Question

The air of the atmosphere becomes cold at higher altitudes due to :

• A. decrease in density
• B. variation in pressure
• C. expansion of the air
• D. height above the surface of the earth

Answer 1

The correct option is C expansion of the air

Firstly the air near the surface heats and hence rises up. As air rises, air pressure drops and the gas expands. To expand, the gas needs energy which it robs from the surrounding matter. This cools off the surrounding air. Hence it becomes cold at higher altitude. This effect is similar to that of a gas coming out of spray. It cools due to rapid expansion.