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equatorial belt of calms,area around the earth centered slightly north of the equator between the two belts of trade winds. The large amount of solar radiation that arrives at the earth in this area causes intense heating of the land and ocean. This heating results in the rising of warm, moist air; low air pressure; cloudiness; high humidity; light, variable winds; and various forms of severe weather, such as thunderstorms and squalls. Hurricanes originate in this region. The doldrums are also noted for calms, periods when the winds disappear, trapping sailing vessels for days or weeks.
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A nautical term for the equatorial trough, with special reference to the light and variable nature of the winds. Also known as equatorial calms.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
Regions of calm, light variable winds and thunderstorms girdling the ocean near the equator and varying in extent and position according to the season. The doldrums lie between the northeasterly tradewinds of the Northern Hemisphere and the southwesterly tradewinds of the Southern Hemisphere, roughly between latitudes 10°N and 10°S. Air heated at the earth's surface rises in the doldrums region and flows northeastward and southwest-ward at heights from 0.8 to 6 km to form antitradewinds. The doldrums are low-pressure calm latitudes and the horse latitudes are high-pressure calm latitudes.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
a. a belt of light winds or calms along the equator
b. the weather conditions experienced in this belt, formerly a hazard to sailing vessels
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005