 Wind and moist air is drawn by the prevailing winds towards the top of the mountains, where it condenses and precipitates before it crosses the top.In an effect opposite that of orographic lift, the air, without much moisture left, advances behind the mountains creating a drier side called the "rain shadow".A föhn or foehn is a type of dry, warm, down-slope wind that occurs in the lee (downwind side) of a mountain range.