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,
Winds in the Age of Sail He took the southeast trade winds directly northwest across the South Atlantic to the Cape Verde Islands, the Azores, and home. Not only did Da Gama find a sea route to India, he discovered the most efficient sailing route there and back. In 1500 Pedro Álvares Cabral sailed somewhat west of Da Gama's route and bumped onto the coast of Brazil. Portuguese and Dutch in the Indian Ocean: After a few more voyages the Portuguese learned two things: that there was little market for European goods in the east, and the large Portuguese ships could outfight nearly any local craft.