4 The Colorado Experiment Station. 
variations caused by the difference in topography, the effect of the 
Rocky Mountains extending through the State, are well defined in 
many cases and cause many complex effects. Many important local 
features are not apparent in the averages of the principal atmos¬ 
pheric conditions which make up what is known as “climate.” Two- 
fifths of the State is highly mountainous, and the rest of it plains 
and high mesas. About 40% of the area is above 7,000 feet in 
elevation. That portion of the State lying east of the mountains, 
or the plains region, is crossed by a ridge which forms the water¬ 
shed between the South Platte and the Arkansas rivers. The low¬ 
est point in the State is where the Arkansas river leaves the State a 
few miles below Holly, at an altitude of 3,370 feet, while Julesburg, 
3,460 feet, on the South Platte, is the lowest point in the northeast¬ 
ern portion of the State. 
A prominent feature of the mountain region is the number of 
large upland parks. North, Middle and South Park, and the San 
Luis Valley in the southern part, a remarkably flat, immense basin, 
which at one time was evidently a lake or sea bed, are all 7,000 to 
t 0,000 feet in elevation. The average height of timber line is 
about 11,500 feet, varying from 10,000 to 12,000 feet. 
The mean temperature of the State as a whole, is 45 degrees, 
and the average precipitation 15.60 inches. Our position south of 
the track of the majority of the storms as they cross from north of 
Montana to the Great Lakes and beyond, and being in the interior 
of the continent remote from the ocean, with our differences in alti¬ 
tude and diversified topography, are features which greatly modify 
the climate at differnet points. The usual track of storms being 
some distance northward, the State is generally dominated by the 
warm and dry quadrants of the low areas that move eastward with 
great regularity, and escapes in part the attendant precipitation of 
moisture, the high wind movement and the sharp fluctuations of 
temperature. Considering the great distance from the Pacific and 
the high mountain ranges which the westerly winds must cross, it is 
not surprising that the low humidity is attended by a great range of 
temperature. 
Normal pressure distribution, with the result on the resulting 
direction of the winds, cause an important effect on our climate. 
During the winter the high pressure of the Salt Lake region re¬ 
maining fairly constant, the effect this has on any locality depends 
upon its location, whether east or west of the mountains. To the 
west is found persistent cold for the latitude and altitude, especially 
in some of the higher valleys. The clear skies and still atmosphere 
cause radiation to proceed rapidly, and the topography causes a 
steady flow of cold air from the higher points into the valleys. On 
the eastern slope at such times the resulting winds are westerly, 
