why is it cold in the mountains and hot in the plains?

Answer 1

It is because of the reason that the solar radiation does not directly heat the atmosphere while passing through it.It heats the earth's surface first and the reflected radiation from the earth's surface heats the atmosphere above it by conduction.Thus the atmosphere is heated from below.That is why mountain tops are colder than the plains.

Answer 2

it is becuse of the altitude. the higher you are above the surface, the colder you will feel.

Answer 3

It's because air cools as it rises.