Katabatic wind

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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.

A distinction is drawn between winds that are warmer than their surroundings (generally called Foehn or regionally, Chinook, Santa Ana or Diablo) and those that are cooler (for instance the Mistral in the Mediterranean, the Bura (or Bora) 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.