THE 



SOUTH AFRICAN JOURNAL 

 OF SCIENCE, 



COMPRISING THE REPORT OF THE 



SOUTH AFRICAN ASSOCIATION A>^^os >,^.. 



FOR THE 



ADVANCEMENT OF SCIENCE. 



(1919, KINGWILLIAMSTOWN.) 





^■z.^'^- 



K^ 



* 



Vol. XVI. JAN MARCH, 1920- No. 4. 



SOUTH AFRICAN METEOROLOGY : TYPES OF ATMO- 

 SPHERIC PRESSURE, THEIR DURATION AND 

 MOVEMENTS. 



By a. G. Howard, M.S.A. Lond. 

 With Text Figures. 



Read July lo, 1919. 



The main atmospheric pressure condition affecting the 

 weather of South Africa is the anticyclone, which encircles the 

 earth between the tropical and temperate zones; this belt is at 

 its maximum over the oceans and at its minimum over the 

 continents. That portion over the South Atlantic Ocean is 

 constantly fluctuating in intensity, increasing towards the west, 

 forming a high pressure there, which, moving eastwards, breaks 

 off and rolls past the south coast in summer and across the land 

 in winter. Between any two high pressures one would expect to 

 find a V-shaped low pressure area to the north, and an inverted 



