8 
The Colorado Experiment Station 
TABLE I.—DECREASE IN TEMPERATURE WITH INCREASE IN ALTITUDE. 
Altitude Decrease of temperature per 1000 feet elevation (1915) 
Station in Monthly and yearly means 
Feet. Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. Year 
Salida . 7035 
Leadville .10248 2.5 3.3 3.9 3.2 3.5 3.4 3.1 2.3 2.3 2.9 4.3 3.3 3.2 
Denver . 5272 
Idaho Springs.. 7543 1.4 2.2 1.4 3.0 3.3 2.9 2.9 3.3 3.2 2.9 3.2 2.2 2.7 
Ft. Collins. 4985 
Long’s Pk. ... 8600 1.4 1.9 2.2 3.2 3.1 3.3 3.0 3.0 2.6 1.9 2.1 1.1 2.6 
(near) 
Colo. Springs... 6098 
Lake Moraine. .10265 1.8 2.5 3.2 3.4 3.3 2.3 2.7 2.8 2.9 2.5 2.8 2.4 2.6 
Glenwood Spgs. 5758 
Aspen . 7981—.03 3.2 5.3 5.0 4.1 3.2 2.5 3.1 3.2 2.7 3.1 3.1 3.2 
Durango . 6546 
Silverton 9400 2.3 3.4 4.1 2.9 4.2 5.2 2.2 4.2 3.5 3.1 2.9 0.9 3.5 
Glenwood Spgs. 5758 
Marble ....... 7951 -03 2.0 3.4 2.7 2.3 2.1 1.7 1.8 2.1 2.0 1.7 1.0 0.8 
Garnett . 7576 
Wagon Wh Gap 9610 1.6 3.8 5.2 4.0 4.8 3.9 2.6 3.2 3.4 2.7 2.8 1.6 3.3 
Delta . 5025 
Cedaredge 6175—3.4 0.04 2.8 3.3 3.2 4.6 4.5 .. 2.0 —.01 2.1 0.04 . . 
Boulder . 5347 
Frances . 9300 2.5 2.6 2.0 3.1 3.5 3.8 2.9 2.7 2.7 2.6 3.4 2.0 2.8 
Average.98 2.5 3.4 3.4 3.5 3.5 2.8 2.9 2.8 2.3 2.8 1.8 2.7 
The difference between low and high altitude stations in the 
mean temperatures for January is less than for any other month. 
In fact, the records show that the mean temperature for January, 
1915, at Marble (7,951 feet) is .6° higher than that at Glenwood 
Springs (5,758 feet), and that at Cedaredge (6,175 feet) the mean 
temperature for January of that year was 3.9° higher than at Delta 
(5,025 feet). In general, the differences in temperature between 
low and high altitude stations are less during the winter months 
than during the summer months, as may be seen from Table I. As 
a general rule, it may be stated that in Colorado an increase in 
elevation of 1,000 feet decreases the mean temperature for the year 
about 2y 2 °) for the summer months (June, July, August), about 
3°; for the fall, about 2j4°; winter, about 1^4°; and spring, about 
3j4°. That.is, in order to effect a decrease of 1° in the mean tem¬ 
perature for the year, one must ascend about 370 feet; to effect a 
decrease in the mean temperature for the spring, about 294 feet; 
summer, about 322 feet; fall, about 361 feet; and for the winter, 
about 588 feet. There is a retardation in the development of the 
vegetation, amounting to about 13 days for every 1,000 feet in¬ 
crease in altitude. 
