CLIMATE AND RAINFALL. 98 



Finally, the Himalayan mountains present, according to 

 the elevation and position of each locality, a more or less 

 temperate and even Alpine climate with frost, snow, sleet and 

 bitter winds in winter and a moderate heat in summer. 



Between these four types any number of intermediate 

 climates are found. However large their number may be, 

 and however much the various climates may differ, they are, 

 apart from elevation, the result of a system of atmospheric 

 changes, which are comparatively simple. The main-springs 

 of the Indian climates are the following : — 



(1.) In spring and summer the extensive plains and table 

 lands of India are heated to a much higher degree than the 

 surrounding sea ; during winter the air overlying the sea is 

 warmer than that over the land, from which at that season 

 of the year heat freely radiates. The results are sea breezes 

 during summer and land breezes during winter. 



(2.) The greater or smaller tendency with which moisture- 

 laden air presses during spring and summer from the south 

 towards India. 



(3.) The effect produced by the snowfall of the Himalayas 

 on the movement of dry air currents coming from the north- 

 west and penetrating into the Peninsula. 



It will be useful to enter somewhat into the details of these 

 phenomena. In spring, which shall here comprise the months 

 of March, April and May, the highest temperature is found 

 over the centre of the Peninsula (Nagpur, Hyderabad), wliile 

 it falls as much as 5 to 10 degrees in proceeding towards the 

 sea on the east and west, and about 10 degrees proceeding to 

 the foot of the Himalayas or to the Punjab i)lain. The effect 

 is that the air over the centre of the Peninsula expands, lifts 

 the higher layers of air, causes them to flow away on all sides 

 and produces a centre of comparatively low pressure. Into 

 this centre presses the heavier atmosphere from the sea, 

 causing the sea breezes so characteristic of the spring months. 



These air currents deviate, however, from their original 

 course in consequence of the law that everything moving on 



