The Climates of the Argentine Retublic According to the New Thornthmaite Classification

Abstract

T MHE purpose of a climatic classification is to characterize climatic regions in terms of those principal elements, such as temperature and precipitation, which are the most decisive in the determination of the landscape of the earth's surface. Moreover, it attempts to develop the similarities which these great climatic units bear to each other and their relation to their principal causes; the effect of latitude and of atmospheric and oceanic circulation, in opposition to geographic accidents. Climatic classifications owe their origin to phytogeographic descriptions. The physiognomic descriptions of plant associations are related to the first descriptive maps of the distribution of temperature and rain, and in this connection we should cite the valuable contributions of De Candolle (1855), Grisebach (1866), Drude (1887), and Schimper (1898) that include the analysis of the diverse plant associations of the world with relation to the principal climatic elements which determine them. Wladimir Koppen, contemporary of the phytogeographers mentioned, was the first to attempt a rational classification of the major climatic groups, taking as a basis the phytogeographical manifestations which they determine and adopting a terminology and symbolism similar to those used by previous authors (Koppen, 1884 and 1900). In later works this author sought an appropriate formula for expressing the relative value of rain, since its absolute value is not considered representative of its action over the earth's surface. In these studies he recognized the importance of a knowledge of evaporation in distinguishing between humid and dry climates. Being unable to measure evaporation, he developed as his indices relations between precipitation and temperature, weighing both in such manner that the resulting indices would correspond to the boundaries between the actual vegetation types. Since then, many authors have concerned themselves with this problem, attempting to improve upon the primary concepts established by Koppen. Penck