Related Resources • Climate & Weather • Trade Winds & Horse Latitudes • Equator & Tropics

by Matt T. Rosenberg

Near the equator, from about 5° north and 5° south, the northeast trade winds and southeast trade winds converge in a low pressure zone known as the Intertropical Convergence Zone or ITCZ. Solar heating in the region forces air to rise through convection which results in a plethora of precipitation. The ITCZ is a key component of the global circulation system.

Weather stations in the equatorial region experience precipitation up to 200 days each year, making the equatorial and ITC zones the wettest on the planet. The equatorial region lacks a dry season and is constantly hot and humid. Click here for an animated map of annual precipitation on the earth - pay close attention to the annual migration of the ITCZ region.

The location of the ITCZ varies throughout the year and while it remains near the equator, the ITCZ over land ventures farther north or south than the ITCZ over the oceans due to the variation in land temperatures. The location of the ITCZ can vary as much as 40° to 45° of latitude north or south of the equator based on the pattern of land and ocean.

In Africa, the ITCZ is located just south of the Sahel at about 10°, dumping rain on the region to the south of the desert. A current map of the ITCZ in Africa can be found online.

The Intertropical Convergence Zone has been called the doldrums by sailors due to the lack of horizontal air movement (the air simply rises with convection). The ITCZ is also known as the Equatorial Convergence Zone or Intertropical Front.

There's a diurnal cycle to the precipitation in the ITCZ. Clouds form in the late morning and early afternoon hours and then by 3 to 4 p.m., the hottest time of the day, convectional thunderstorms form and precipitation begins. Click here for an image of the Pacific Ocean with ITCZ storms clearly visible.