Question

Why are the mountains cooler than the plains in short answer

Answer 1

There is one geographical reason that can explain the differences in temperature of Mountains and the Plains.

Geographically, the height (or altitude) of mountains is very higher comparatively the plains. The plains are at a lower height.

So, as per the normal lapse rate the temperature decreases with increasing height. Temperature decrease at a rate of 6.5 at 1000m height or it decreases 1 degree Celsius at 165 m of height.

Thus, as the height increases the temperature decreases. So going from plains (lower height) to mountains (higher height) the temperature falls making the atmosphere colder.

This is the reason why mountains are colder than plains.