OCEANIC CONTROL, OVER CLIMATE 37 



and South Pacific Oceans, the winds .tend to 

 cause a cyclonic drift in the winter, while they 

 cause an anticyclonic drift in the summer. 

 Maps of the Oceanic circulation in the Indian 

 Ocean represent the waters as moving in the 

 same direction as the wind in an anticyclone, 

 namely, in the direction opposite to the hands 

 of a watch. Hence the summer conditions 

 prevail. This is largely due to external factors. 

 From 40 S. to 50 S. is the belt of the 

 " roaring forties " which is swept by the wild 

 westerly winds that drive the waters from 

 west to east across the Southern Ocean. The 

 South-western corner of Australia, South 

 Africa and South America, all act as groins 

 against which the water is piled up by this 

 drift. This heaped up water overflows, and 

 as it is running down a slope, it may flow 

 independently of the local winds and even in 

 opposition to them. This overflow, therefore, 

 takes place as true ocean currents. 



Thus in the Indian Ocean, the westerly drift 

 in the Southern Ocean causes a northward 

 current along the western coast of Australia. 

 As the water passes northward, it falls under 

 the influence of the north-east trade winds ; it 

 is blown out to sea, and finally drifts westward 

 across the Indian Ocean as the " Equatorial 

 Drift." When this water reaches the coast of 

 Africa it is again piled up ; and this piled up 

 water has to escape in currents. It cannot 

 cross the equator, because it is kept back by 



