[air-gloh] 
| a dim light from the upper atmosphere caused by emissions from atoms and molecules ionized by solar radiation: observed at night (nightglow), during the day (dayglow), and at twilight (twilight glow), with each having slightly different characteristics. |
| airglow (âr'glō') Pronunciation Key
A faint photochemical luminescence in the upper atmosphere caused by the collision of x-rays and charged particles from the Sun with atoms and molecules, especially of oxygen, sodium, and the hydroxyl radical (OH). Airglow is strongest over low and middle latitudes. |
twilight glow
weak, widespread, and relatively steady glow from the sky that is observed around twilight; it is part of the overall phenomenon called airglow (q.v.).
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