A New Approach Towards Classification of Climates

Abstract

The basic requirements from a general stand point, for a rational system of classification of climates, have been enumerated with particular reference to the study of the arid zones. Some of the limitations of thornthwaite's "moisture index", based on potential evapotranspiration, have been pointed out. The significance of the diurnal range of temperatures as a composite climatic factor has been stressed, and a strong negative correlation between the annual average of diurnal temperature range and the average annual precipitation has been established for 150 noncoastal stations in India and neighborhood. A new climatic index has been defined in terms of the logarithm of the ration of these two variables, to enable classification of climates on a linear scale. A tomogram has been worked out for quick evaluation of this new climatic index, thereby avoiding the necessity of tedious computational work. A climatic map has been prepared from the data of 182 stations in India and neighborhood including 32 coastal stations. The map clearly bring out the rapid increase in aridity from western Rajasthan, across west Pakistan, towards further west.