CLIMATE OF ALGERIA. 



A consideration of the evaporation statistics of Algeria for the year 1908 

 shows some interesting relations. It has already been observed that the 

 rainfall along the coast is less in the west than in the east, and it will ap- 

 pear below that as a rule the temperature of the western portion is lower 

 than that of the corresponding regions lying to the east. In both rainfall 

 and temperature, however, the greatest variation is to be found as one 

 goes inland, when decreasing rainfall and higher temperatures are encoun- 

 tered. A similar relation obtains in evaporation, which becomes continu- 

 ously greater as the distance from the coast increases; that is, the average 

 evaporation for stations on the High Plateau is greater than for stations 

 in the Tell, and the evaporation at desert stations is greater than the evapo- 

 ration on the High Plateau. The total average evaporation for the year, 

 in millimeters, for 5 stations on the littoral, was 1,365.3; for 7 stations in 

 the Tell it was 1,378.6; for 4 stations on the High Plateau 2,352.2, and for 

 3 stations in the desert, 3,977.5. The least evaporation reported was 

 at Bouzarea, which was 989.9 mm., and the greatest was at Ghardaia, 

 5,309.7 mm.* 



Table 5 gives in detail the monthly as well as the total evaporation for 

 the year at three desert stations and at Algiers for 1908. 



Table 5. — Evaporation in millimeters, 1908. 



For a better personal appreciation of the rate of evaporation, as well as 

 for the purpose of comparison, I arranged an apparatus to tell the water- 

 loss from a free water-surface. It was also desirable to determine the 

 relative evaporation of the day and night. As employed, the apparatus 

 consisted of a flat tin dish, with parallel sides, 10 cm. in diameter. To the 

 side was attached, by means of a rubber stopper, a bent glass tube of small 

 diameter. The water-loss was read on this tube. Observations were made 

 at Laghouat and at Ghardaia. Following is a summary of the results obtained 

 at Ghardaia: For a period of 7 days, after November 10, the daily water- 

 loss between 7 a.m. and 7 p.m. was as follows: 5, 8, 8.5, 10.5, 13, 9, and 7.5 

 mm. The evaporation between 7 p.m. and 7 a.m. was so slight, 1 mm. 

 more or less, that it could not be well determined by the apparatus used. 



A good idea of the intensely arid character of the Algerian climate, taken 

 as a whole, is to be obtained by a study of the relation between the total 



* Unless otherwise stated, the climatological statistics given in this paper were taken 

 or compiled from Observations M6t6orologiques du Riseau Africain, 1907-1908. The 

 evaporation data are based on readings of the Piche evaporimeter. The amount of 

 evaporation given in the text can be reduced to the evaporation from a free-water 

 surface by multiplying by 0.737 (Meteorological Notes, J. I. Craig. Cairo Scientific 

 Journal, vol. vi, May 191 2). 



