Thursday, October 29, 2015
See those green stripes? That is airglow rippled by gravity waves which are disturbances in the troposphere. For example, wind flow over mountain ranges and thunderstorms like in this case.
The airglow is the light of electronically and/or vibration-rotationally excited atoms and molecules 80 km or higher.
So, what's the difference between airglow and aurorae?
Aurorae are at similar heights and are also the light of excited atoms. There is a difference, however, auroral excitation is by collisions with energetic particles whereas daytime short wavelength solar radiation produces the airglow via chemical excitation of which electronically excited oxygen atoms are the main component.