don't understand the Karma System

[mlawrence]

I had neutral Karma, then I made the first post here (currently at +4 Funny) and now I am bad karma. Don't know where else to post this question. :) Martin

Re:I don't understand the Karma System

[Anachragnome]

The Slashdot moderation systems is a system of layers.

Users are randomly assigned "moderation points" that can be spent moderating a post upwards "+1", or down with "-1" and include a "tag".

Once spent, the points are painted onto ping pong balls--"+" balls and "-" balls. These are then thrown together in a large hopper and fed down a tube to the squirrel cage. In this cage, dozens of specially trained squirrels sort the ping pong balls according to size and shape and drop them down appropriate tubes to be further sorted by the next stage of squirrels. Once fully sorted, each ping pong ball is individually routed through a pipe that determines the tag that will be applied. The ping pong balls are then routed back to the beginning of the system. The ping pong balls are siphoned off from various points throughout the system at the same rate that posts are made. Each ping pong ball is then assigned to a random post, and there ya have it--Slashdot moderation.

I hope that helps.

Re:I don't understand the Karma System

[Anonymous Coward]

Some grinch modded your post -1,Overrated.

Re:I don't understand the Karma System

[Anonymous Coward]

Indeed. You don't get positive karma from Funny-moderations. You do, however, get negative karma from Overrated-moderations. Thuse +4 Funny, -1 Overrated is a net negative yield.

Yes, it's bizarre.

Cooling?

[pookemon]

I find it a little odd that TFA talks about how an aircraft flying through a cloud causes it to "cool", resulting in the supercooled liquid suddenly freezing. There's a very well known phenomenon with supercooled water where it will remain in a liquid form, until it comes into contact with ice crystals. I would think that that was a far more likely cause of the clouds suddenly being filled with ice rather than a jet or turboprop "cooling" an already supercooled cloud.

My 2c

Forcing

[ShakaUVM]

>>The contrail cover from planes reflect more light from the sun.

Also, it's important to state that up until this point, climatologists thought that contrails had a forcing effect helping to cause global warming. And still show it that way, for example: http://en.wikipedia.org/wiki/Radiative_forcing

However, papers like this: http://www.nature.com/nature/journal/v418/n6898/full/418601a.html rather convincingly argued that they have a rather strong forcing in the opposite direction (i.e. that they help to dim sunlight more than they trap heat).

While honest climatologists will admit that some areas in AGW are very well understood, and others are much less understood, dishonest climatologists will pretend that they know everything and how dare you for questioning the global warming groupthink. In fact, how they respond to reasoned criticism is often a clear giveaway as to which camp they fall into.

Re:Forcing

[Abcd1234]

Yeah, pity you're actually reading the fucking results wrong. *sigh* To quote wikipedia:

Measurements showed that without contrails, the local diurnal temperature range (difference of day and night temperatures) was about 1 degree Celsius higher than immediately before

The daytime temperature didn't increase. The difference between night and day increased. And guess what? That matches expectations! Why? Because:

Other studies have determined that night flights are mostly responsible for the warming effect

So when there are contrails, it stays warmer at night, due to radiative forcing effects. No contrails? It gets colder at night. End result? *Larger night-day temperature difference*.

But, hey, let's actually look at your study, shall we? Hey, here's a choice quote from the abstract:

Because persisting contrails can reduce the transfer of both incoming solar and outgoing infrared radiation4, 5 and so reduce the daily temperature range, we attribute at least a portion of this anomaly to the absence of contrails over this period.

Hey, look at that... that's what they fucking found. Science at work: scientists make prediction. Scientists have convenient experiment. Observations match predictions. The system works.

But, hey, don't let facts get in the way of your "skepticism".

Re:Forcing

[shadowbearer]

  What's really amazing about all the data there is that it showed that even over a very short span of time a suspension of one part of human activity had an effect on our climate.

SB

Re:Forcing

[ShakaUVM]

No problem. I'll see if I can dig up a better paper for you. From what I recall, the average temperatures went up as well, ~2.0 C

Re:Forcing

[Anonymous Coward]

While honest climatologists will admit that some areas in AGW are very well understood, and others are much less understood, dishonest climatologists will pretend that they know everything and how dare you for questioning the global warming groupthink. In fact, how they respond to reasoned criticism is often a clear giveaway as to which camp they fall into.

