120 FORESTRY IN BRITISH EAST INDIA. 



temperature is found, due to a greater length of day and a later 

 arrival of the monsoon rains than in tropical India ; this region 

 receives to some extent compensation by 4 or 5 months of cool 

 and even cold weather during winter, representing at that time 

 a climate which has been compared with a south ItaUan summer. 



The third type of climate is found in Assam and north-eastern 

 Bengal. Here humidity of the air reigns supreme, although there 

 is a distinct summer and winter ; in either case the extremes of 

 temperature are moderated by the effects of a relatively large 

 amount of moisture in the atmosphere, which produces fogs in 

 winter and interferes in summer with the full effect of the sun's 

 rays on the land. 



Finally, the Himalayan mountains present, according to the 

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

 and even Alpine cUmate 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 eleva- 

 tion, the result of a system of atmospheric changes, which are 

 comparatively simple. The main-springs of the Indian cHmates 

 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), while it falls as 

 much as 5 to 10 degrees on j)roceeding towards the sea on the east 

 and west, and about 10 degrees on proceeding to the foot of the 



