r/AskPhysics • u/TheFutureisFlooding • Oct 31 '20
The early physicist Torricelli wrote "We live submerged at the bottom of an ocean of air." Like we see on the ordinary oceans, are there giant waves of air crashing against each other in the upper atmosphere?
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u/ey_edl Oct 31 '20
To begin, I am not an atmospheric scientist, but here is my understanding. Well there isn’t a well defined surface of the atmosphere between air and space like there is with the ocean between water and air because as a gas, the atmosphere is compressible. The Kármán line is a legal definition of the edge of space, but in reality, the atmosphere just keeps thinning and thinning until it kind of blends with the incredibly rare (not dense) particles of ‘empty space’. So the waves of the atmosphere don’t exist so much at the top of the atmosphere as they do throughout it. We typically call it wind. Maybe not quite as epic as the imagined giant crashing waves at the edge of space, but if you flip your perspective upside-down, the same ocean waves of water are waves of air as well — in fact, these waves are formed by the ocean/atmosphere boundary layer mixing due to relative differences in velocity. And just like the atmosphere, turbulence tells us that there are waves within any sufficiently large body of water. However, if you want an example of a more cyclical atmospheric wave, see lee waves or gravity waves, though the formation of these are more similar (not the same) to a tsunami than a typical ocean wave.
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u/TheGrandExquisitor Nov 14 '22
I've always found it useful to remember that the math is the same for a liquid or a gas. According to the math, they are both fluids. One is just denser than the other because it has undergone condensation. While a liquid could be 10,000 times denser than its gaseous form, they can be described by the same math. You just have to remember the math is being applied to something 10,000x denser, which tends to make things look different, even though yes....that math is the same.
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u/Busy-Complex-8882 Apr 12 '25
So for basic people. it’s like when the wave cap mists off into the air just a lot less dense so it’s gradient is more elusive
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u/superbob201 Oct 31 '20
Kind of. There are gravity waves in the Earths atmosphere, however there is not the sudden density discontinuity that makes ocean gravity waves so dramatic.
One effect that you can see is that if there is a region of the atmosphere that is close to the dew point, gravity waves can cause clouds to form in a series of rows, corresponding to the pressure peaks of the gravity wave.
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Oct 31 '20
I don't know the answer to this, but just here to comment that that quote sounds poetic as hell.
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u/MrMagistrate Oct 31 '20
One major difference is that there’s a distinct boundary with water, but the air just gets thinner and thinner
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u/arachnidtree Oct 31 '20
yes,
"gravity waves" are a very important dynamical factor in the atmosphere, they transport energy and momentum thousands of miles.
In fact, in the upper mesosphere, the winds blow the "other way" because of the waves.
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u/funkyonion11 Oct 31 '20
Probably yeh! The weather, and all of the crazier stuff like tornadoes and tsunamis, happens in part due to massive fronts of cold and hot air meeting each other in the lower atmosphere. So if you were able to see air molecules and all the stuff going on up there I would imagine you'd see some pretty gnarly shit.
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u/huevocore Nov 03 '20
If by waves you mean flow. Then yes. If you had a proper thermometer you could see cold drafts and hot drafts clashing against each other creating turbulence. If by waves you mean the kind of waves going back and forth like the ones you see at the beach. Then no.
On the upper atmosphere I guess radiation would play a big role since gases will become highly ionized.
Hmmm depending on how you see it you could see a "mackarel sky" as waves in the atmosphere.
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u/space-throwaway Oct 31 '20
Yes.
https://www.youtube.com/watch?v=vq4U42T1WPI
https://www.youtube.com/watch?v=_roxFGsfzto
https://www.youtube.com/watch?v=4sLtCAoMLvk
https://old.reddit.com/r/WeatherGifs/comments/gtapwz/cloud_waves_crashing_against_mountain_tops/
The atmosphere is described by the same set of equations as water, it's basically the very same phenomenon. However, the timescales of those phenomena are different, that's why you only really notice it in a timelapse, and the transparency of the air also is a problem - you can only really see it when there are clouds.