Equatorial westerlies

From Glossary of Meteorology

equatorial westerlies

The westerly winds occasionally found in the equatorial trough and separated from the midlatitude westerlies by the broad belt of easterly trade winds.

As the air flow in the lower atmosphere is mostly easterly in and about the equatorial trough, the existence of westerlies on mean charts in some areas has been a subject of much interest and speculation. In some regions, this abnormality can be explained as the result of limited areas of west winds on the equatorward side of frequent westward moving cyclones in the equatorial trough. Elsewhere (notably over the Indian Ocean during the Northern Hemisphere summer), the equatorial westerlies may result from the deflection of Southern Hemisphere air as it flows northward across the geographical equator as part of the monsoon. Equatorial westerlies can also be induced on the western side of a large scale localized heating near the equator, such as in the maritime continent.

Palmer, C. E. 1951. Compendium of Meteorology. p. 876.

Riehl, H. 1954. Tropical Meteorology. 3–4.

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.