Foehn wind
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A Foehn or Föhn, is a type of dry, relatively warm, downslope wind that occurs in the lee 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. 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.
Dissolving Föhn clouds over Cumbre Nueva (1400 m), La Palma
The warm moist air from northern Italy is blocked on the windward side, loses much of its water vapour content, and descends on the French plateau and valley of the Mont-Cenis range in the Maurienne valley.
Rotor cloud revealing overturning and turbulence above the lee slopes of the Antarctic Peninsula during a westerly Foehn event
Foehn clouds upon the Karawanken mountain range, Carinthia, Austria
Rain shadow
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A rain shadow is an area of significantly reduced rainfall behind a mountainous region, on the side facing away from prevailing winds, known as its leeward side.
Effect of a rain shadow
The Tibetan Plateau (center), perhaps the best example of a rain shadow. Rainfalls from the southern South Asian monsoon do not make it far past the Himalayas (seen by the snow line at the bottom), leading to an arid climate on the leeward (north) side of the mountain range and the desertification of the Tarim Basin (top).
The Atlas mountains' (top) rain shadow effect makes the Sahara even drier.
The mountain ranges on the eastern side of Madagascar provide a rain shadow for the country's western portion.