Deserts are mainly found around the Tropics of Cancer an d Capricorn. Deserts are areas of the earth's surface which recieve less than 25cm or 10 inches of rainfall every year. They contain little or no vegetation. As you would expect, temperatures at the equator are highest.
Warm air rises containing evaporated moisture.
The air cools, condenses and forms clouds. The cool, dry air then begins descending. The air warms up. E. Cloudless sky. Because the tropics are largely cloudless they get very hot during the day.