Foehn wind

A foehn wind or föhn wind is a type of dry downslope wind which occurs in the lee of a mountain range. It is a rain shadow wind which results from the subsequent adiabatic warming of air which has dropped most of its moisture on windward slopes (see orographic lift). As a consequence of the different adiabatic lapse rates of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes. Föhn winds can raise temperatures by as much as 30°C (54°F) in just a matter of hours. Central Europe enjoys a warmer climate due to the Föhn.

Effects

Winds of this type are called "snow-eaters" for their ability to make snow melt (also sublimate) rapidly. This snow-removing ability is caused not only by warmer temperatures, but also the low relative humidity of the air mass, having been stripped of moisture by orographic precipitation coming over the mountain(s).

Föhn winds are notorious among mountaineers in the Alps, especially those climbing the Eiger, for whom the winds add additional difficulty in ascending an already difficult peak.

They are also associated with the rapid spread of wildfires, making some regions which experience these winds particularly fire-prone.

These winds are often associated with illness ranging from migraines to psychosis. A study by the Ludwig-Maximilians-Universität München found that suicide and accidents increased by 10 percent during föhn winds in Central Europe. The causation of Föhnkrankheit (English: Föhn-sickness) is yet unproven. Labelling for preparations of aspirin combined with caffeine, codeine and the like will sometimes include Föhnkrankheit amongst the indications.

Etymology

The name föhn (from the German Föhn, pronounced [føːn]) originated in the alpine region. From Latin (ventus) favonius, a mild west wind of which Favonius was the Roman personification.

Local examples

Regionally, these winds are known by many different names. These include:

• Zonda winds in Argentina
• Chinook winds in the Rocky Mountains, United States/Canada and the Chugach Mountains of Alaska, United States
• The Nor'wester in Hawkes Bay, Canterbury and Otago, New Zealand
• Föhn in Wollongong and South Coast, NSW Australia. Often associated with heavy orographic lifiting on the windward side of the escarpment
• Halny in the Carpathian Mountains, Eastern Europe
• Fogony in the Catalan Pyrenees
• Bergwind in South Africa
• Viento del Sur (Southern Wind) in the Cantabrian region (northern Spain)
• Terral in Málaga (southern Spain)
• Föhn in Austria, southern Germany, German-speaking regions of Switzerland and Northern Italy (even non German-speaking regions)
• Favonio in Ticino and Italy
• The Helm wind, on the Pennines in the Eden Valley, Cumbria, England

In Popular Culture

• Peter Camenzind, a novel by Hermann Hesse refers, at length, to the Alpine Föhn.
• The föhn plays an important part in Dario Argento's film Phenomena.
• The Föhn is used for the letter F in "Crazy ABC's" from the album Snacktime! by the Barenaked Ladies.
• The threat of the Föhn drives the protaganists Ayla and Jondalar in Jean M. Auel's The Plains Of Passage over a glacier before the spring melt. The pair make refereces to the mood altering phenomena of the wind, similar to those of the Santa Ana wind.

Fön trademark

AEG registered the trademark Fön in the 1920s for its hairdryer, which is widely used as a synonym in several languages, such as German, Swiss German, Danish, Italian, Dutch, Norwegian, Czech, Latvian, Romanian, Slovak, Slovenian, Swedish, Turkish and French in western Switzerland.

See also

• Katabatic winds
• Rain shadow

References

• McKnight, TL & Hess, Darrel (2000). Foehn/Chinoonk Winds. In , Physical Geography: A Landscape Appreciation, pp. 132. Upper Saddle River, NJ: Prentice Hall. ISBN 0130202630

Footnotes

External links

• Illustration
• Movie of a Foehn situation in the Swiss Alps