ABSTRACT
A somewhat similar climate extends right across Africa as far as the headwaters of the Nile and it is from the summer rains that the White Nile gets some of its water. The rhythmic climate imposes a rigid rhythm on agricultural practice; water for growing plants is available, without irrigation, only in the rainy season, while the dry season is the time of harvest. The altitude and the bright light are stimulating, perhaps too stimulating after a time, and Europeans find the climate physiologically congenial as well as agriculturally productive. In North Africa the extent of the tropical climates is the extent of the swing of the equatorial rainfall belt, for the trade winds have come overland all the way and bring no rain; the margin of the desert is therefore sharply defined and runs almost due east and west.
