How does a rain shadow affect the weather?

A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant-growing, rainy weather. On one side of the mountain, wet weather systems drop rain and snow ... Cool air forms clouds, which drop rain and snow, as it rises up a mountain.

A rainshadow occurs when prevailing winds carry moisture from the ocean, eastward over dry land, dropping precipitation on the windward side of a mountain range. Clouds are forced to rise over the range, causing the air to cool and drop its moisture.