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by greglindahl 3443 days ago
Gravity is one of several forces that may act on what's going on, but the cause of the wave is the initial perturbation, which isn't gravity. Put another way, if I have a steady-state hydrostatic system, gravity waves won't just spring into existence. You need that initial push.

In this case, the initial push seems to be wind hitting a mountain and being forced up.
2 comments
simonh 3442 days ago
> gravity waves won't just spring into existence. You need that initial push.

The gravity wave that causes tides on Earth requires no such push, it's just straight up deformation of the oceans by Lunar and Solar gravity.

> In this case, the initial push seems to be wind hitting a mountain and being forced up.

Where did you get that from, the body of the article? It's not in the abstract, which only talks about gravitational effects.

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contravariant 3443 days ago
You need the medium, gravity, and 'push' to get a wave. Calling them <medium>-wave, or 'push'-wave doesn't really tell you anything useful, so they're called gravity-waves. An alternative would have been buoyancy-wave, but apparently this didn't catch on (buoyancy and gravity are really two sides of the same coin, anyway).
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Godel_unicode 3442 days ago
Buoyancy is related to density, which is independent of gravity. Check: buoyancy can exist in a non-inertial reference frame provided acceleration in a "downward" direction.

Also, you don't need gravity to be the force being acted against in order to form a wave. You can get impact waves in water at 0g because of surface tension.

https://en.m.wikipedia.org/wiki/Buoyancy

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