I’m always talking about the beauty of the night sky.  Those of you who live away from the city lights are often treated to quite a show.  Last night, Barry Burgess, a regular “Snapshot” contributor, was fortunate enough to photograph something that many of us have never seen: airglow.   It’s possible that you’ve seen it and wondered what it was.

Airglow is sometimes called nightglow.  It’s a faint light emitted from our atmosphere. It’s the light of electronically or vibration-rotationally excited atoms and molecules, 80 km of higher.

The sun’s extreme ultraviolet light excites oxygen and nitrogen atoms and molecules in the thermosphere (an area of the atmosphere characterized by an increasing in temperature in height). The molecules and atoms collide and interact with the other atmospheric components to eventually produce light emission by chemiluminescence.  Airglow is not always uniform.  It can have bands and patches that shift and vary every few minutes. Gravity waves reaching up from the lower atmosphere, modulate the atmospheric density, temperature and composition and subsequently, the airglow’s intensity.

People often ask if airglow is the same as northern lights. It is not.  While the two occur at similar heights, auroras get their spark from high-speed electrons and protons in the solar wind that bombard oxygen and nitrogen atoms and molecules.

By the way, Airglow is not new.  It was first identified in 1868 by Swedish physicist Anders Angstrom.

The science of the atmosphere is complex and beautiful!

 

Chief Meteorologist

Cindy Day