Determine in which areas of the Earth the average annual rainfall is less than 100 mm and more than 300 mm

A) less than 100 mm. Sahara Desert (Africa), Arabian Peninsula
B) more than 3000 mm. Andes Cherrapunji Foothills (India)
Explain the reasons for the uneven distribution of precipitation on our planet.
The main reason is the placement of low and high atmospheric pressure belts. (It also depends on the position of the terrain relative to the World Ocean, on the proximity of the terrain to ocean currents, on the topography)