140 The Realm of Nature CHAP. 



most of India it is a dry season, as the air of the North- 

 East or Winter Monsoon has descended from the upper 

 region of the atmosphere, and contains little water-vapour. 

 On the east coast of the Indian peninsula and of Ceylon, 

 the north-east wind having traversed the Bay of Bengal, 

 sweeps along a considerable amount of vapour, which is 

 precipitated on the Eastern Ghats and the eastern side of 

 the Ceylon hills, winter being their rainy season. 



196. Winds of the Southern Hemisphere in July. 

 Notwithstanding the change from summer to winter in the 

 southern hemisphere, the southern region of low pressure is 

 practically unaltered in position, but the gradient southward 

 is reduced, and the winds of the Roaring Forties blow with 

 slightly diminished strength. The south tropical belt of high 

 pressure has reunited in consequence of the cooling down of 

 the southern continents, and it now stretches far north of the 

 tropic. In consequence of the small range of temperature 

 and slight winter cooling of the southern continents, the 

 highest pressure in the southern hemisphere is over the 

 oceans even in winter, and this fact accounts for the per- 

 manence and steadiness of the brave west winds. The 

 south-east trades blow across the equator far to the north 

 in all the oceans. In the Indian Ocean the calm belt is 

 completely obliterated on account of the great suction over 

 Asia which draws supplies from the southern hemisphere 

 and turns the south-east trade winds to feed the south-west 

 monsoon. At the same time pressure is high over the 

 continent of Australia, from which monsoon winds blow 

 outward. 



197- Winds of the Northern Hemisphere in July. 

 The equatorial belt of low pressure extends over the whole 

 land surface of the northern hemisphere and unites with 

 the North Polar region of low pressure, centres of lowest 

 pressure lying in the south-west of Asia and in the west of 

 North America. The north tropical belt of high pressure 

 is broken into two great isolated high-pressure areas, which 

 occupy the North Atlantic and the North -West Pacific, 

 keeping up the north-east trade winds in those oceans ; 

 and giving rise to south-westerly winds over eastern North- 



