Orographic Effects on Climate and Vegetation

Mountain ranges reshape regional climate chiefly through orographic lift: when moisture-laden air is forced upward against a slope, it cools, its capacity to hold water vapor drops, and the resulting condensation produces cloud and, frequently, heavy precipitation on the windward side. Once that air crosses the ridge and begins descending the leeward slope, it warms and dries adiabatically, often producing a pronounced rain shadow, a much drier zone in the mountain's lee, sometimes intensified locally by warm, dry downslope winds known as the föhn in the Alps or the chinook in the Rockies. This single mechanism explains an enormous range of the world's wettest and driest regional climates, all governed by the same physics of rising, cooling, and descending air.