The Colorado Experiment Station 
io 
It has been estimated that the sun’s rays, in passing from the upper 
boundary of the air to sea level, lose 20% of their heating effect. 
Shortness of growing season is compensated for, in a large meas¬ 
ure, by the intensity of the sun’s rays. 
Absolute Annual Range of Temperature. —The absolute an¬ 
nual range of temperature is the difference between the highest 
and lowest temperatures of the year. This range gives us an index 
of the severity of the climate, although not always a reliable one. 
Very low temperatures with a snow cover on the ground are less 
harmful to vegetation in the dormant state, than when there is no 
snow cover. The following table gives the absolute annual range 
of temperature for a few Colorado localities. The temperatures 
• are for the shade, as are all ordinary meteorological records. 
TABLE IV.—ABSOLUTE ANNUAL RANGE OF TEMPERATURE (1915). 
Altitude 
Absolute Annual 
Station 
County 
(in feet) 
Range of Temperature 
Arriba . 
5243 
100 
Aspen . 
7909 
106 
Beuna Vista. 
7955 
95 
Boulder . 
5346 
98 
Castle Rock . 
6220 
116 
Cheyenne Wells . 
4279 
107 
Colorado Springs.. . . . 
6098 
98 
Delta . 
4965 
115 
Denver . 
5272 
98 
Durango . 
6534 
99 
Ft. Collins. 
4985 
106 
Frances . 
9300 
88 
Garnett . 
7576 
114 
Grand Junction. 
4602 
101 
Gunnison. 
7670 
125 
Holly . 
3380 
108 
Lake Moraine . 
10265 
93 
Lamar . 
3592 
117 
Lay . 
6190 
116 
Mancos . 
. .Montezuma. . . . 
6960 
96 
Meeker . 
6182 
105 
Montrose . 
5811 
107 
Pueblo . 
4734 
103 
Rocky Ford . 
4177 
110 
Salida . 
7035 
111 
Steamboat Springs . 
6683 
125 
Victor. 
10100 
86 
Wagon Wheel Gap Exp. Station. 
. .Mineral . 
9600 
86 
Westcliffe. 
7864 
119 
Difference Between Air Temperature and That of Soil and 
Plant Surfaces. —The temperature of soil and plant surfaces dur¬ 
ing the day usually, not always, exceeds that of the surrounding 
air. There is an increase in this difference of temperature with 
elevation above the sea level. High surface temperatures in the 
mountains, during the time that the sun is shining, compensate in 
