COMPARISON OF THEORY WITH OBSERVATIONS. 



233 



. The remaining two lines show how the winds at Framheim vary during blizzards and 

 northerly winds at Cape Evans. The relationship comes out more clearly if we group the 

 Framheim winds as in the following table :— 



Table 127. 



Winds at FramJieim. 



During bhzzards N.E. to S.E. mnds at Framheim are nearly five times as frequent as 

 S. to S.W. winds, while during northerly winds at Cape Evans the S. to S.W. are actual 

 more frequent than the N.E. to S.E. winds. 



The relationship comes out still more clearly by taking the resultant direction and velocity 

 of the winds at Framheim during blizzards and northerly winds at Cape Evans. From table 

 127 we see that during blizzards the resultant wind at Framheim is nearly due east, while 

 during northerly winds it is from slightly to the west of south. Also the resultant velocity 

 at Framheim is nearly three times as great during blizzards as during northerly winds. Thus 

 the theoretical winds and the actual winds are in excellent agreement. 



We have now to examine the maps showing the isobars based on the actual observations 

 to see if they agree with the theoretical diagrams which we have constructed. 



A rapid glance through the maps is sufficient to show that the two main types of which 

 figures 71 and 66 are representatives are constantly repeated, while the great majority of the 

 maps vary only in detail from one or other of the theoretical diagrams. 



It would be too tedious to describe in detail many of the maps and to point out where 

 they agree and where they differ from the theoretical diagrams. The reader will be able 

 to see these points for himself if he is sufficiently interested to spend some time in com- 

 paring together the maps, plates and diagrams. 



It will therefore be sufficient if one or two typical examples are shortly discussed here 

 to indicate what should be looked for in a further study of the data. 



The first plate contains a very typical example of the effect of a moving pressure wave 

 on the pressure distribution. The actual pressure wave between the 6th and 10th was not 

 very large, but it produced a normal difference wave (bottom curve). 



The two maps for April 6th are similar to the two figures 66 and 67 which represent 

 the crest of a wave at Cape Adare with the difference wave decreasing. 



During April 7th the pressure distribution was changing and the two maps on this day 

 are similar to figures 68 and 69. The evening map shows that the easterly wind has started 

 near to Framheim, but it has not yet reached Cape Evans. 



At midnight on the 7th the blizzard started at Cape Evans and the maps for April 

 8th are similar to the theoretical diagrams for the bfizzard, figures 71 and 72. 



The map for 8 a.m. on the 9th is similar to figure 73 with the high pressure to the 

 south of Cape Evans. In the next map, 8 p.m. on the same day, the high pressure is shown 

 to have passed Cape Evans and the distribution is now becoming similar to that with which 

 we started, figure 66. The map for 8 a.m. on April 10th is almost exactly the same as 

 figures 67 and 68. 



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