CLIMATE OF ALGERIA. 



The seasonal percentages of precipitation give a more graphic concep- 

 tion of the rainfall conditions for the four physiographic provinces. In 

 the Tell this percentage in winter is 42, in spring 27, in summer 4, and in 

 autumn 27. On the High Plateau the percentages are 30, 20, 16, and 34 

 for the four seasons respectively. In the Saharan Atlas 30 per cent of the 

 rain occurs in winter, 24 in spring, 13 in summer, and 33 in autumn. In the 

 desert the percentages of rainfall are 37, 39, 4, and 20* for the four seasons. 



It is of interest also to note the number of days on which the rain fell 

 on an average each year over a period running from 7 to 12 years. Thus 

 at two typical stations on the Tell rain was reported on 102 and 118 days; 

 at two stations on the High Plateau it rained 65 and 83.8 days; at a station 

 in the Saharan Atlas rain was reported on 70 days; at desert stations, at 

 Ouargla rain fell on an average 14.2, and at Laghouat 49 days each year. 

 As a comparison, it may be mentioned that for ten years at Wady Halfi, 

 Egyptian Sudan, there were only 22 days on which rain-drops were seen 

 to fall. (Engler, loc. cit.) 



The amount of precipitation varies greatly for the different desert sta- 

 tions, usually becoming less as one goes south from the High Plateau. As 

 has already been mentioned, the average rainfall at Laghouat, which lies 

 at the southern base of the Saharan Atlas, is 198 mm., the average at 

 Ghardaia is 114 mm., while that at El Golea is 47 mm. The latter station 

 is about 225 miles south of Laghouat, in the midst of the Sahara. The 

 amount of rainfall, however, is greatly influenced by altitude, although 

 lack of adequate precipitation data for the desert makes impossible a 

 detailed presentation of this phase of the subject. As the amount of the 

 yearly precipitation is less in the extreme southern part of Algeria than it 

 is nearer the Saharan Atlas, where the altitude also is greater, it might be 

 expected that the number of rainy days would vary in a like manner. Such 

 records as are at hand, however, do not show this to be the case. For in- 

 stance, at Ouargla rain falls on an average 14.2 days, average of 7 years. 



* The seasonal distribution of rain (by percentages) 

 is somewhat different from that given by Engler, 

 which is given in the accompanying table. 



