Asymmetry of the Intertropical Convergence Zone Asymmetry of the Intertropical Convergence Zone There are a number of explanations of the asymmetry of the Intertropical Convergence Zone (ITCZ), known by sailors as The Doldrums. The ITCZ would be expected to overlie the geographic equator according to symmetric solar radiation. However, the ITCZ is mostly perennial in the northern hemisphere and in the eastern Pacific and Atlantic Oceans. It was originally explained by the asymmetrical distribution of continents. However, the distribution of land and ocean is severely asymmetric in the Indian Ocean, yet the ITCZ moves back and forth there between the southern and northern hemispheres. Continents surround
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.