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,
Tropical wave waves. All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeastern Pacific basins. A tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data. A tropical wave normally follows an area of sinking, intensely dry air, blowing from the northeast. After