You may be wondering “If deserts are so hot……why are they found along the tropics and not at the equator where the Earth’s temperatures are the highest?”. The diagram below should explain this!
The Hadley Cell
A. As you would expect, temperatures at the equator are highest. Warm air rises containing evaporated moisture.
B. The air cools, condenses and forms clouds.
C. Heavy equatorial rainfall occurs (like in the rainforest!)
D. The cool, dry air then begins descending. The air warms up. Any moisture in the air is held as water vapour (invisible).
Because the tropics are largely cloudless they get very hot during the day. There are few clouds to insulate these areas during the night. Therefore, temperatures drop to very low levels overnight. It’s just like going to bed without any blankets!