222 
portion is only one of degree. The temperature will change with alti. 
tude and latitude, and the moisture among the mountains will be greater 
than on the plains. 
That we may enter more intelligently upon the consideration of the 
climate of Colorado, we will briefly glance at the various influences that 
control a climate. 
Great altitude has perhaps the most important influence on climate, 
because of the rarity of air that accompanies it, producing rapid evap- 
oration, dryness, variability, and extremes of temperature, clearness 
of skies, and all the effects opposite to those of the sea-level, where the 
thick stratum of humid atmosphere intercepts the sun’s rays, retains 
heat, obstructs radiation, and produces equability of temperature. Low 
humidity is the main characteristic of high elevations, and is caused 
principally by the lower temperature reigning at such elevations, but 
also by the diminution of atmospheric pressure, allowing less moisture 
to be held in a given space of air at a given temperature than at lower 
levels. Authorities state that there is an average lowering of tempera- 
ture of three degrees Fahrenheit for each thousand feet of ascent, and 
this cooling lessens the capacity of air to contain moisture. 
Latitude has a strong influence on climate, acting in much the same 
way as altitude; the effects of a high degree of latitude being, in a gen- 
eral way, similar to those of a great-altitude. Professor Loomis states 
that beyond the parallel of sixty degrees north latitude, at a short dis- 
tance from the ocean, the mean annual rain-fall seldom exceeds 10 
inches. 
Distance from the ocean naturally promotes dryness, and to this fact 
is due, in no small degree, the uniform lack of humidity in the atmos- 
phere upon the extensive plateaus of Wyoming, Colorado, and New 
Mexico, which is not found in the high altitudes of Switzerland. The 
evaporation constantly going on over the ecean and all bodies of water, 
supplying the atmosphere with moisture, which returns to the thirsty 
land in rain, is wanting in the elevated interior of our continent. And 
there can be no satisfactory compensation on our open plains for this ab- 
sence of water distribution, as long as there are no forests, undergrowth, 
or thick grasses to prevent evaporation and drying of the land, and to 
provide by their natural reservoirs and springs and differences of tem- 
perature a substitute for the ocean. Afar inland position also has a pow: 
erful influence upon temperature. The specific heat of land being only 
one quarter that of water, it both absorbs and gives out heat more rap- 
idly, consequently the more land the greater the heat and the wider the 
fluctuation, especially when there is nothing to obstruct the sun’s rays 
or the earth’s radiation. 
High mountain ranges exert a powerful influence upon the moisture 
conditions of a climate, by intercepting the air currents which come 
from a distant, warm, damp region. Such currents are quickly brought 








