Why is the sahara desert so dry?
Atmospheric circulation The Horse latitudes or the Subtropical High are subtropic latitudes between 30 and 35 degrees both north and south. This region, under a ridge of high pressure called the subtropical high, is an area which receives little precipitation and has variable winds mixed with calm. The consistently warm, dry conditions of the horse latitudes also contribute to the existence of temperate deserts, such as the Sahara Desert in Africa, the southwestern United States and northern Mexico, and parts of the Middle East in the Northern Hemisphere, and the Atacama Desert, the Kalahari Desert, and the Australian Desert in the Southern Hemisphere. Having lost most of its water vapor to condensation and rain in the upward branch of the circulation, the descending air is dry. Low relative humidities are produced as the air is adiabatically warmed due to compression as it descends into a region of higher pressure. The subtropics are relatively free of the convection, or thunderstorms
