Physical Geography of the Great Oceans 91 



In North America, from its configuration, the extent of 

 country traversed by this wind is not so great as in the old 

 continent, but still we have the well-known alkali deserts 

 on the west side of the Rocky mountains. In the southern 

 hemisphere we have an exactly similar phenomenon. The 

 interior of Australia, except on the windward side, occupied 

 by the colonies of Victoria, New South Wales, and Queensland, 

 is a waterless desert; in South Africa we have the Kalahari 

 desert; and in South America we have the rainless regions 

 of the Argentine Republic and the Atacama desert. Here we 

 have, then, a feature due to climate, which repeats itself in 

 corresponding localities in the Old World and in the NYw. 

 in the northern hemisphere and in the southern. 



But the trade winds produce not only dry places on the 

 land, they produce also comparatively dry places on the !*ea. 

 The areas of maximum density or salinity of the surface water 

 are shown in the maps for the different oceans, and it will be 

 seen that they are situated in localities corresponding with those 

 of the deserts on land. 



In concentrating the surface water in the regions over 



ii the trade wind blows, it produces a powerful mechanical 



means of propagating the heat, obtained by the water at the 



ice from the sun, downwards into the colder depths below. 



All the year round, the water exposed to the influence of the 



wind is being energetically evaporated, while the rainfall 



in the same region is quite insignificant. The temperature 



varies with the season. When the temperature 



omes specifically lighter, notwithstanding 



ttinn which is going on, and it has no tendency 



ive the surface. When the temperature is falling, tin- water 



conrrntratr.l at m-.irly the same rate, and the 



!! fall of temperature combine to render 



It thus a. .juin-s the power of 



;.;h the water of same trmpriaturr but tOM -.tltness 

 ing its hiL'her temperature in the colder 



<lnnn.ll .iii.l m .mnual Oft ill I 



t at greater dej 



to propagate th< ],,\\, t .l.iily and the Ic> 



