Environmental Characteristics

Abstract

The climate of the Sahel is typically tropical with a monomodal precipitation pattern and rainfall occurring in a short summer season, i.e. during the long-day period. The rainy season follows the apparent course of the sun at the zenith; the rains are therefore sometimes called “zenithal rains”. The rains are provoked by the monsoon of the Gulf of Guinea and the northward movement of the Intertropical Convergence Zone (ITCZ) also called Intertropical Front (FIT, in French). The northward progress and southward retreat of the ITCZ roughly follow the apparent march of the sun at the zenith which is at the equator at the equinoxes, on the Tropic of Cancer at the June solstice and on the Tropic of Capricorn at the December solstice, (Figs. 6-7).