CLIMATE. 23 



than that of heat in determining- the characteristics of the principal 

 seasons of the year. Its distribution is largely controlled by the 

 direction of the prevailing winds. In winter strong northwest winds, 

 blowing from the Mediterranean, are of frequent occurrence and bring 

 most of the rainstorms. They begin in the autumn, sometimes as 

 early as the first of September, and usually cease in May or June. 

 Even in midwinter, however, a clear sky for fifteen or thirty days at 

 a time is not a rare event. During the summer there is a light sea 

 breeze during the day, but winds of greater violence come almost 

 wholly from the south, and are dry and hot. 



More rain falls annually on the coast of Algeria, especially on the 

 eastern coast l)etween Algiers and Tunis, than in a great part of 

 Europe. Notwithstanding this, Algeria has a decidedly more arid 

 sunmier than any part of Europe, except, perhaps, extreme southern 

 Italy and portions of Spain. This is due to the uneciual distrilnition 

 of the rain among the different seasons. 



In the littoral zone winter is a wet rather than a cold season. It is 

 then that most of the native vegetation, as well as crops that are not 

 irrigated, must make their growth. The dry season is a period of 

 rest for soils that are not artiticially watered. Light showers of brief 

 duration, such as occasionally fall during the summer, are of small 

 importance in their effect upon the climate and vegetation. In the 

 large inland valleys of the coast region the summer drought is still 

 more pronounced than on the coast. 



In the mountain zone, particularly at the higher elevations, rain is 

 more evenly distributed, and the seasons are more like those of middle 

 Europe. The rainfall in March and April is particularly heavy. In 

 Great Kabylia thunderstorms and hail, which in the littoral zone 

 occur only in winter, are not infrequent throughout the summer. 

 This, with the partial protection from the sirocco afforded by the 

 higher ranges, makes the summer drought less pronounced than in the 

 littoral zone and in the valley and plain zone. But the total amount 

 of precipitation in sununer is, after all, comparatively insignificant. 

 Even in the mountains, sunmier retains its characteristics as the dry 

 season of the year. In winter the rainfall is quite considerable. The 

 northern slopes of the Djurdjura range receive the heaviest precipita- 

 tion occurring in the countrv— over 40 inches a year. These high 

 mountains form a barrier which intercepts most of the cloud-laden 

 winds from the sea, so that the country immediately to the south of 

 them is extremely arid. 



Rainfall is very unevenly distributed in different parts of the coast 

 region and even of the littoral zone proper. One reason for this is 

 the great difference in latitude— about two degrees— between the east- 

 enmiost and the westernmost point of the Algerian coast. Whil<> tiie 

 total annual precipitation on the coast near the Tunisian border 



