The Kalahari Desert is a large semi-arid sandy savannah in Southern Africa extending 900,000 square kilometres (350,000 sq mi), covering much of Botswana and parts of Namibia and South Africa. As semi-desert, with huge tracts of excellent grazing after good rains, the Kalahari supports more animals and plants than a true desert, such as the Namib Desert to the west.
The Kalahari Desert is formed in a region of subsidence in the Hadley cell known as the “horse latitudes” and also its continentality, but the cause of the Namib desert is the cold Benguela current in the Atlantic ocean. There are small amounts of rainfall and the summer temperature is very high. It usually receives 3–7.5 inches (76–190 mm) of rain per year.
The surrounding Kalahari Basin covers over 2,500,000 square kilometres (970,000 sq mi) extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe.
The only permanent river, the Okavango, flows into a delta in the northwest, forming marshes that are rich in wildlife. Ancient dry riverbeds—called omuramba—traverse the central northern reaches of the Kalahari Desert and provide standing pools of water during the rainy season. Previously havens for wild animals from elephants to giraffes, and for predators such as lions and cheetahs, the riverbeds are now mostly grazing spots, though leopards and cheetahs can still be found. Among deserts of the southern hemisphere the Kalahari Desert most closely resembles some Australian deserts in its latitude and its mode of formation.