Posted anonymously by khayman80 (Dumb Scientist) from an internet cafe in Koh Phi Phi Don.

I'd like to thank Abcd1234 for once again reducing my workload- especially during my vacation. But this statement is doubly redundant because (1) All climatologists I've met or researched have been honest (defined as PhD physicist specializing in a range of subfields related to climate prediction or paleoclimatology.) and (2) all scientific fields have areas that aren't well understood.

(Of course, if you'd said "members of the general public who identify with the Green party, I've already repeatedly agreed with you. But you didn't.)

In fact, climatologists express how "well understood" an effect is by the error bars on the radiative forcings chart. The larger the error bars, the "less understood" the effect is. That's just the way all natural science is done. Strangely, some pseudoscientists criticize climatologists when their error bars are too small (i.e. pseudoscientists accuse climatologists of pretending to know everything) AND when their error bars are too large (apparently that means they're deliberately avoiding falsification.)

Do you have any reputable citations showing professional climatologists engaging in groupthink or responding badly to reasoned criticism? I ask because, once again, your description of the climatology community sounds like a description of a cult...

Re:Forcing

[ShakaUVM]

>>responding badly to reasoned criticism

You mean like how they circled the wagons around Phil Jones, even when actual bad behavior on his part was discovered?

For example;
"This has some similarity to the CRU email theft, where precious little was discovered from among thousands of emails, but a few sentences were plucked out of context, deliberately misinterpreted (like "hide the decline") and then hyped into "Climategate"."
(http://www.realclimate.org/index.php/archives/2010/02/ipcc-errors-facts-and-spin/)

Or you can just read the editor's comments left in the response sections of RC.org. Just skimming through that above article, here's an interplay between Pielke and Stefan:
http://www.realclimate.org/index.php/archives/2010/02/ipcc-errors-facts-and-spin/#comment-159627

Or the tendency for certain climatologists to throw out offensive notions like the Salem Hypothesis when someone disagrees with them.

>>In fact, climatologists express how "well understood" an effect is by the error bars on the radiative forcings chart.

To a certain extent you can do this. If you have a positive or negative feedback cycle that is poorly understood, error bars become so large as to be meaningless. For example, if all the ice in Greenland suddenly slides into the ocean next week, it would create a global catastrophe that would lead to various situations well outside of our confidence levels.

Re:Forcing

[khayman80]

That's the third time you've accused me of being dishonest. I'll add these repetitive comments to the huge list you've repeatedly demanded that I answer lest I be considered dishonest. This will take ~10 hours, and consist of ~10 pages of statements like "I've already answered this here, here, and directly to you here, and this is the text: ...."

I'll only post this redundancy to Slashdot (and Dumb Scientist) with the expectation that you'll have the courtesy to finally explain (in a similar point-by-point fashion) why you think this comment is filled with strawman arguments (which, if true, would mean I'm a drooling idiot or a deceitful hack...)

Re:Forcing

[ShakaUVM]

>>That's the third time you've accused me of being dishonest.

We'd never even talked about the Phil Jones issue before, so your attempts to avoid answering it (because you'd answered it before) were indeed dishonest. You've now answered that question, but there's three to go. Just a short paragraph answer to each one please - I won't call you dishonest for not thoroughly referencing your summary, but I will if you keep saying you've answered them before, because I'd never *formulated* them in summary before.

As to your strawmen arguments:
"You're just innocently pointing out that they're bullshitting deceitful hacks who aren't scientists any more than economists are"

Uh, no. Since you've ostensibly read my posts before, you know that I was very careful to say that I don't think that people like RC.org are generally deceitful, but rather politically biased (yes, "hacks"), shooting withering attacks on anyone that disagrees with them, and yet giving free passes to people like Al Gore or Phil Jones. Occasionally I think climatologists' arguments are wrong (like RC.org and your stance towards Watts), but overall I don't think there's any great conspiracy to invent AGW or anything like that.

