222 



Pressure, winds and weather. 



(a) 



Fig. 66. Modified pressure distribution <^=<15°, 



9 = 45°, figure 66. — Starting with the crest of the pressure wave at Cape Adare the 

 change of pressure due to the inii>ressed wave has been shown in the upper line of bold 

 figures. These values have been added to the lines of figures against each in the normal 

 diagram, figure 65a, with the resulting pressure over the whole area shown by the figures 

 in the squares. Isobars through these figures show the resulting pressure distribution. The 

 added pressure is sufficient to reverse the normal pressure distribution and the highest pressure 

 is near Cape Adare and the lowest over the Barriei to the south-east of Framheim. 



The simple addition of the pressure makes the isobars as shown on figure 66a start 

 on the Western Mountains and run to the north-north-east. The air motion would be in 

 this direction except that it obviously cannot flow awaj' from the mountains along their whole 

 length. The air motion near the mountains will be from high to low pressure but parallel 

 to the range, i.e., the wind will be from the north to the south near the mountains. Over 

 the Ross Sea at some distance from the mountains the air motion will be along the isobars, 

 i.e., from the south-west. These directions have been shown by arrows in figure 666 in which 

 the isobars have been changed to be in accordance with the air motion. This adjustment 

 of the isobars to the air motion lowers the pressure at Cape Evans by about '15", as 

 will be seen by comparing tht; isobars in the two halves of the diagram. The probable wind 

 strength has been shown by the number of feathers on the arrows, which, however, are only 

 qualitative as no calculation seems feasible. 



