Mountain ranges in the U.S. create rain shadows, leading to arid climates on the leeward side, where rainfall is significantly reduced.

Rain shadows are a key factor in the formation of arid climates in the U.S. When moist air is pushed up by mountain ranges like the Sierra Nevada or the Rockies, the air cools and loses moisture as rain on the windward side. As the air descends on the leeward side, it becomes dry, creating arid conditions. This phenomenon is responsible for the dry climates found in areas like the Great Basin and parts of California and Nevada, where rainfall is minimal despite being near moisture sources like the Pacific Ocean.