Since you like to reference my posts mirrored on your own website, you should see that I've said this repeatedly, even in the post you quoted above:
http://dumbscientist.com/archives/abrupt-climate-change#comment-1537

If you want to take a shot at defending the mistakes in An Inconvenient Truth, let me know. RC.org was borderline lying on some of its points on the movie.

In any event, you shouldn't take offense at being lumped in the same category as economists, in terms of observation, modeling, and prediction, economics is the closest field to climatology. The point I was trying to make is that if climatology is science, the economics is science. If economics is not science, then climatology is not science. Or to put it another way, I think we need new labels for a category somewhere between hard science and social science.

"Do you think I've repeatedly insulted myself, or have I simply been honest about my credentials?"

No... but referencing the Salem Hypothesis (a reference to Creationism) *was* insulting. I don't mind if you were offended I lumped you into the same category with economics, but I think the field is closer than you might think.

"Second, you mentioned the "0.3C per decade" prediction from emission Scenario A, but you've repeatedly [dumbscientist.com] ignored Scenario B which Hansen himself called "more plausible" in 1988."

That's great, but I'm not talking about Hansen88, but AR1, which focuses on Scenario A. It's possible this was done to scare politicians into action, but when one reads it, the +0.3C increase appears to be the best guess.

"You accuse Gavin Schmidt of being a bullshitting deceitful hack who isn't really a scientist."
"It's interesting that you claim physicists who study the climate are inflating their error bars in a blatant attempt to avoid falsification"
"...which obviously means he's deliberately inflating them to avoid falsification."

You wanted to know which statements were strawmen? These are some more.

You've missed my point repeatedly on error in predictions, so I'm not going to bother repeating myself again. (See how annoying that is, when someone does that?)

Re:Forcing

[khayman80]

That's the fourth time you've accused me of being dishonest, and of not really being a scientist. I tried to tell you twice that economics involves people who have free will but radiative physics involves molecules which don't have free will (unless you're a pantheist, I suppose) but you haven't even peripherally answered that point, and I've long since lost interest.

Your reading of AR1 yet again misses the point that climate models are dynamical, not empirical. So the entire reason for giving different scenarios is to account for uncertainty in human pollution, solar activity, volcanism, etc. As Gavin pointed out, the projected forcings assumed in scenario B were actually slightly too high compared to reality, so scenario B is a slight overestimate. But that uncertainty is compartmentalized away from the GCM uncertainty.

If you want to take a shot at defending the mistakes in An Inconvenient Truth, let me know.

Huh?

I'm now convinced that you're just playing a cynical game to see how much of my time you can waste. I've archived all of your statements in this article, so I'll simply let my readers decide if you called climatologists deceitful hacks who make bullshit claims, aren't really scientists, just make themselves feel better by calling each other scientists and holding "science-y" conferences even though they can't falsify their hypotheses because their error bars "so large you can basically never prove the predictions wrong." Maybe they'll agree with you that these are just strawman arguments which you didn't actually make.

Obviously, this conversation is a waste of time. Let's just agree to disagree, okay?

Re:Forcing

[ShakaUVM]

>>That's the fourth time you've accused me of being dishonest, and of not really being a scientist.

Then honestly answer my four questions. That's all I've been asking for.

The issue about the label of 'science' one is not an attack on you, but rather a philosophical musing on the nature of climatology.

>>I'm now convinced that you're just playing a cynical game to see how much of my time you can waste.

If you spent half as much time actually answering the four questions (and again, I don't need a fully referenced essay) instead of engaging in meta-conversation... well, we wouldn't be having this meta-conversation.

Re:Forcing

[khayman80]

No, you didn't just ask four questions. You repeated many accusations about climatology not being falsifiable science (etc), which where merely grouped into four paragraphs. I've already explained that I have serious OCD and can't answer all these insults without referencing all the times I've already answered the same cynical accusations. Do you seriously think that answering all these accusations for the N'th time is more important than developing an early warning system for tsunamis? I don't. Seriously, let's just agree to disagree. Have a nice day.

Re:Forcing

[ShakaUVM]

>>No, you didn't just ask four questions

Again, instead of talking about all this other stuff, which is incidental, you could just answer them.

