Katabatic wind

Katabatic wind

A katabatic wind, from the Greek word "katabatikos" meaning "going downhill", is the technical name for a drainage wind, a wind that carries high density air from a higher elevation down a slope under the force of gravity. Such winds are sometimes also called fall winds.

Not all downslope winds are katabatic. For instance, winds such as the foehn, Chinook or Bergwind, are rain shadow winds where air driven upslope on the windward side of a mountain range drops its moisture and descends leeward drier and warmer.

Katabatic winds can rush down elevated slopes at hurricane speeds, but most are not that intense and many are on the order of 10 knots or less.

Examples of true katabatic winds include the Mistral in the Mediterranean, the Bora (or Bura) in the Adriatic, the Santa Ana in southern California, and the Oroshi in Japan.

A katabatic wind originates from the cooling by radiation of air atop a plateau, a mountain, glacier, or even a hill. Since the density of air increases with lower temperature, the air will flow downwards, warming adiabatically as it descends. The temperature of the wind depends on the temperature in the source region and the amount of descent. In the case of the Santa Ana, for example, the wind can (but not always) become hot by the time it reaches sea level. In the case of Antarctica, by contrast, the wind is intensely cold.

Katabatic winds are most commonly found blowing out from the large and elevated ice sheets of Antarctica and Greenland. The buildup of high density cold air over the ice sheets and the elevation of the ice sheets brings into play enormous gravitational energy, propelling the winds well over hurricane force. In Greenland these winds are called Pitaraq and are most intense whenever a low pressure area approaches the coast.

In the Fuegian Archipelago (or Tierra del Fuego ) in South America as well as in Alaska, a wind known as a williwaw is a particular danger to harbouring vessels. It originates in the snow and ice fields of the coastal mountains. Williwaws commonly blow as high as 100 knots, and 200 knot williwaws have been reported. [ Dallas Murphy, "Rounding the Horn" (New York: Phoenix Books, 2004), p. 221. ]

References

* McKnight, TL & Hess, Darrel (2000). Katabatic Winds. In , "Physical Geography: A Landscape Appreciation", pp. 131-2. Upper Saddle River, NJ: Prentice Hall. ISBN 0-13-020263-0

* Brown, Dan (2001). Katabatic Winds., "Deception Point", pp. 197 ISBN 0-7434-9030-4

See also

*Anabatic wind - upslope wind
*Föhn wind
*Williwaw
*Sea breeze

External links

* [http://www.bbc.co.uk/weather/features/az/alphabet31.shtml Weather A-Z - Katabatic Winds By Bill Giles OBE]
* [http://www.alananna.co.uk/blog/2008/ivor-borth-and-ynyslas-katabatic-wind/ Ivor, Wales' very own Katabatic Wind]


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  • katabatic wind — ▪ meteorology also called  downslope wind , or  gravity wind        wind that blows down a slope because of gravity. It occurs at night, when the highlands radiate heat and are cooled. The air in contact with these highlands is thus also cooled,… …   Universalium

  • katabatic wind — noun Any wind blowing down an incline; the opposite of anabatic wind. If the wind is warm, it is called a foehn; if cold, it may be a fall wind (such as the bora), or a gravity wind (such as a mountain wind) …   Wiktionary

  • katabatic wind — noun a wind caused by the downward motion of cold air • Syn: ↑catabatic wind • Hypernyms: ↑wind, ↑air current, ↑current of air …   Useful english dictionary

  • katabatic wind — The cold wind that flows down the slopes of the mountains and spreads at the base of the mountains …   Aviation dictionary

  • Katabatic lift — is a term used by glider pilots to denote a special type of lift formed in valleys when Katabatic winds on both sides of the valley meet, and the air at the bottom is forced upward …   Wikipedia

  • wind — wind1 n. /wind/, Literary /wuynd/; v. /wind/, n. 1. air in natural motion, as that moving horizontally at any velocity along the earth s surface: A gentle wind blew through the valley. High winds were forecast. 2. a gale; storm; hurricane. 3. any …   Universalium

  • WInd — West Indian. Also, W.Ind. * * * I Movement of air relative to the surface of the Earth. Wind is an important factor in determining and controlling climate and weather. It is also the generating force of most ocean and freshwater waves. Wind… …   Universalium

  • katabatic — adjective Etymology: Greek katabatos descending, verbal of katabainein to go down, from kata cata + bainein to go more at come Date: 1918 relating to or being a wind produced by the flow of cold dense air down a slope (as of a mountain or… …   New Collegiate Dictionary

  • katabatic — /kat euh bat ik/, adj. Meteorol. (of a wind or air current) moving downward or down a slope. Cf. anabatic (def. 1). [1915 20; < Gk katabatikós pertaining to going down, equiv. to kata KATA + ba (s. of baínein to go; see BASIS) + tikos TIC] * * * …   Universalium

  • katabatic —   a wind flowing down valley sides and floors, usually as air cools, condenses and sinks at night …   Geography glossary

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