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 the Intertropical Convergence Zone, 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 sail-powered boats for periods of days or weeks. The term appears to have arisen in the 18th century, when cross-equator sailing voyages became more common. Since this zone is the meeting place of two trade winds, it is also called intertropical convergence zone.