What happens to air as it rises over mountains?

• A. It sinks and warms the surface
• B. It disappears at the peak
• C. It cools and condenses, forming clouds and precipitation
• D. It heats up and dries the air

Answer: (C)

When air rises over mountains, it expands as the surrounding pressure drops with height. This expansion uses energy and cools the air (adiabatic cooling). If the air cools enough to reach its dew point, water vapor condenses into tiny droplets, forming clouds; with enough moisture, those droplets grow and precipitate as rain or snow. So rising air leads to cooling, condensation, and often cloud formation with precipitation, rather than disappearing or heating and drying the air.