What is Orographic lift?

Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation.

Orographic lifting can have a number of effects, including precipitation, rain shadowing, leeward winds, and associated clouds.