Equatorial trough

From Glossary of Meteorology



equatorial trough

  1. The quasi-continuous belt of low pressure lying between the subtropical high pressure belts of the Northern and Southern Hemispheres.

    This entire region is one of very homogeneous air, probably the most ideally barotropic region of the atmosphere. Yet humidity is so high that slight variations in stability cause major variations in weather. The position of the equatorial trough is fairly constant in the eastern portions of the Atlantic and Pacific, but it varies greatly with season in the western portions of those oceans and in southern Asia and the Indian Ocean. It moves into or toward the summer hemisphere. It has been suggested that this name be adopted as the one general term for this region of the atmosphere. Thus, the equatorial trough would be said to contain regions of doldrums; portions of it could be described as intertropical convergence zones; and within it there might be detected intertropical fronts. However, one weakness of this nomenclature is that it alludes specifically and only to the existence of a trough of low pressure. Perhaps an even more general term might be preferable, for example, atmospheric equator.

  2. Riehl, H. 1954. Tropical Meteorology. p. 238.

    Berry, F. A., E. Bollay and N. R. Beers, Eds. 1945. Handbook of Meteorology. 776–777.


Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.