Intertropical Convergence Zone

The Intertropical Convergence Zone (ITCZ) is the tropical belt of low pressure and converging trade winds where deep convection and heavy rainfall are commonly concentrated.

Why it matters

Its seasonal migration helps organize tropical rainfall patterns, cloudiness, and surface wind fields. Because the ITCZ shifts north and south through the year, it is a major control on tropical wet and dry seasons.

Physical picture

The ITCZ is not a single fixed line but a migrating convective zone shaped by solar heating, SST gradients, and large-scale circulation. Where the trade winds converge, air rises, cools, condenses, and supports persistent deep cloud development and rainfall.

In the Galapagos

For the Galapagos Islands, a more southward or nearby ITCZ position during the hot season favors deeper convection and stronger Precipitation. When the ITCZ is farther away and eastern Pacific waters are cooler, the archipelago is more strongly influenced by the stable low-cloud regime associated with Garua.

Relation to ENSO

Changes in tropical Pacific SST patterns during ENSO can shift the regional position and convective influence of the ITCZ. That is one reason ENSO alters rainfall seasonality and event intensity across the eastern equatorial Pacific.

See also: El Nino-Southern Oscillation, Precipitation, Walker circulation, Heavy rainfall in the Galapagos, Galapagos seasonality