Airglow

Airglow, following a giant thunderstorm over Bangladesh in late April. Giant circular wavelets of glowing air over Tibet, China.   Image © Jeff Dai

The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark.



via APOD