254 



GENERAL AIR CIRCULATION. 



Arrows show the meridiaual components of the wind, shaded areas show the region of the 

 prevailing easterlies. Altitudes in metres.' 



This diagram is based on the values of the pressure at different heights given in table 

 131 above. The conditions which would hold if there were no land mass have been repre- 

 sented diagrammatically, and the outline of the continent superposed without altering the 

 position of the isobaric surfaces, the isobaric surfaces eliminated by the land mass being 

 shown by dotted Unes. 



This diagram shows clearly how according to the theory the greater part of the land 

 surface is subjected to cyclonic air motion. The air streams in from all sides and therefore is 

 compelled to rise over the land surface producing cloud and precipitation to supply the 

 water which flows northwards in the great ice streams. The edges of the land mass only 

 are subject to anticyclonic conditions with descending air currents. 



c09l ,„ 



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0-1 ^^' 



Fig. 76. Meinardus's diagram of Antai'Ctic pressure, sea-level. 



The next diagram, figure 76,* shows the sea-level isobars, it is explained in the original 

 as follows : — ' Sketch of the course of the isobars at sea-level within the south Polar regions. 

 The isobars are intentionally unnumbered except the curve for 740 mm. whose position can 



* Figures 76 aad 77 have been inverted in order that they may be easily compared with other diagrams 

 in this volume, in which the Rosa Sea area is always shown above the South Pole. 



