This illustration shows how a rain shadow forms on the wind-protected side of a mountain.
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Image part of the public domain
A rain shadow is a dry region of land on the side of a mountain range that is protected from winds. The protected side of a mountain range is also called the lee side or the down-wind side.
Winds carry air toward the mountain range. As the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. This side of the mountains is called the windward side, and it is where precipitation falls in the form of rain or snow. The windward side of a mountain range is moist and lush because of this precipitation.
Once the air passes over the mountain range, it moves down the other side, warms, and dries out. This dry air produces a rain shadow. Land in a rain shadow is very dry and receives much less precipitation and cloud cover than land on the windward side of the mountain range.
Rain shadow deserts can be found all over the world. Some rain shadow deserts in the United States include the dry land east of the Cascade Mountains in Washington and Oregon, and the Colorado Front Range east of the Rocky Mountains. Rain shadow deserts can be found in other areas of the world, including the Atacama Desert in Chile, which is in a rain shadow created by both the Andes Mountains and weather patterns over the Pacific Ocean.
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