What Causes the Intertropical Convergence Zone?

The meeting of the northwest trade winds with the southwest trade winds causes a band of low pressure along the equator, which is known as the Intertropical convergence zone. In this area, solar heating causes the air to rise, leading to precipitation.

While the ITCZ remains near the equator, it also moves due to seasonal heating of landmasses. Although the typical definition of the ITCZ places it at a location from 5 degrees north or south of the equator, in some locations, it varies as much as 40 degrees. This movement of the ITCZ causes affects the weather pattern in the locations it covers.

While the ITCZ has some influence on continental weather, its greatest influence is over the oceans. Because it is where the trade winds meet and trade winds only occur over the ocean, the ITCZ only affects the weather patterns over the ocean. Other factors take greater precedence in determining the weather features over the large masses of land that form continents.

Weather stations in the ITCZ record the area as wet much of the year. Most locations show rainfall at least 200 days of the year. The areas are the wettest regions on the planet and are constantly hot and humid.

Although the convergence zone has vertical air movement, it has little horizontal movement. When ships were dependent on horizontal air movement and sails to move through the ocean, sailors named the region the doldrums.