A relatively warm, dry downslope wind on the lee side of a mountain. Condensation and condensate removal during ascent can produce precipitation-driven foehn warming; isentropic foehn drawdown, turbulent mixing and radiative warming can also contribute. Rainfall is therefore not a necessary condition for every foehn event. The atmosphere's upstream stratification, moisture and flow over or around the mountain determine the contributing mechanisms.[ref]
Foehn effect by Met Office. Four mechanisms of lee-side warming and drying
Foehn wind, also spelled "Föhn wind," is a warm, dry wind that descends the leeward side of a mountain range. It is associated with orographic lift, where moist air is forced to rise as it encounters the mountains. As the air rises, it cools and can lead to precipitation on the windward side, but when the air descends on the leeward side, it warms and dries out.
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