Orographic precipitation (meteorology)

Article By:

Lin, Yuh-Lang Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina.

Last reviewed:2005

DOI:https://doi.org/10.1036/1097-8542.YB050200

Mountains may induce precipitation through orographic lifting, sensible heating, instability release, or impinging weather system modification. An orographic precipitating system may form in various ways, depending upon the ambient flow speed, vertical stability and structure of the wind, mountain height, horizontal scale and geometry, and mesoscale and larger (synoptic) environments. The mechanisms of orographic precipitation for small hills and for large mountains are quite different. Over large mountains, the highest rainfall is located on the windward slope of the prevailing wind, while for small hills the highest rainfall is on the hilltops. One revealing example of the rainfall contrast between the upslope and lee slope is the annual precipitation over the Andes in South America, in which the rainfall maximum is located on the eastern slope in northern Andes (to the north of 30°S) and on the western slope in southern Andes.

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