Physical Features of Sub-Saharan Africa

Before we get started, take a moment to study the map in Figure 6.1. The red dashed line indicates the approximate "border" of the Sahel and the southern boundary of the African Transition Zone. The location of the Sahel is inexact because it shifts according to the seasons. This is why many call it the African Transition Zone, a name that accounts for its changing location.

This shifting zone is where the subtropical high-pressure belt that contributes to the arid conditions of the Sahara Desert meets the Intertropical Convergence Zone (ITCZ), an equatorial low-pressure zone that makes the tropics wet.

The African Transition Zone shifts due to the seasonal shifts of the ITCZ. It shifts north in the summer, making the conditions wetter, and shifts south In the winter, making the conditions drier. Variations to this pattern occur when the high- and low-pressure belts stall for various environmental reasons, leaving the Sahel with no moisture.