Фён: Горный ветер-тёплый сухой спуск

Type of dry down slope wind occurring near mountains

A Foehn or Föhn (/UK//f//ɜː//n/, /US//f//eɪ//n/ fayn, /usalso//f//ʌ//n//, //f//ɜːr//n/ fu(r)n), is a type of dry, relatively warm, downslope wind that occurs in the lee (downwind side) of a mountain range. It is a rain shadow wind that results from the subsequent adiabatic warming of air that 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. Foehn winds can raise temperatures by as much as 14 °C (25 °F) in just a matter of hours. Switzerland, southern Germany and Austria have a warmer climate due to the Foehn, as moist winds off the Mediterranean Sea blow over the Alps.

The name Foehn (Föhn, ) arose in the Alpine region. Originating from Latin (ventus) favonius, a mild west wind of which Favonius was the Roman personification and probably transmitted by or just fuogn, the term was adopted as In the Southern Alps, the phenomenon is known as Föhn but also and fen in Serbo Croatian and Slovene. The German word Föhn (pronounced the same way) also means 'hairdryer', while the word Fön is a genericized trademark today owned by AEG. The form phon is used in French speaking parts of Switzerland as well as in Italy. The name Föhn was originally used to refer to the south wind which blows during the winter months and brings thaw conditions to the northern side of the Alps. Because Föhn later became a generic term that was extended to other mountain ranges around the world that experience similar phenomena, the name "Alpine föhn" (Alpenföhn) was coined for the Föhns of the Alpine region.

There are four known causes of the Foehn warming and drying effect. Foehn winds are notorious among mountaineers in the Alps, especially those climbing the Eiger, for whom the winds add further 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.

The Foehn was mentioned by Queen's lead guitarist Brian May while talking about the band's grim Munich recording studio experience in 1982. The foehn is attributed by the narrator of Jens Bjørneboe's 1966 novel Frihetens øyeblikk (Moment of Freedom) as the traditional cause of occasional unprovoked murders in a small Alpine town. "Foehn" is the last word in A Nest of Ninnies, a 1969 novel by John Ashbery and James Schuyler. Ashbery claimed that he and Schuyler chose this particular word because "people, if they bothered to, would have to open the dictionary to find out what the last word in the novel meant". Fønfjord, meaning "Foehn Fjord", was named by Arctic explorer Carl Ryder after the powerful Foehn wind gusts blowing during the first exploration of the fjord in August 1891.