Breezes along the Tanzanian east coast

Abstract

At the Tanzanian east coast the prevailing winds of the general circulation exhibit seasonal changes in direction in a kind of monsoonal system. The sea and land breezes, which are limited here to diurnal modifications of the general winds, therefore also vary with the seasons. During the northeast monsoon a sea breeze trend prevails most of the time, while in the southeast monsoon season the main trend is from the land. Only during the intermediate periods between the monsoons a diurnal reversal of sea and land breezes develops regularly. The effects of these winds, especially the sea breeze, on the physiological temperature conditions near the coast are of considerable importance. A decrease of the physiological temperature is produced by the advection of cool air, and a further reduction of thermal stress is provided by the improved air ventilation related to the higher wind velocities of the breezes. Since all impressions of physiological temperature are subjective, it is difficult to express these influences quantitatively. However, estimates indicate that the old adage that “the winter in the tropics occurs at night” is no longer valid at the Tanzanian coast when the physiological temperature is considered, because the seasonal differences are larger than the diurnal variations.