CLIMATE. 241 



volcanoes. It is easy to imagine circumstances when 

 reliable conclusions may be drawn from these indications 

 concerning- the direction of the winds in the several 

 superimposed strata of air. As the area of the centre 

 of cold over the ice-clad sea may be expected to be 

 enlarged during the winter, it may follow that the 

 anticyclone may also extend radially over the surface 

 of the sea. This conjecture receives support from the 

 fact that in Drake Strait frequent east and south-east 

 winds have been observed in the southern winter, which 

 are almost entirely absent in the southern summer. And 

 finally it is just this general distribution of south and 

 south-east winds which lends support to the assumption 

 that the south polar regions consist principally of masses 

 of land, as these alone are able to give birth to constant 

 anticyclones. 



Finally the last of the climatic elements, Precipitation, 

 seems to present great peculiarities, which it would be 

 specially interesting to observe in the summer months. 

 Arguing from analogy with the Arctic regions we infer 

 that in the Antarctic when the whole ice-clad surface, 

 land as well as water, consists of a uniform heat-radiating 

 area, a dryness of the atmosphere must prevail such as 

 accompanies every anticyclone, and this must be extreme 

 here, in consequence of the very low state of the 

 thermometer. This dryness, however, finds expression 

 in the absolute moisture of the air ; whilst, on the con- 

 trary, the relative moisture would have to be very high. 

 Over the inland ice of Greenland, Nansen found a 

 relative moisture averaging 94 per cent., but an absolute 

 moisture of only 2 mm. ( = *oo8 inch) of vapour-tension, 

 and a similar condition may assuredly be assumed to 

 exist in the Antarctic regions. The very scanty absolute 

 moisture is due to the exceedingly low temperature, the 

 large relative moisture to the surface of the ground 



being covered with snow, which even at low temperature 



16 



