English: Adiabatic cooling by rising air masses occurs in one of two ways: upward convection or movement up a physical barrier (see figure). The global scale atmospheric convections cells (Hadley, Ferrell, and Polar) cause air masses to rise, generating precipitation due to adiabatic cooling. As an air mass reaches the continent from an ocean (or other large body of water), the air mass is forced upward, in a process known as orographic lift. If the rise of continent is great enough, the air mass will lose all (or nearly all) of its moisture as precipitation on the windward side of the mountain chain. As the air passes over the mountain chain, it is stripped of its moisture creating very dry conditions on the leeward side of the mountain. This process is known as the rain shadow effect, and is responsible for creating some of the world’s driest deserts. Chile’s Atacama Desert is the driest desert in the world due to a double rain shadow effect from two very tall mountain chain (some rain stations have never received measurable precipitation). The Sahara Desert is actually made much drier due the the presence of two rain shadow effects, as well. Rain shadow deserts in N. American include the Mohave, Great Basin, Sonoran and Chihuahuan deserts.