168 



THE ANDES OF SOUTHERN PERU 



the weather of high stations, or indeed of wind-phenomena in gen- 

 eral, is due, however, to exceptional changes in wind strength on 

 two days of the month, the 16th and 25th, when the velocity de- 

 creased from a little less than a thousand meters per minute in 

 the morning to 4 and 152 meters respectively in the afternoon. 

 More typical is the March record for 1914 at Santa Lucia, when 

 the wind was always stronger in the afternoon than in the morn- 

 ing, their ratios being 550 to 510. 



CLOUD 



The greater strength of the afternoon wind would lead us to 

 suppose that the cloudiness, which in the trade-wind belt, is to so 

 great an extent dependent on the wind, is greatest in the after- 

 noon. The diagrams bring out this fact. Earely is the sky quite 

 clear after the noon hour. Still more striking is the contrast be- 

 tween the morning and afternoon if we combine the two densest 

 shadings of the figures. Light, high-lying cirrus clouds are most 

 characteristic of early morning hours. They produce some very 

 striking sky effects just before sunrise as they catch the sun's rays 

 aloft. An hour or two after sunrise they disappear and small 

 cumulus clouds begin to form. These grow rapidly as the winds 

 begin and by afternoon become bulky and numerous. In the wet 

 season they grow into the nimbus and stratus types that precede 

 a sudden downpour of water or a furious hailstorm. This is best 

 seen from the base of a mountain range looking towards the crest, 

 where the cloud- and rain-making processes of this type are most 

 active. 





CLOUD 



ANALYSIS, SANTA LUCIA 











Type of cloud 



Nov. 

 a. m. p. m. 



Dec. 

 a. m. p. m. 



Jan. 



a. m. p. m. 



Feb. 

 a. m. p 



m. 



March 

 a. m. p. m. 



Total 

 a. m. p. m. 





6 



4 

 3 

 2 



2 



4 

 4 

 6 



15 2 



7 11 



4 7 



3 10 



— 1 



9 



9 2 



3 5 

 10 9 



7 14 



2 1 



5 



6 



15 



2 



3 



8 



13 



3 



1 



6 



17 

 5 



1 



2 



3 



10 



13 



3 



2 



41 12 









37 38 





37 46 





14 36 





2 4 







Clear 



6 1 



