Foehn (Föhn), a sinking air mass which occurs when the air mass flows over a mountain range or the edge of a high plateau and blows down the lee side of the mountains, causing strong gusty winds. When the air mass reaches the valley or the foot of the mountain, its temperature rises and its relative humidity decreases. The foehn does not originate from a warm climate and a mountain range is necessary in order for it to occur. The sinking air mass in the foehn region leads to the dissipation of clouds; for this reason the foehn causes cloud clearing on the lee side of mountain ranges. The foehn wind is found in all mountainous areas. In the Alps two forms of foehn can be distinguished - the "southern foehn" (on the northern flank of the Alps) and the "northern foehn" (on the southern slopes of the Alpine region). Foehns occur most frequently on the direct lee side of the low Alpine passes in spring and autumn. The regions in Austria where the foehn occurs most frequently are the Rhine valley and the region around Innsbruck. The foothills of the Alps are also influenced by the foehn even though it rarely reaches the ground there. Foehns cause mental distress in humans as well as real physical and psychosomatic problems which are also considered to be the cause of certain sociomedical phenomena (increased frequency of traffic accidents and suicides etc.).
Literature: P. Seibert, Der Föhn in den Alpen, 1993.