Here's why:
* Windward side: This is the side of the mountain facing the prevailing wind. As air rises up the slope, it cools due to expansion (adiabatic cooling). This cooling often leads to condensation and precipitation on the windward side.
* Leeward side: The air descends on the leeward side of the mountain, becoming warmer due to compression (adiabatic warming). This results in drier conditions on the leeward side.
This phenomenon is known as the rain shadow effect.