>>I've already explained that I have serious OCD and can't answer all these insults without referencing all the times I've already answered the same cynical accusations

Which is completely meaningless to me. I don't care that you don't like the fact that climatology is kinda-sorta science. I don't care this insults you, however it is an accurate description.

That's why I stopped the conversation at that point and formulated four very simple questions for you, which you've refused to answer over and over again. I simply can't understand how you can spend so much time arguing with me, and yet still can't spend the five minutes to define your position on the issues surrounding global warming. It feels like pulling teeth.

Re:Forcing

[khayman80]

I survived my trip through Cambodia, so unfortunately I'll have to spend WAY more than 5 minutes answering your huge list of "philosophical musings", primarily by showing that I've already answered them repeatedly. I will eventually do this, but my actual research has to take priority. I'll post this epic response to your most recent Slashdot post when I'm finished. Until then, please let me focus on trying to not fail out of school, okay?

Re:Forcing

[ShakaUVM]

>>Until then, please let me focus on trying to not fail out of school, okay?

Sure. No worries, dude.

Just one final clarification for you - keep in mind that my comments on error bars were musings on the falsifiability of global warming, from a philosophy of science perspective.

Opposite effect

[GaryOlson]

Anyone who has watched weather fronts as they approach DFW airport can provide anecdotal data showing the reverse effect -- aircraft disperse clouds. Huge storm fronts slam into Fort Worth, the middle dissipates as it approaches and passes over DFW airport, then storm fronts reconnect east to reform a single storm front. How far east depends on the strength of the storm. Or the splitting of the front at DFW airport will cause the storm front to degrade to localized cells. Very few storm fronts survive the impact of DFW airport as a continuous front. YMMV....

Re:Opposite effect

[Anonymous Coward]

Giant stretch of tarmac or planes, which would cause a high pressure zone.

Hmm...

Re:Opposite effect

[forceman130]

I'm guessing that has more to do with the heat coming off all that tarmac than it does with the aircraft themselves.

mod parent up

[bussdriver]

if I just had some mod points

HA! I love "unexpectedly"

[cyber1kenobi]

"Yeah, we didn't think flying these huge things in the air and burning thousands of gallons of fuel would actually do anything..."

Captain obvious fail ?

[billcopc]

I am by no means a weather geek, but it seems obvious to me. You have a cloud, by definition a body of misted water in borderline suspension, and you ram a plane through it, it's going to upset the suspension enough to change back into a liquid. We did stuff like that in science class in high school :P

Re:Captain obvious fail ?

[s_p_oneil]

I agree. All that's needed for precipitation to start is for enough tiny water droplets or ice crystals to collide with each other to make them heavy enough to fall. If the cloud is heavy enough (i.e. close to some saturation point), those drops will bump into others, causing a chain reaction that can go on until the cloud gets too light to sustain the chain reaction. It seems obvious to me that a commercial airliner flying through a cloud at 500+ MPH could start that chain reaction. Whether it actually causes precipitation to reach the ground depends on the cloud and the conditions beneath it, not on the plane.

Re:Captain obvious fail ?

[clone53421]

Indeed. Poking holes in clouds has long been a favourite method whereby to attempt weather control. Usually with cannon or other projectile launching devices, but I see no reason that an airplane would be different. Plus you are, as others have noted, also burning thousands of gallons of fuel...

oh, really?

[Anonymous Coward]

Here in Europe the sky was blue, when the planes were grounded because of Eyjafjallajökull blowing ash into the air. Before and after these groundings, all days with blue sky aren't blue at all but cloudy with a pattern of these clouds that shows they come from planes.

How was it after 9/11 in California?

cb

Ugh. The new deniers use fancier arguments.

[Renegade Iconoclast]

Your post is littered with falsehoods. I barely know where to start. Whether you realize it or not, you're concern trolling from ignorance.

We still do not have enough evidence to prove that burning fossil fuels will produce global warming.

Eh? What?`

First off, basic physics predicts that more CO2 and methane (and other greenhouse gasses) in the air will cause the atmosphere, and hence, the ground, to heat up. In a glass jar, CO2 behaves precisely as expected.

