Gravity has very little to do with it. Trust a Yank to get it cockeyed!
Its a dynamic wave.
In the Northern Territories of Oz, Gulf of Carpentaria, the soaring pilots have explored what are sometimes 1000km long mile high pressure pulses that roll across the area. Usuing sailplanes they have surfed these waves much like an regular surfer does on ocean waves.
A fancy name for the air equivalent of a humble standing wave - great news for glider pilots. They are seen regularly east of the Cairngorms and the Welsh mountains. Love the time lapse!
Wasn't Melvin Bragg talking about gravity waves last week (when I say "talking" I mean listening to experts) I believe they are pulses of gravity caused by non-symetrical events, and a recent supernova gives these boffins a chance to measure some. They are not clouds.
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Standing waves are a little different. They are pretty much stationary like the wave over an ostacle in a rivercourse. The dynamic waves in the video clip travel across the ground like a wave in the sea.
Brilliant - "look it's a Gravity Wave" - gotta love the Internet!!!
I wouldn't be surprised if there's a ridge (a long hill, not a high pressure thingy) just upwind and out of picture. It looks more like a layer of Cumulostratus that's being lifted and dropped by ridge lift to me.
It wouldn't be standing wave unless the same air mass rose and fell and a couple of times.
It's be interesting (to me anyway) to hear Simon Keeling's comments on this. Standing waves do move quite a lot as the windspeed varies - not sure why but they definitely do. The height of the stable layer of air above that reflects it down can vary as well. Frontal wave, where the wind rises over a sea-breeze front or similar is pretty common too.
Pretty useless at sea though, unless you're an albatross.
Flown hang gliders in standing wave on Merthyr Common and the like several times, where the standing wave amplifies over the parallelish hill ridges and valleys.. Exhilarating fun
Solitons travel through their medium, and as they do in some manner get energy from their medium so that they self-reinforce. Standing waves don't do that.
Having been looking up about mammatus (clouds, not anatomy) I discovered that Gravity Waves is indeed a term used in fluid dynamics and and is used in meteorology to describe standing waves. See here. Nothing to do with Gravitational Waves which is the quantum physics thing I immediately thought of.
I will now go and stand in the corner wearing a pointy hat for the rest of the day.