Katabatic wind
A
katabatic wind, from the
Greek word
katabatikos meaning "going downhill", is a
wind that blows down a
topographic incline such as a hill, mountain, or
glacier. Such winds, particularly when they occur over a wide area, are sometimes called
fall winds.
A distinction is drawn between winds that feel warmer than their surroundings (generally called
Föhn or regionally,
Chinook,
Santa Ana,
Bergwind or
Diablo) and those that are cooler (for instance the
Mistral in the
Mediterranean, the
Bora (or Bura) in the
Adriatic or the
Oroshi in
Japan). In more recent times, however, the term katabatic wind usually refers to the cold variant.
The cold form of katabatic wind originates in a cooling, either radiatively or through vertical motion, of air at the top of the mountain, glacier, or hill. Since the
density of
air increases with lower
temperature, the air will flow downwards, warming
adiabatically as it descends, but still remaining relatively cold.
Cold katabatic winds are frequently found in the early hours of the night when the
solar heating has ceased and the ground cools by emitting
infrared radiation. Cold air from
extratropical cyclones may contribute to this effect.
Over
Antarctica and
Greenland, prominent (although unnamed) cold katabatic winds exist, blowing for most of the year.
Winds which blow up a slope are called
anabatic winds.
* McKnight, TL & Hess, Darrel (2000). Katabatic Winds. In ,
Physical Geography: A Landscape Appreciation, pp. 131-2. Upper Saddle River, NJ: Prentice Hall. ISBN 0130202630
*
Anabatic wind*
Föhn wind*
Williwaw*
Weather A-Z - Katabatic Winds By Bill Giles OBE
