Generic term for the wind that occurs when cold, dense air, chilled by radiation cooling, usually at night, moves downslope gravitationally beneath warmer, less dense air. The occurrence is frequent and widespread in, for example, the fjords of Norway, and as an outblowing wind over ice-covered surfaces in Antarctica and Greenland, where the wind may be extremely strong near the coasts and less severe in many mountain regions. Compare anabatic wind.