"To-day we come to that subject which we should have looked at a week ago,
if that I hope not unprofitable discussion of the uses of trials and the
ministry of pain had not prevented. We must now examine the arrangement
for softening the rigors of winter and toning down the heat of summer. The
general principle is that in summer the earth receives an excess of heat,
while in winter the opposite is true. These extremes are mitigated by
transferring heat from summer to winter. How is this accomplished? Any one
who has thoughts upon this subject may answer."
"I have some thoughts," said Ansel, "but whether right or wrong, I cannot
tell. I should think heat might be carried from summer to winter in the
same way as from day to night."
"What are some of those means for transferring heat which seem to you to
operate the same in the annual as in the daily changes of temperature?"
"One is the absorption and radiation of heat, and another is the
evaporation of water and the condensation of vapor."
"You are right," said Mr. Wilton. "The effect of these operations in the
equalization of the annual extremes of heat is in no wise different from
their effect upon the temperature of day and night, but from summer to
winter their effect is vaster and more impressive. During the summer, sea
and land, and 'all that in them is,' are receiving heat and rising in
temperature. The heat of summer penetrates and warms the earth nearly a
hundred feet in depth. Into the sea heat penetrates still deeper. How vast
the amount of heat required to warm the whole surface of the earth and sea
to such depths! By withdrawing so much heat from active use the intensity
of the summer temperature is softened. During the colder months the land
and sea slowly radiate their heat. We can hardly over-estimate the effect
of this alternate absorption and radiation of heat. So great is the
effect of this stored up heat that the sea and the great lakes never
freeze even in the coldest winter weather, except in the polar regions,
and the temperature must fall far below freezing and continue for a long
time below the freezing point before the earth begins to freeze. The great
bodies of water, remaining always at a temperature above thirty-two
degrees, are especially important in warming the wintry air. In the
coldest weather they seem like steaming caldrons throwing up their warm
vapor. It is the absorption and radiation of heat alone which prevent the
temperature of the atmosphere from rising or falling suddenly to the
highest or lowest point possible. The sun breaks forth in all its splendor
at noonday in summer: what if the sun were to remain stationary, shining
thus in his strength for days and months? Everything would be consumed
with heat. But why do not the glowing rays of the sun raise the
temperature at once to the highest possible point? Because the earth and
sea and every object upon the earth absorb the heat, storing it up and
holding it in reserve.
Public-domain text, read in full here on John Shaqi.
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