Green Shoots: 365 Days of Climate Awareness 229 – Overview of the African Climate

Much of Africa sits in the Intertropical Zone, the roughly 47° of latitude between the northern Tropic of Capricorn and the southern Tropic of Cancer. The continent is warm overall, with only a few temperate zones at higher elevations. There is greater range annually in precipitation than in temperatures, and this has more to do with the shape of the land mass and wind patterns. The northern and southern coasts have pleasant Mediterranean climates, but between them are tropical zones of both arid and rainforest type.

Köppen-Geiger climate diagram of Africa.

Annual rainfall in Africa.

The Sahara Desert (named directly from the feminine Arabic term for desert) covers 9.2 million km²/3.6 million mi² (13 times the size of Texas!), nearly 31% of the entire continent. It stretches from east to west across the entire northern portion of Africa, with only a few tiny oases and a narrow band of temperate coastline. The Sahara’s albedo is 32% and helps create the intensely stratified atmosphere which prevents vertical circulation and keeps the region virtually rain-free. Meanwhile, farther south, even as insolation increases approaching the equator, the rain forest, with an albedo as low as 9%, retains heat and moisture retention which reinforces the intensely rainy climate. Further south still, the climate becomes arid again over the bottom quarter of the continent.

Satellite image showing Africa's major climatic zones.

A glance at global wind cell circulation shows another aspect to Africa’s climate pattern. Converging, moist winds across the lower tropics tend to be loaded with moisture and produce the intense rains of that region. Farther to north and south, where the Hadley cells reach their poleward limits, dry, cool air descends back to earth, corresponding closely to the arid latitudes in the northern and southern areas of the continent. The elevations of the East Africa Mountains and the Atlas Mountains of Morocco do feature snow and 15-20 glaciers, though the glaciers are generally melting away.