Intertropical Convergence Zone Intertropical Convergence Zone The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums or the calms, is the area encircling Earth near the Equator, where the northeast and southeast trade winds converge. The ITCZ was originally identified from the 1920s to the 1940s as the "Intertropical Front" ("ITF"), but after the recognition in the 1940s and the 1950s of the significance of wind field convergence in tropical weather production, the term "ITCZ" was then applied. When it lies near the Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation,
Thermal equator of maximum temperatures surrounding the globe which migrates roughly between the Tropic of Cancer and the Tropic of Capricorn. This region is known as the Intertropical Convergence Zone where the Earth orbits the Sun. This zone is the result of trade winds from the northern and southern part of the hemisphere eventually joining together. Still another definition states that the thermal equator is the latitude at which insolation is identical throughout the year. This is not the same as the astronomical equator because the Earth reaches perihelion (the minimum distance from the Sun in its orbit) in early January and