Doldrums Doldrums The doldrums is a colloquial expression derived from historical maritime usage, which refers to those parts of the Atlantic Ocean and the Pacific Ocean affected by a low-pressure area around the equator where the prevailing winds are calm. The doldrums are also noted for calm periods when the winds disappear altogether, trapping sailing ships for periods of days or weeks. The term appears to have arisen in the eighteenth century, when trans-equator sailing voyages became more common. Since this zone is where two trade winds meet, it is also called the Intertropical Convergence Zone. They roughly lie between latitudes
Tropical wave waves. All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeastern Pacific basins. A tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data. A tropical wave normally follows an area of sinking, intensely dry air, blowing from the northeast. After