THE SCIENCE OF THE WEATHER 



THE aim of modern meteorology is to investigate the great 

 ocean of air that surrounds our planet and to discover 

 the laws that govern its circulation. A complete know- 

 ledge of these laws would render possible the forecasting of the 

 weather for considerable periods, and thereby meteorology would 

 prove itself to be a science of the greatest value. 



Climatic conditions, more than anything else, limit the habit- 

 able area of the earth. Although there is probably no climate 

 to which man cannot adapt himself, the coldest lands are either 

 uninhabited, or sparsely populated like Northern Siberia for 

 example. The influence of climatic conditions on race tempera- 

 ment is very pronounced, and has often far-reaching conse- 

 quences. In the past history of the earth there have been great 

 changes in the climate brought about by a succession of ice-ages ; 

 periods when vast areas of Europe and North America lay hid- 

 den beneath great fields of ice, when the great mountain-systems 

 formed the cores of mighty glaciers, from which, after the ice- 

 ages had been succeeded by warmer periods, great rivers flowed 

 down and fed lakes and inland seas, where now there is nought 

 but the sand of the desert, or at most some shrunken lakes with 

 no outlet to the sea. All this occurred, however, ages ago, and 

 though at the present time the earth's surface shows conspicuous 

 belts of desert, there is no definite evidence of a general drying-up 

 having occurred within historic times ; in fact, in some places there 

 is not wanting proof to the contrary. Thus, in Central Asia 



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