260 J. W. BEWS. 



(2) RAINFALL AND MIST. 



Natal is a region of summer rainfall, 77 per cent, of the 

 average annual rainfall coming between October and March, 

 and only 23 per cent, between April and September. The 

 months of June and July are frequently rainless. The wet 

 summers and dry winters have a general injfluence on the 

 vegetation of Natal, and this factor deserves the fullest 

 attention when the end in view is a comparison of the plant 

 life of Natal, with that of outside areas, e.g. with the west 

 side of the Cape Province. 



1. The Local Variation in Eainfall. — To help to explain 

 the variation in the character of the vegetation within Natal 

 the following facts are of most importance : 



A. The higher ridges and hills receive a considerably 

 greater rainfall than the lower valley levels. All the main 

 river valleys are dry valleys. The rain clouds pass over 

 them without depositing much moisture. 



B. The forest areas being cooler receive a much greater 

 rainfall. When air which is almost saturated with moisture 

 strikes any cooler area the moisture is, of course, deposited. 

 The forests of Natal, as we shall see, occupy the places 

 where the rainfall for other reasons would be greatest 

 even if they were not covered with trees, but the fact that 

 they are forest areas increases the rainfall. 



c. The rain clouds are borne by the south-easterly winds 

 from the Indian Ocean. As soon as they strike the coast a 

 certain amount of moisture is deposited. Stations on the 

 coast, therefore, show a fairly high annual rainfall. The 

 rain here is also somewhat more uniformly distributed 

 throughout the year. It is not unusual to find that even 

 during the dry months of June and July there have been a 

 few wet days on the coast. At Port Durnf ord in Zululand, I 

 am informed by Mr. A. Hammar, Grovernment Surveyor, 

 that there are surprisingly heavy rains during winter. The 

 warm Mozambique current flows down along the East African 



