PREVALENT WINDS OF VICTORIA LAND 2o 



There are perhaps at least three possible sources of snow supply to the Ross 

 Sea region of Antarctica. 



(1) Surface northerly to north-easterly or north-westerly winds sucked inland by 

 the difterential heating of the rocks of the Antarctic Hoi^st and the adjacent snow- 

 fields on the one hand as compared with the water of Ross Sea on the other. These 

 may possibly be local extensions southwards of large cyclonic disturbances having 

 their centres perhaps north of Ross Sea. 



(2) Local "endless belts" of air travelling seawards at night as a land breeze, and 

 returning as a high-level (sometimes as a low-level) sea breeze during the day. These 

 are illustrated on Fig. 5. 



(3) The great Antarctic high-level cylone overlying the permanent anticyclone. 

 Some have doubted the existence of this cyclone, but from the fact that whenever 

 there was an extra powerful eruption of Erebus, so that its steam cloud was carried 

 to an altitude of about 20,000 feet, we invariably noticed that it was caught by a 

 powerful W.N.W. or N.W. current, we are inclined to believe that this huge 

 permanent cyclone really exists. It is to this source that the eminent Austrian 

 meteorologist Dr. Julius Hann would refer most of the snow that falls far inland in 

 Antarctica, following in this respect the German meteorologist Meinardus, whose 

 fine memoir has shed so much light on atmospheric circulation in Antai'ctica. Hann 

 quotes Meinardus * to this general effect : 



" These considerations will also do away with the difficulty of explaining 

 the ice masses radiating away from the Antarctic Continent, for the centre of a 

 great fixed anticyclone is not only poor in snowfall, but is rather a place of increased 

 evaporation ; it is a region for starvation, not for alimentation of ice and glaciers. 



" But if cyclonic westerly winds extend into the higher altitudes of the Antarctic 

 Continent, provision is made for the conveyance of vapour and for precipitation. Thus 

 precipitation will not be wanting even in the interior of Antarctica." 



Professor Hobbs in his " Characteristics of Existing Glaciers " has followed Hann's 

 views. 



We know very little about snowfall on the inland ice of Antarctica during the 

 winter, but know something about the supply in summer. 



Snowfall. We may commence with the Magnetic Pole Plateau. As regards 

 source of snow supply to this plateau, it is obvious that the prevalent winds depend, 

 in part, for their direction upon the slope of the ground. The summit of the plateau 

 has been termed on the map " the parting of the winds," and possibly it has actually 

 in part been formed by the action of the winds. If the western winds 

 perform more erosive work than the south-eastern upon equal quantities of annual 

 snowfall, the divide will migrate westwards. If the reverse is the case, the divide 

 will migrate south-eastwards. There can be no doubt that the original fall of the 

 rocky plateau divided the position of the parting of movement of the inland snow and 



* "Handbuch der Klimatologie," von Prof. Dr. J. Hann. Vol. iii. p. 689. 



I) 



