Astrophysics (Index)About

intertropical convergence zone

(ITCZ, doldrums)
(circulation pattern near equator where north and south Hadley cells meet)

The intertropical convergence zone (ITCZ) is the region of the atmosphere near the equator where the northern and southern Hadley cells, and their respective trade winds meet. Air is rising from warmth, drawing moisture upward, and leaving pressure low at the surface. The weather is erratic, including clouds, thunderstorms, and calm regions, the latter of which gave it its traditional maritime name, the doldrums. It shifts north of the equator during northern summer and south of the equator in southern summer. During these seasons the zone can move into monsoon regions i.e., regions that have sea breezes much like day/night sea breezes, but on a yearly cycle. The portion of the ITCZ in such a position is called a monsoon trough, and the ITCZ storms are amplified, resulting in the rainy season associated with monsoons.

The concept of the ITCZ applies to other worlds that have Hadley cells, thus are of interest in atmospheric models for them. This includes some solar system planets and moons (e.g., Titan) as well as some extra-solar planets.

Further reading: