katabatic
kat-ah-BAT-ik
A wind that flows downhill under the influence of gravity, formed when air in contact with a cold surface — a glacier, a snow-covered plateau, a mountain slope at night — becomes denser than the air around it and drains downslope. Katabatic winds range from gentle nocturnal breezes to the 200-mph piteraqs of Greenland.
Etymology
From Greek katabatikos, meaning "going down," from katabainein, to descend.
Notes
The opposite is anabatic — wind flowing uphill, warmed by contact with sun-heated slopes during the day.
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