292 POLAR PROBLEMS 



60°, as Lockyer shows them. Furthermore, Meinardus reaHzes the 

 great difficulty of postulating a normal anticyclone over Antarctica, 

 for this kind of eddy is essentially accompanied by dry conditions. 

 We know that large glaciers are being given off all round the Antarctic 

 Continent. These presuppose a constant accretion of snow or ice in 

 the interior, to keep up the supply, or one would imagine that the 

 central plateau would long since have been denuded of its icy carapace. 

 Indeed so marked is the outflowing character of the winds that Hobbs 

 talks of the general circulation as constituting an Antarctic " broom. "^ 

 He considers that the anticyclone winds continually sweep large quanti- 

 ties of snow and ice from the center toward the periphery. 



It is not necessary in this article to criticize the various theories 

 set forth to explain the origin of the snow. Hobbs believes that the 

 cirrus clouds furnish much of the precipitation. Meinardus places a 

 cyclone over the anticyclone, giving the indraft and cooling which 

 would seem to be essential. 



Simpson shows that an inversion of the circulation is clearly 

 demonstrated (above 5000 feet) by the cloud movements over Ross 

 Island. He follows Meinardus as regards the method of precipita- 

 tion but raises the "snow-supplying cyclone" well above the plateau. 

 He thinks that the plateau itself is everywhere controlled by a shallow 

 surface anticyclone. There is therefore not very much difference, so 

 far, between the views of Meinardus, Simpson, and Hobbs. 



ANTARCTIC PRESSURE WAVES 



When the local variations in pressure in Antarctica are investi- 

 gated it is found that they are usually not accompanied by changes 

 of wind direction, as in lower latitudes. Thus the passage of a low- 

 pressure wave from west to east in southern Australia over a given 

 place is accompanied by a rather sharp wind shift from north to south 

 at that place. Simpson finds that a series of pressure waves moves 

 across the Ross Sea area, affecting first the southern plateau and 

 Framheim, then Ross Island, and lastly Cape Adare (see Fig. 7). 

 The mean length of such a wave is 150 hours, and the mean variation 

 amounts to 0.572 inches. These waves take twelve hours to pass 

 from the south pole plateau to Framheim (which indicates that their 

 velocity is about 40 miles per hour). The normal pressure conditions 

 near Ross Island consist of a more or less permanent low over the 

 warm Ross Sea and the permanent high over the continent. Owing 

 to the Ferrel effect the resulting winds are deflected to the west. They 

 are "pent in" by the funnel of the great western scarp and so rush 

 past Cape Evans as southerly winds. Simpson believes that the 



5 W. H. Hobbs: The Glacial Anticyclones: The Poles of the Atmospheric Circulation, Univ. of 

 Michigan Studies: Sci. Ser., Vol. 4, New York, 1926. 



