Climate

Abstract

The very phrase, ‘tropical rain forest’, indicates that the existence of this type of vegetation is primarily conditioned by climate. The tropics are generally considered to be located between latitudes 23° N and 23° S, the ‘tropic of Cancer’ and the ‘tropic of Capricorn’ respectively. At the equator, the mean temperature at sea level is around 26°C, and the prevailing 12-h day length shows little seasonal variation. Though hot, the tropical region therefore never becomes excessively hot compared to desert regions at higher latitudes, where days become longer in summer time, and these high, but not too high, temperatures permit the existence of a true tropical rain forest. In other permanently wet areas with cooler temperatures, for example in New Zealand, a kind of rain forest exists, but not with all the characteristics typical of a tropical rain forest growing between the tropics. There is a close relationship between heat (plus moisture) and the typical structure of a tropical rain forest with its giant trees and buttresses.