Intertropical Convergence Zone it is sometimes referred to as a monsoon trough, a usage more common in Australia and parts of Asia. In the seamen's speech, the zone is referred to as the doldrums because of its erratic (monotonous) weather patterns with stagnant calms and violent thunderstorms. The ITCZ appears as a band of clouds, usually thunderstorms, that encircle the globe near the Equator. In the Northern Hemisphere, the trade winds move in a southwestward direction from the northeast, while in the Southern Hemisphere, they move northwestward from the southeast. When the ITCZ is positioned north or south of the Equator, these directions
Winds in the Age of Sail them where they wanted to go. During the age of sail winds and currents determined trade routes and therefore influenced European imperialism and modern political geography. For an outline to the main wind systems see Global wind patterns. Pilotage or cabotage, in one sense, is the art of sailing along the coast using known landmarks. Navigation, in one sense, is the art of sailing long distances out of sight of land. Although the Polynesians were able to sail the Pacific (with great difficulty) and people regularly sailed north and south across the Mediterranean, before the time of Columbus nearly all