I would imagine, from a physics point of view, the gravity wave doesn't
matter, and it's more a question of an unstable wind shear with or
without a density change to support a gravity wave.

I think stability of a wind shear depends on the something obscure
like having no zero of the third derivative of the shear profile.

Once it's unstable, it breaks up into turbulence, with larger
scales in turn breaking up and going to shorter scales, until
eventually it cascades down into heat. That's the stuff you want
to stay out of, if a large shear velocity is involved.

On the other hand, a density change across a wind shear, I have always
suspected, gives nice you herring bone clouds across the sky, where the
fastest growing unstable mode selects out the wavelength. I don't think
they're particularly turbulent.
--
Ron Hardin


On the internet, nobody knows you're a jerk.