CLIMATE OF THE SANTA CATALINA MOUNTAINS. 



55 



Smith* has deduced two curves of altitudinal increase of rain, one 

 applicable to Pima and Pinal Counties, Arizona (the counties in which 

 the Santa Catalinas lie), the second to Graham and Cochise Counties. 

 These curves are based on records of various lengths, chiefly from sta- 

 tions located in the valleys of these mountainous counties. Smith's 

 curves are reproduced in figure 5, in which they have been brought 

 half way down toward the base hne in order to make them comparable 

 with the curve expressing the average summer rainfall of the Santa 

 Catalina Mountains for 1911, 1912, and 1913. The portion of Smith's 

 Graham-Cochise curve extending above 5,500 feet is based on a single 

 short record at 6,000 feet. 



The curve of altitudinal rise of rain for 1911, 1912, and 1913 in the 

 Santa Catahnas is merely a simple average of the actual readings for 

 the three summers, without any attempt to correct in accordance with 



Fig. 5. — Graph showing altitudinal increase of summer rainfall on the Santa Catalina Mountains 

 in 1911, 1912, and 1913 (solid line) ; together with Smith's curves for Pima and Pinal Counties, 

 Arizona (dotted line), and for Cochise and Graham Counties (broken line). 



Fig. 6. — Graphs showing vertical increase of summer rainfall in the Santa Catahna Mountains in 

 1911 (solid line), 1912 (broken line), and 1913 (dotted line). 



the departure of the neighboring lowland rainfall from the normal 

 during these years, without the application of any rainfall formula, 

 and without the smoothing of the lines. Reference to table 4 will show 

 that the record for 7,000 feet is based on two years only, and the record 

 for 9,000 feet on one correct summer's reading and the reading of one 

 summer in which the gauge overflowed. 



A comparison of Smith's curves with the curve for the Santa Cata- 

 linas shows the latter to have a sharper rise from 3,000 to 4,000 feet, 

 and to have a relatively level stretch from 4,000 to 6,000 feet, where 

 the former curves have their sharpest ascent. 



* Smith; G. E. P., loc. cit. 



