Africa’s climate and inland waters

Africa is the hottest continent because most of it lies between the tropics, the Sun stands high above the horizon and is at the zenith twice a year. In most places the mean temperature of every month is above +20 °C. It receives a great deal of solar radiation (160–200 kcal per cm² per year). Climate is affected by geographic position, air pressure and air masses, relief and ocean currents: there is low pressure at the equator and high pressure in the tropics, so equatorial, tropical and (at the edges) temperate air masses move over it. Humid winds from the Atlantic bring much rain to the Gulf of Guinea coast: the Debundscha area in Cameroon gets about 10 000 mm a year. Mountain slopes facing the humid wind get much rain. Cold currents passing near the coast (Canary, Benguela) cool the air and give no rain, which created coastal deserts such as the Namib. The highest reliable air temperature in Africa is considered about +55 °C (Tunisia, 1931); the +58 °C recorded at Al Aziziyah in Libya in 1922 was invalidated by the World Meteorological Organization in 2012 (the textbook still gives +58 °C). The highest mountains (Kilimanjaro, Mount Kenya) have permanent snow and ice.