The Anti-Trade Winds

Abstract

FATHER SARASOLA'S observations are certainly out of harmony with the older ideas about the general circulation of the atmosphere as due to Ferrel, Dove, and others, but these are not nowadays accepted as anything more than a rough approximation, and the observations, in fact, lend most valuable local support to more recent views, according to which over the equatorial limits of the north-east and south-east trades the average direction of the wind is respectively south-east and north-east, becoming south-west and north-west respectively above the polar margins of the trades. A scheme involving this disposition of the anti-trades was, as I indicated in the article in NATURE of July 18, put forth by Blair (Monthly Weather Review, 1916), and various upper air observations in different localities certainly support it. In the vicinity of the Cape Verde Islands, lat 16° N., the “anti-trade” is, I believe, south-east, in conformity with the observations in Colombia, whereas in the vicinity of the Canary Islands in lat. 28° N. it becomes south-west. In a report of upper air observations at the Apia Observatory, Samoa (14° S.), during 1923–24, the anti- or counter-trade is very definitely established above the south-east trade, its base being between the altitudes of three to five miles according to season, the direction being north-east below and changing through north to north-west above.