noun, Pathology. 1. the accumulation of excessive ketones in the body, as in diabetic acidosis. Origin of ketosis. 1915-1920.
Climate zones of Africa, showing the ecological break between the hot desert climate of the Sahara Desert (red), the hot semi-arid climate of the Sahel (orange) and the tropical climate of Central and Western Africa (blue).
Africa has a proportionately larger area in arid, or desert, climate zones than any continent except Australia. Each of these areas-the Sahara in the north, the Horn in the east, and the Kalahari and Namib deserts in the southwest-has less than 250 mm (less than 10 in) of rainfall annually.way from the equator, to the north and south, the savanna climate zone grades into the drier steppe climate zone. Average annual rainfall varies between 250 and 500 mm (10 and 20 in) and is concentrated in one season.