CLIMATE OF THE SANTA CATALINA MOUNTAINS. 65 
curves show the averages between the south and north slopes for each 
station at each reading, being expressed in cubic centimeters of evapo- 
ration per day. Here again is brought out the pronounced fall in 
CC.» 
120 
"OF 
100; 
390- 
80- 
70 
60r 
50- 
40- 
1 1 1 
APR. MAY JUNE 
1 
JULY | AUG, SEPT. 
Fie. 11.—Graphs showing seasonal march of evaporation rate at 6 altitudes in the Santa Cata- 
linas in 1911. Amounts are average daily losses from the atmometer, and each reading is 
the average of one on a north slope and one on a south slope. 
rate which follows the advent of the summer rains and the cloudy 
and relatively humid weather by which they are accompanied. After 
the period of heavy rains by which the 
humid mid-summer was opened in the last 
days of Juneand early days of July there 
was a slight rise in evaporation, followed 
by a slight fall in late August and early 
September. The curves for 3,000 and 
4,000 feet accompany each other closely 
after the first two readings, and the curves 
for 6,000 and 7,000 feet accompany each 
other closely throughout the summer. 
The curve for 8,000 feet stands always 
well apart from that for 7,000 feet. The 
grouping of these curves is, therefore, 
analogous to the natural subdivisions of 
thevegetation. Thereadingstakenin the 
cc 
400 T T T T 
n 4 n 1 
3,000 4,000 9000 6.000 7.000 8000 
Fie. 12.—Graphs showing altitudinal 
decrease in rate of evaporation in 
the Santa Catalinas in arid fore- 
summer (heavy line) and humid 
mid-summer (light line) of 1911. 
Desert region at 3,000 and 4,000 feet, those taken in the Encinal and the 
lower edge of the Forest at 5,000, 6,000, and 7,000 feet, and the one series 
