ITCZ) or equatorial trough. This line of convergence near the equator is also discernible in a map of streamlines (Figure 12.2; Note 12.A). It is actually a band a few hundred kilometres wide, enclosing places where winds flow inwards (are 'confluent') and subsequently rise convectively.he movement of the ITCZ across South Africa (Figure 12.1) is complicated by the land's shape, elevation and location, and there is a southerly spur called the Zaire Air Boundary (ZAB). Similarly, there is a spur over South America.