Question

5) When the atmosphere
becomes cool, air pressure is
?​

Answer 1

Explanation:

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.

Answer 2

Because of the difference in density. The air at higher altitudes is more rarefied, meaning that there fewer molecules that are affected by radiation from the Sun, which translates in less energy absorbed for the same volume, which translates into lower temperatures.

Another answer claims that the Sun cannot heat the air because it is transparent; this is true, but for visible light (that’s one of the reason we call it “visible”, by the way). The atmosphere still absorbs good amount of infrared and ultraviolet radiation, which raises its temperature