The Earth is more complex than a glass jar, it's true, but to argue against global CO2-based warming, you need a plausible physical explanation for where the heat caused by the CO2 went. Unless some obscuring agent prevents sunlight from hitting the CO2, the heat from was undoubtedly generated in the atmosphere nearly exactly as predicted by physics. So where does it go?

In addition to a magic (heretofore invisible) heat-sink, you need a plausible alternative explanation for the geologic record, dating back 100s of thousands of years, showing that, indeed, CO2 and warming are in a feedback-loop, punctuated by various global disasters.

Now before I continue, let me just get this out of the way: there is a difference between someone who believes global warming *can't* be true in the religious sense, and someone who recognizes that climate is a difficult subject for which we just don't have the answers now.

This is a ridiculous cop-out, and is a lousy argument for destroying civilization as we know it.

The fact is, we've had a pretty nice equilibrium here for thousands of years. Throwing off that balance could mean a lot of different possible things, but it definitely means chaos and turmoil.

We don't know everything, but we know some things. We know that the gulf-stream is very important to heating up North America. We know that North America would turn in to a block of ice if it were to shut down. We may not know how to keep it running, but that's not a good reason to toss a bunch of carbon in the air to see what happens.

The best plan is probably to try to maintain the equilibrium somehow. It's worked for a while. I like the coasts where they are, and I don't want to experiment with their shape, thank you very much. If I were in a rowboat with you, I also wouldn't want you to experiment by standing up and rocking it back and forth.

I'll deal with two more of your arguments.

Global temperatures have been on the decline for the last decade, much as they did during the turn of the century 100 years ago.

Incorrect. 1999-2009 were the hottest decade in human history. 2009 was about as hot as the previously hottest year on record, 2005, and possibly hotter, depending on what source you use. This can hardly be described as a decline, and is a typical misconception sponsored by various media outlets.

2010 is trading on Intrade at 67% to be the warmest year on record. You could make a pretty nice sum by betting against it, getting back two times your money at that price level.

Only if you cherry pick 1998-2007 from the data can you claim a "decline", which really isn't a decline, it's a squiggle that bounces back and forth, ending up just below the top.

You may not be a denier, but you sure play one on /.

We can probably agree that CO2 is a greenhouse gas; what we can't explain is why increased generation of CO2 hasn't resulted in a proportionate increase in the atmospheric CO2 levels.

Possibly because you made up that as a requirement. Your argument is irrelevant and spurious. Physics predicts a warming as CO2 rises. CO2 levels are rising dramatically, as we have observed. The temperature is rising dramatically, as we have observed, your weak protestations to the contrary notwithstanding.

Yes, the oceans absorb some. This isn't a question as you intimate, it has been measured. The question of whether increased CO2 in the atmosp

Re:Ugh. The new deniers use fancier arguments.

[Troed]

Your post is littered with falsehoods. I barely know where to start. Whether you realize it or not, you're concern trolling from ignorance.

(I'm sure you believe everything you wrote in your post above. That in itself doesn't make it true.)

CO2 absorption is logarithmic. CAGW rests _completely_ on speculated (and unsupported) positive feedback.

As to the errors: No, the geologic record does not show what you claim. No, we haven't had a nice equilibrium.

Oh, yeah

[shadowbearer]

  The Slashdot moderation systems is a system of lawyers. FIXED.

As someone who has no damned clue why I seem to get randomly assigned either 5 to 15 moderation points, your explanation makes as much sense as any other.

  This year has been really weird. It seems that the more I post, the more mod points, but the more I post, the fewer mod points, varies from week to week ;_)

  If that seems somewhat redunant, see Rule #34 about mod points: Don't talk about moderation assignations. There may even be Content involved! Nah...

  This is what happens when human beings relinquish control of voting to corporate algorithms. Oh, wait, wrong forum...

  I'm damned now, I've divulged Secrets. It was good to know ya'll...

  (Finger)

  "Karma:Excellent" for more than seven years, now. "Friends" capped. It's Fucking Meaningless.

  Smite me, Oh Overlords, Please. Give me a good reason to dump this addiction.

