Page:Africa by Élisée Reclus, Volume 2.djvu/272

 hottest month, rising to 78°, thus showing an extreme deviation of not more than 24°.

The usual division of the year into four seasons is scarcely applicable to Algeria, which has really not more than two well-defined periods — moist and temperate from September to the end of May, hot and dry for the remaining three months of the year. The position of Algeria on a coast completely exposed to the sea breezes gives to the anemometric régime a paramount influence in the distribution of heat, moisture, and atmospheric pressure. Here the winds have free play from all quarters, even from the interior, where the Sahel uplands retard their progress without perceptibly modifying their direction. The sirocco, or hot wind from the south, is tempered by the vicinity of the sea, while

the cold breezes from the north acquire a certain degree of heat during their passage across the Mediterranean. Algeria lies beyond the zone of regular trade winds; but during the fine season light and pleasant land and sea breezes succeed cach other regularly along the coast, the former prevailing at night, the latter during the day.

Elsewhere, owing to the radiation, the changes of temperature from night to day are very considerable, the thermometer under the solar rays rising in some places to 166° F., and falling in the hottest nights to 68° or 69° F., a discrepancy of 98° within the twenty-four hours. The result is a great condensation of aqueous vapour, with abundant dews and frequent fogs during the night and early morning, especially along the maritime districts. The rainfall itself is more