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
Trade winds within the subtropical ridge. The weaker the trade winds become, the more rainfall can be expected in the neighboring landmasses. The term "trade winds" originally derives from the early fourteenth century late Middle English word "trade," meaning "path" or "track." The Portuguese recognized the importance of the trade winds (then the "Volta do mar", meaning in Portuguese "turn of the sea" but also "return from the sea") in navigation in both the north and south Atlantic ocean as early as the 15th century. From West Africa, the Portuguese had to sail away from continental Africa, that is, to west and