The Barometer in South Africa. 



89 



10 



30 





P/i55AGf0fA V-3///iP£D D£P/?£J3/0/V. 



The long arrow shows the path of the V. Its passage is marked by 

 strong N winds with a rapidly falling barometer ; the moment the 

 trough of the V, marked by the line going NNW-SSE passes, the 

 wind jumps to the south with a dust squall and lightning and rain 

 soon follow, temperature falls very low and the barometer rises. 

 Unfortunately for the Transvaal these Vs seldom bring rain in winter 

 time ; we have the dust-storm, perhaps a few flakes of snow, and a 

 otiff, cold gale from the S, which may last 48 hours. 



It will be noticed that rain comes with a low and falling or 

 nearly stationary barometer in a cyclone, but with a rising barometer 

 in a V. 



Thus the cyclonic rains of the Cape Peninsula in Winter show 

 an unusually low pressure, whilst the occasional rains there in 

 Summer show a pressure above the average. This is brought out 

 clearly by the figures in Table 2 of the Cape Barometer tables 

 in the 3rd section of this paper. 



Referring back to the diagram showing the barometer curves about 

 the period of the great storm at Durban, 31 May-i June, we see that it 

 shows all the characteristics of a V. For some days previous to the 

 storm, the barometer was low over South Africa ; this permitted the 

 formation of a dangert)us V, which, however, scarcely touched the 

 Cape (on the 29th May) ; by the time the V had entered Natal and 

 the Transvaal, pressure was rising rapidly at the Cape. The shading 

 on the curves indicates rain, which, as usual, came with a rising 

 barometer ; the rainfall at Durban was terrific, at Johannesburg a few 

 flakes of snow fell. 



Such are my first ideas on our weather sequences. Without 

 doubt, great modifications will be necessary. The theory of the 

 eastern cyclones is distasteful to my preconceived ideas, but I accept 

 it and other theories for the time being. 



