Intertropical Convergence Zone of human errors which ultimately doomed the flight. Most aircraft flying these routes are able to avoid the larger convective cells without incident. 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
Tropical instability waves El Niño conditions are present. Tropical instability waves are not related to tropical waves, which are atmospheric disturbances that propagate westward along the Intertropical Convergence Zone, sometimes giving rise to tropical storms. In both the Atlantic and Pacific oceans, a tongue of cold surface water usually extends westward along the equator from the continental margins. These "cold tongues" consist of water upwelling from the ocean depths, and are surrounded by warmer surface water in both hemispheres. The temperature difference between the cold tongues and the surrounding warm water is largest during the southern hemisphere winter. The Pacific cold tongue is