What causes the compression of air on the leeward side of a mountain?

The compression of air on the leeward side of a mountain is primarily caused by high pressure systems. As air ascends the windward side of a mountain, it cools and expands. This process can lead to the formation of clouds and precipitation. When the air descends on the leeward side, it warms due to compression as the atmospheric pressure increases. This warming effect occurs because as air sinks, it is subjected to higher pressure, which causes it to compress and thus increase in temperature.

This phenomenon is often referred to as the rain shadow effect, where moist air loses its moisture on the windward side of the mountain, resulting in drier conditions on the leeward side, where the compressed air creates high pressure. The result is typically clear skies and warmer temperatures on the leeward side. Understanding this process is key in weather patterns and landscape differences in mountainous regions.