CLIMATE. 243 



not required to produce these phenomena, at least not 

 with land of low elevation, whilst with Victoria Land, for 

 example, it would have to be still more considerable. 



The state of things must be different in the southern 

 summer, if not in principle, at least in effect, as the large 

 vapour-supplying water surfaces of the open basins of 

 Ross Sea and Weddell Sea, and possibly also other still 

 unknown bays or gulfs, make their influence felt in the 

 Antarctic regions. Over these regions the air, probably 

 still cold, but in comparison with winter much warmer, 

 may be abundantly charged with water-vapour, which is 

 carried partly perhaps to the coasts by sea-breezes, but 

 mainly to the interior in the manner above indicated. In 

 summer the relative moisture in the air over the Antarctic 

 waters is very great ; on 30 per cent, to 40 per cent, of 

 the days that Ross passed within 6o° S. it amounted to 

 100 per cent, in other words, the air was saturated with 

 moisture ; the number of days when the relative moisture 

 was 100 per cent, between 74 and yS° S. was small, 

 amounting only to 25*8 per cent, of the total number of 

 days. On the remaining days it hovered near the point 

 of saturation, whilst low numbers were observed only 

 twice, viz. : 62*5 per cent, in the neighbourhood of Mount 

 Erebus, accompanied by a rising temperature and a wind 

 coming from the land, consequently a kind of Fohn, and 

 52-6 per cent, at the edge of the pack-ice, accompanied 

 by an east wind proceeding from it. 



The precipitation in the southern summer corresponds 

 with the state of relative moisture prevailing over the sea. 

 As has already been observed, water-vapour rises inces- 

 santly from the sea, and if this moisture penetrates cold 

 air, it generates the fogs which are so frequent a pheno- 

 menon of the Antarctic waters ; and if, in addition, land 

 winds bring this air in contact with the much colder air 

 of their place of origin the fog is succeeded or accompanied 

 by snow. Wilkes expressly says, that the winds from 



