foehn


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Related to foehn: föhn, chinook wind, FOEN, fohn

foehn

(fān, Ger. fön), warm, dry wind that occurs on the leeward slopes of a ridge of mountains. The term was originally applied to a wind of the Alps but is now used as a generic term for all winds of this type. In other parts of the world the various foehn winds have often been given local names, e.g., the chinookchinook,
warm, dry air mass that descends the eastern slopes of the U.S. and Canadian Rocky Mts. after having lost moisture by condensation over the western slopes. Chinooks occur mainly in winter.
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 over the eastern slopes of the Rocky Mts., the "sky sweeper" over Majorca, and the aspre over the Garonne plain of France. A foehn originates as follows: Air is first forced upward over the windward mountain slopes, cooling as it encounters the lower pressures of higher altitudes. If, however, it reaches its condensation temperature, the cooling is somewhat reduced owing to the release of latent heatlatent heat,
heat change associated with a change of state or phase (see states of matter). Latent heat, also called heat of transformation, is the heat given up or absorbed by a unit mass of a substance as it changes from a solid to a liquid, from a liquid to a gas, or the
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 that results from water vapor condensing into liquid water. As the air flows downward over the leeward slopes, it is warmed as it encounters the greater pressures of lower altitudes. This warming, however, is greater than the cooling that occurred during the ascent if heat was added to the air as a result of condensation, so that the air is both warmer and drier than originally. The foehn occurs when the circulation is strong enough to force air over the mountains in a relatively short period of time. The nature of the foehn in a particular locale depends on the topography, the strength and direction of circulation, and the moisture supply on the windward side of the mountains. The chinook, for example, generally blows from the southwest and sometimes raises temperatures by as much as 20°F; (7°C;) in 15 min.

Foehn

 

a strong, gusting wind of high temperature and low relative humidity that blows down from the mountains into the valleys in many mountain systems. The air properties of the foehn can be explained by its adiabatic heating during its descent down the mountain slopes. The foehn usually lasts less than 24 hours, although it can sometimes last up to five days. The change in temperature and relative humidity during a foehn can be extremely sudden and sharp. The foehn has been studied in the Alps, the Caucasus, the mountains of Middle Asia, and other mountainous regions.

foehn

[fān]
(meteorology)
A warm, dry wind on the lee side of a mountain range, the warmth and dryness being due to adiabatic compression as the air descends the mountain slopes. Also spelled föhn.
References in periodicals archive ?
Gale-force winds were observed in southern to southwestern Switzerland, and strong winds were observed at three stations near Altdorf, all located in a typical foehn valley in central Switzerland.
Bromwich, 2012: Regional climate variability driven by foehn winds in the McMurdo Dry Valleys, Antarctica.
When air passes over mountains and the valleys on the downwind side, the area experiences strong and gusty downslope winds, leading to a warmer, drier climate with a longer crop-growing season - known as 'the foehn effect.
The foehn winds coming from the Western Carpathians and reaching the large valleys found in the Tarnave region also have a significant contribution in terms of temperature.
Rafael Cortes, Marketing Manager for Foehn said, The IP Communications market is very crowded, noisy and fast moving and can be confusing for anyone interested in reviewing and procuring products and services for their organization.
In the 1946 play, the Count of Foehn is convinced his ruler is a chimera, one more creature straddling the boundaries between different species (1128).
As a consequence of the Foehn or Fohn effect (Oliver 2005), whenever such conditions are present in Costa Ricas's Caribbean watershed, the Pacific coast usually remains drier, windier and warmer (Alvarado 2001).
In the evenings, the much-dreaded Foehn (dry, down-slope wind) rustles the leaves of the ancient, gnarled trees dotting the course.
Pascal Foehn, Head of Strategic Marketing at Avaloq, adds "we feel our position in the IRCB 2011 report reflects the ability of the Avaloq Banking System to not only meet the needs of private banks but also to prevail in the retail and universal banking sectors.
Call it what you will--Chinook, Santa Ana, Foehn or Borea--pilots who live in the lands of seasonal high winds know they must either learn to fly in them or sit grounded and watch the world blow by.
Twice Lucky 7g Mtoto - Foehn Gale Sue Smith 0993-9U RPR 80h OR 84h He has not shown a huge amount.