The rain shadow effect occurs when moist air rises over a mountain range. As the air ascends, it cools and loses moisture in the form of precipitation, resulting in lush vegetation on the windward side of the mountains. This area receives abundant rainfall, supporting diverse ecosystems. On the leeward side, the air descends and warms, leading to drier conditions. This creates a rain shadow, where the landscape often becomes arid or semi-arid. Regions affected by the rain shadow effect, such as the Sierra Nevada mountains in California, can experience significant differences in climate and vegetation within a short distance.