Marine Glossary

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Intertropical Convergence Zone (ITCZ)

The formal name of the doldrums. A discontinuous belt through the middle of the tropics which alternates between surface calms and extensive thunderstorms. It is the place where the northeasterly trade winds of the Northern Hemisphere meet (converge with) the southeasterly trade winds of the Southern Hemisphere. The zone lies within the equatorial air mass, near but usually not on the equator, but rather north of it. Its location and width varies daily and seasonally, generally forming over the warmest water in the region. The average width of the zone is some 150 miles.

See G216 for a sketch, or the World Atlas for more details.

Weather fax maps of the tropics (often called "tropical maps") show the boundaries of the zone (marked ITCZ) along with sketched clouds to show the regions of thunderstorms. High seas voice broadcasts (Source Book) give the coordinates of its boundaries. See example under weather report.

See World Atlas under Global Winds for a pictorial presentation and more details on its climatic locations. See G191 for a diagram of tropical cyclone formation within the ITCZ.

See also South Pacific Convergence Zone (SPCZ).

Abbreviation: ITCZ