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Giant Atmospheric Waves Filmed Over Iowa
NJChopperMan writes "For all those of you that thought waves only existed in the ocean, Photos and video of undular bore waves were caught in Iowa last week." The story also touches on the role of undular bores in severe weather, but it's definitely second fiddle to the video of the waves.
i don't know how, but somehow, this is global warmings fault.
If you mod me down, I will become more powerful than you can imagine....
Bore waves . . . in Iowa? *yawn* That sounds about right.
I thought undular bores are those guys at parties who tell loud political jokes then try to sell you insurance or something.
Here's a pretty good example of what this looks like on a weather map
TFA was pretty light on detail, but these look like a completely different animal from the (warning: gratuitous Wikipedia link) mountain waves so beloved of glider pilots. Wonder if they're soarable?
Wow, now I know that the sky refreshes like a CRT now! :)
Jean-Francois Im's blog
Atmosperic wave phenomena have been known for ages, and are hardly inconspicious in those places where they regularly form.
The main "customers" for them are probably glider pilots; as far as I remember, all recent altitude records for soaring have been made using waves formed in mountain regions (14+km), and the current distance record by Klaus Ohlmann (insane 3000+km in one day) was also flown in the waves over the Andes. Thermal updrafts are toys by comparison.
The one thing that you have to hand to the NASA guys is that they indeed caught some very fine specimens there, and in an unusual place, too. Normally, waves are induced by the flow of wind over a given, usually hilly, terrain. Gravity waves from thunderstorm activity are certainly a lot more esoteric, and what they are saying about them being catalysts for storms sounds really intriguing.
A.
...and thus they will both have fluid dynamic behaviors when vibrating (waves) at the interface of another fluid.
Wave action happens at the disturbance interface (involving the propagation of and/or transfer of energy) between fluids of different densities.
The Air/Water fluid interface where one observes common "waves" are observed as water waves because the air is transparent (but it too has waves).
The difference here, is that we have two air masses of different temperatures and humidities (thus having differing densities) interfacing as fluids AND one of them happens to be an air mass that contains visible moisture in the form of clouds.
It is likely that this type of air/air fluid "wave action" happens frequently at the interface between differing atmospheric air masses (AKA fronts), but in this example the clouds made it easily visible.
Nice Image too: http://science.nasa.gov/headlines/y2007/images/undularbore/redgreen_big.gif
http://en.wikipedia.org/wiki/Wave
They already ride the jetstream and save fuel/time on Transatlantic crossings. I forget which direction, but it's around half an hour saving on flight time. That's a /lot/ of fuel.
Operation Guillotine is in effect.
Seriously, go see the photos and video on my blog if you don't believe me at http://rolf.id.au/ We call the resulting visual cloud a morning glory in Australia....
London -> New York 7.5 hrs
New York -> London 6.5 hrs
Given how much I hate long flights I love coming home.
init 11 - for when you need that edge.
The little yacht dithering about in the water under the impact of these waves is, somehow, very endearing. I keep wanting to give it a saucer of milk.
Meta will eat itself
More interesting are the waves set up by the harmonics of the Atlantic Ocean. There's a particular length (I forget exactly, but it's something close to 100 metres) that nautical engineers will never, ever build their ships to be, because they would get torn apart in the middle of the Atlantic by the simple harmonic motion of these waves.
Meta will eat itself
Yes, thats why it's so hard to get rockets into space. A common misconception is that gravity is the limiting factor but in fact it's getting enough speed in a sufficiently sharply pointed rocket to break the airs surface tension which is the major challenge.
I've been a casual cloud/storm nerd for decades and if you watch the sky long enough you can't help but notice "waves" and "drainpipes" at a more localized scale (particularly when a strong cold front is approaching).
I currently live a 100M or so from the beach in Melbourne Australia. Small intense storms come in over the bay heading directly toward the beach so you get the front "ledge" of the storm cloud coming over while behind you is clear and the drama is still out in the bay. If you stay still and face toward one of these storms roughly when the cloud/sky boundry is directly over the beach you will feel the wind do a 180deg flip as if the storm is enhaling warm air and exhaling cold with a slight pause in between. It is more pronounced with slow moving storms and can last for 15 minutes or so with a regular inhale/exhale cycle of about a minute. The first exhale of an intense summer storm can feel like someone opened a fridge door if you have been sitting with your back turned and not seen it approaching.
If rain/hail is heavy enough in the center of the storm you might also see prominent ridges running up the underside of the ledge similar to those in TFA but curved to fit the squashed drainpipe shape of the storm. When the rain/hail gets closer the wind will turn steady and cold (time to go inside).
Disclaimer: Don't try observing it standing on the beach, and escpecially not with an umbrella!
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
I was going to just what you wrote was a complete piece of crap, but I did search before I rashly typed that:
http://www.physlink.com/Education/AskExperts/ae158.cfm
*Snipet*
The value evaluates to be approximately:
11100 m/s
40200 km/h
25000 mi/h
So, an object which has this velocity at the surface of the earth, will totally escape the earth's gravitational field (ignoring the losses due to the atmosphere.) It is all there is to it.
*/Snipet*(Bold is mine)
So while I guess you are theoretically correct, I'm guessing it's only really an issue if you are trying to launch a barn or other non aerodynamic object into space.
This is the first I've heard of that. And it seems to be false. The main issue with getting rockets away from Earth is Earths gravity.
You are modded as insightful, but you give no reference link or any other source of your information.
I don't blame you, I blame the moderators.
Since the NASA site download seems slow right now:
http://youtube.com/watch?v=aako5siSTgM
Some told you that in a bar, and you should not have believed them. Spectral fatigue analysis is a bit more complex than that. Just trying to simulate the random seaway is difficult, search "pierson and moskowitz" for a good start. People get there PhDs just trying to develop ways to get design loads from wave spectrum. Generally these spectrum focus on the North Atlantic wave climate as it is the worst case environment that most boats would ever operate in.
(Think 1980s Flash Gordon)
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