312 THE CLIMATE OF LOURENgO MARQUES. 



When I referred to the barometric disturbances I nien- 

 iioned the existence of the hot winds which are common to the 

 South African littoral. Alost of the distinguished Meteorolo- 

 gists who have studied these winds consider them absolutely 

 similar to the Foehn of the Alps, which was ably accounted for 

 by Dr. Hann, and is a very warm, dry wind, which blows in the 

 North of the xA.lps when a cyclone occurs in Western Europe, 

 with the lowest pressure in England and the lightest in the Eas- 

 tern Mediterranean, and in the south of the Alps in Italy, when 

 the reverse is the case. 



If we take Lourenco Marques only into account, a similar 

 explanation might at first sight appear as not being verv apposite 

 in view of the distance from the high mountains towards X and 

 NNW, and the fact, besides, that the elevation of the littoral to 

 the Rhodesia plateau is not abru})t. 



Originating, however, in Equaiorial Africa, it is natural that 

 its temperature should be high, and the descent towartls the 

 littoral makes it even warmer and drier, as in its passage to- 

 wards the south it does not travel through any region that could 

 decrease its temperature or increase its humiditw 



Absolute analogy with tlie winds of the South African coast 

 serves to justify this explanation, and this is also backed by the 

 fact that in Inhambane it is not so characteristically hot atul dry. 

 The wind there does not come, however, from high plateaus in 

 the interior. 



In opposition to this hot wind we have the south wind, the 

 low temperature of which has a greater influence on the climate 

 owing to its greater frequency than the NNW. which, as I said 

 before, lasts only a few hours and is seldom felt; it should not, 

 however, be mistaken in the percentage diagrams for the NNW 

 caused by the land-breeze. 



1 shall again call attention to the violent winds, with a 

 velocity corresponding to 60, 70, So, and 100 kilometres per 

 hour, which are felt at times when the south wind commences to 

 rise during an atmospheric perturbation. 



The "highest hourly velocities registered during the observa- 

 tions of 4 years were: 88 kilometres with SSE wind and yy 

 kilometres with south wind in October and Alarch, 191 1, veloci- 

 ties varying from 60 to 70 kilometres being often recorded. 



At Lourenco A barques no daily backing or veering of the 

 wind is noted. 



Relative Humtoitv and Vapour Tension. 



.Vccording to the widest classification a climate, the relative 

 humidity of wdiich falls between 66 % and 80 ^/c, is considered 

 as moderately moist, and this classification should apply to 

 Lourenco ]\Iarques, where, according to Table No. XI, not only 

 the annual l)Ut the monthly means are comprised within these 

 limits. 



