Weather Words: Intertropical Convergence Zone

The Intertropical Convergence Zone, or ITCZ, is a belt that circles the Earth near the equator, where the trade winds from the Northern and Southern hemispheres meet.

This convergence forces warm, moist air upward, creating towering clouds and frequent thunderstorms. Because of this constant upward motion, the ITCZ is one of the planet’s most active regions for rainfall and is sometimes called the “rain belt” of the tropics.

The ITCZ isn’t a fixed line; it shifts north and south with the seasons. During the Northern Hemisphere’s summer, it moves slightly north, bringing heavy rains to regions like Central America, West Africa and Southeast Asia. In the winter, it shifts south, delivering monsoon rains to areas in the Southern Hemisphere.

This seasonal migration plays a major role in tropical climate patterns, including wet and dry seasons, and can even influence hurricane formation.

The seasonal shift of the ITCZ also influences when and where hurricanes can form. For example, during the Northern Hemisphere summer, the ITCZ moves north, creating favorable conditions for Atlantic and Caribbean hurricane formation.

Conversely, in the Southern Hemisphere, the ITCZ shifts south, affecting cyclone activity in the Indian and South Pacific oceans.

Without this convergence zone, many of the world’s strongest hurricanes and cyclones wouldn’t have the environment necessary to develop.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.