CLIMATOLOGY OF THE PERUVIAN ANDES 143 



ers turn to the sea routes and the carriers have an increased busi- 

 ness. But so far as I have been able to learn, dry years favor 

 only a few scattered individuals. 



To the traveler on the west coast it is a source of constant sur- 

 prise that the sky is so often overcast and the ports hidden by fog, 

 while on every hand there are clear evidences of extreme aridity. 

 Likewise it is often inquired why the sunsets there should be often 

 so superlatively beautiful during the winter months when the 

 coast is fog bound. "Why a desert when the air is so humid? Why 

 striking sunsets when so many of the days are marked by dull 

 skies? As we have seen in the first part of this chapter, the big 

 desert tracts lie east of the Coast Range, and there, excepting 

 slight summer cloudiness, cloudless skies are the rule. The des- 

 ert just back of the coast is in many parts of Peru only a narrow 

 fringe of dry marine terraces quite unlike the real desert in type 

 of weather and in resources. The fog bank overhanging it 

 forms over the Humboldt Current which lies off shore; it drifts 

 landward with the onshore wind ; it forms over the up welling cold 

 water between the current and the shore; it gathers on the sea- 

 ward slopes of the coastal hills as the inflowing air ascends them 

 in its journey eastward. Sometimes it lies on the surface of the 

 land and the water; more frequently it is some distance above 

 them. On many parts of the coast its characteristic position is 

 from 2,000 to 4,000 feet above sea level, descending at night nearly 

 or quite to the surface, ascending by day and sometimes all but 

 disappearing except as rain-clouds on the hills. 3 Upon the local 

 behavior of the fog bank depends in large measure the local cli- 

 mate. A general description of the coastal climate will have many 



1 According to Ward's observations the base of the cloud belt averages between 

 2,000 and 3,000 feet above sea level (Climatic Notes Made During a Voyage Around 

 South America, Journ. of School Geogr., Vol. 2, 1898). On the south Peruvian coast, 

 specifically at Mollendo, Middendorf found the cloud belt beginning about 1,000 feet 

 and extending upwards to elevations of 3,000 to 4,000 feet. At Lima the clouds descend 

 to lower levels (El Clima de Lima, Bol. Soc. Geogr. de Lima, Vol. 15, 1904). In 

 the third edition of his Siid- und Mittelamerika (Leipzig and Vienna, 1914) Sievers 

 says that at Lima in the winter the cloud on the coast does not exceed an elevation 

 of 450 m. (1,500 feet) while on the hills it lies at elevations between 300 and 700 m. 

 (1,000 and 2,300 feet). 



