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.
the faint light from the upper atmosphere in the night sky, esp in low latitudes
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.
- Air guitar
an imaginary guitar that one pretends to be playing: a fan playing air guitar along with the band. Contemporary Examples Björn Türoque: Which is more likely to get you laid, air drums or air guitar? The Triumph of Air Guitar Dan Crane October 15, 2009 But Power was disqualified, and rightly so, since it was […]
- Air gun
a gun operated by compressed air. Historical Examples He gets a bunch of things—an air gun, and a train that goes around when you wind her up. The Children’s Book of Christmas Stories Various He had owned the air gun two weeks now, and he hadn’t killed a thing. Frank of Freedom Hill Samuel A. […]
- Air hammer
a pneumatic hammer, usually portable.
- Air harbor
a harbor for hydroplanes, especially seaplanes.