MEINARDUS'S THEORY. 



253 



and 4,000 metres for January, July and the year at the difierent latitudes. The last line 

 contains the difference of the factors between 60° S. and the Pole. 



The conclusions to be drawn from this table are in Meinardus's ow^l words * : — 



' The table shows the following : The Antarctic anticyclone under the assumptions made 

 is no longer present at 2,000 metres in the winter and on the average of the 

 year, it has clearly given place to the Polar cyclone at this level. In January 

 on the other hand there is still a slight increase of pressure towards the Pole 

 at the 2,000 metre level, but even in this month there iS a small decrease at the 

 4,000 metre level. In other words the anticyclone in January reaches up to about 

 3,000 metres or a little higher, above this the surfaces of equal pressure are nearly 

 horizontal. The conditions deduced for January probably hold for December also ; 

 in November and February the gradient will be similar in sign to that for the 

 winter because the temperature of these months is considerably lower than that for 

 December and January.' 

 The calculations have been based on the assumption amongst others that the anti- 

 cyclone is as fully developed in January as in July. In view of the yearly varia- 

 tion of wind strength this is hardly likely. If the January pressure is decreased 

 relatively to the July pressure the anticyclonic gradient in 2,000 metres is naturally 

 decreased also, and it is possible that it might then even disappear at this height, 

 in other words the anticyclone might not reach 2,000 metres even in January. 

 In spite of the uncertainty of the main assumptions, the important result may be 

 accepted that the anticyclone is a phenomenon of the lower atmosphere in all 

 months and only in the summer rises above the 2,000 metre layer.' 

 Meinardus then refers to his calculation of the height of the Antarctic Continent f by 

 which he has shown that if one-third of the area ■ftdthin the Polar circle is at sea-level the 

 mean height of the remainder must be 2,000 metres. And the conclusion is dr-awn that the 

 surface of the high land within the Antarctic is above the anticyclone and therefore subjected 

 to cyclonic conditions. In this way he relegates the Antarctic anticyclone to a relatively 

 small fringe of the whole region within the Antarctic Circle, and gives the greater part of the 

 area over to the dominance of the Polar cyclone which he calculates exists above 2,000 

 metres. 



The consequence of Meinardus's reasoning is most clearly shown by a series of three 

 diagrams which he pubUshed in the April 1914 number of the Washington Monthly Weather 

 Review and which are reproduced here. 



The diagram reproduced as figure 75 represents ' Diagrammatic cross section of the south 

 Polar regions to show the position of the isobaric siurfaces and directions of the winds. 



Fig. 75. Meinardus's diagram of Antarctic pressure, vertical. 



* Loc. cit., page 331. 



t See page 294 below. 



