South Atlantic High is a semipermanent pressure high centered at about 25°S, 15°W, in the Atlantic Ocean. It is also called the St. Helena High, Saint Helena island being the only land in the area. It can stretch thousands of miles across the South Atlantic.[1][2] This does not mean that the position and the intensity of this anticyclone are permanent, but just that there is an anticyclone on the maps describing the average monthly pressure. This area of high pressure is part of the great subtropical belt of anticyclones called the subtropical ridge. The centre of the high pressure region tends to follow the seasonal variation in position of the sun, moving south in the southern summer and north in the southern winter. This affects the climate of the adjacent continental areas, bringing seasonal changes to the climate and weather as the position of the high oscillates.
circulation de Hadley.