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.

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

[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

[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

[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

[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

[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.

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?

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.

More of a duh, really.

[vandoravp]

They are just giant butterflies, after all.

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?

[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.

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

[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...

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?

[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.

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

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: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: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: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.

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.

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

Poor rebuttal

[YuppieScum]

I feel that any rebuttal that begins

To quote wikipedia:

is inherently invalid.