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).
Scarcity of Rainfall. Dryness rather than heat is what makes the Sahara a desert climate. Divergent air masses within the high-pressure system dry the air before fronts can form. Even the subtropical zones near the west see relatively low amounts of precipitation. The Sahara Desert averages under 3 inches of rainfall yearly.