  Fuck. you. Corporate. Whores. If you want yes-men, you won't find them here. Go live in your little world.

  Salut, Anachragnome. Thanks. Irony bites, don't it?

SB

Poor rebuttal

[YuppieScum]

I feel that any rebuttal that begins

To quote wikipedia:

is inherently invalid.

Re:Poor rebuttal

[Abcd1234]

is inherently invalid.

You feel wrong. Wikipedia provides an excellent overview of current literature on the topic. If you doubt that overview, you're free to read the rather long-ish list of cited papers and other sources on that page.

Re:Poor rebuttal

[YuppieScum]

You appear to not understand the difference between an opinion and a statement of fact.

Re:Poor rebuttal

[Abcd1234]

Hmm, very well, let me rephrase: Your opinion is idiotic.

Better?

Not too bright

[hesaigo999ca]

The plane's engine exhaust is hot enough to create a slight precipitation enough to destabilize the cloud and make it pop so to speak, whether it is hot air masses created by mother nature or by planes, the same result happens, but with planes it is small compared to the bigger mother nature kind, so technically will not rain or snow for that long...China used a sort of similar weather control system during the Olympics, to help maintain the raining season...what they did helped, but only a little...it still rained...just not as much.

This is hardly news worthy science, however does let most people realize that it is possible and not magic to control the weather, we just need a bigger delivery system and power source...maybe like a gigantic zeppelin....i wonder if the side of the zeppelin was made of materials that took the heat from the sun (solar panels???) and stored it to use for later, within a cloud mass.....if it would work....if only i had millions to research with.....ah well..

another kind of precipitation

[juan2074]

Also, watch out for the blue ice.

I knew it...

[Anonymous Coward]

Chemtrails!

Ah, science philosophy writ modern

[shadowbearer]

Thank you for the formatting. I realize it's hard...

But humans are the result of natural processes in the universe, and if you wish, the leather shoes they create are also the result of a long history of transitions between thermodynamic states.

  That's philosophy, not science. While both exist within the universe, it doesn't follow that the creations of human imagination follow the rules of the universe. There are plenty of examples which show otherwise.

  So on one hand you are offended by some statement I made that you claim smells faintly of creationism (I'm sorry, but I really don't know how you came to this conclusion), and in the statement above you seem to claim that the universe had no part in the creation of leather shoes. So what are humans? Supernatural? Not part of the universe?

  Human beings have dreamed up all sorts of silly stuff that obviously has no basis in reality. Much of it currently seems to determine our course as a species, even in the face of massive amounts of evidence which shows that we are in fact being very, very stupid.

  The fact that I can't find a local cobbler who can produce shoes to fit my 13W feet doesn't reflect on the basic laws the universe operates under.

  Doesn't make it any less of a fact - just means it has nothing to do with the universe writ large.

  "Experimental design" doesn't necessarily reflect reality, either - it can and has been taken too far; one can design experiments that are totally logical within the framework of the lab, but have little if any relevance to the world outside the lab. There are numerous examples of that.

  You might have to figure out the rest of my refs on your own. Irony and Sarcasm are a dying lingual art, it seems.

  Hint: Mathematics rarely describes reality, even when it does.

SB
  "Nothing the god of biomechanics wouldn't let me into heaven for"

Re:Ah, science philosophy writ modern

[Anonymous Coward]

Well, I really appreciate the response. I'm afraid that I just don't understand the point you are trying to get across. This thread ultimately has been about whether or not it is possible to perform a designed experiment on a complicated natural situation (clouds). I argue that this can be done, using commonly accepted methods widely used in the scientific community. After all of this, I'm still not sure what you are arguing for, or how what you have pointed out are reasons why the designed experiment is impossible.

I'm not really concerned about the creations of human imagination (I assume this includes gods, star trek stuff, etc.) that don't actually exist, but am concerned with actual physical things in the universe - clouds and different kinds of leather. We perform experiments on them. If you want to make existential arguments about what the universe cares about, or whether mathematics can be used to describe reality, that's fine, but that is an entirely different topic than what this thread is about.

Irony and sarcasm are probably not a dying art, but your presentation of either went over my head. I hope we all feel better now.