Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1911-08-18
There are three ways in which heat

is communicated, namely, conduction,
convection and radiation. Conduc-
ton occurs when the surface Of the
ground, already warmed, heats the
layer of air that rests upon it. Con-
vection occurs when the heated air
rises and colder air descends, gets
warm and ascends again. The air cur
rents thus produced carry heat along
with them. Radiation occurs when
heat passes from one object to anoth-
er. Heat is continually radiated both
by the sun and the earth. In the day
time that portion Of the earth which
is turned to the sun receives more
heat than it gives off. The earth Is
consequently warmed. But why are
the suns rays so powerful at noon
and so feeble in the morning and
evening? 1t is because the heated
power of the rays depends on the
ground. When they strike vertically
their heating power is greatest; when
they are oblique their heat is dimin-
ished; when they are horizontal their
heat is least. This also explains why
the poles of the earth are so cold and
the equator and tropical parts so hot.
When the sun shines on the poles he
does so from a low elevation in the
heavens. In equatorial and tropical
regions the solar rays are vertical or
nearly so. At each place between
the tropics the sun is vertical twice a
year. That part of the globe is
therefore hottest. In other words, the
earth's heat at any place depends to
a great extent on latitude or distance
north or south Of the equator.
Latitude and temperature, however,
do not always correspond. There is
frequently a vast difference in the
temperature Of places in the same
latitude. For example, If an imagi-
nary line be drawn on a map through
the latitude Of London it will cut Rus
sia at Warsaw on the east, and Cana
da at Labrador on the west. But the
climate Of England, Russia and Cana
da are far from being exactly alike.
The cause Of these variations is found
in the grouping of land and sea. In
some places the suns rays fall upon
large stretches of land, in others upon
wide reaches of water. Of the two
substances the land becomes the hot
ter.
The heat of the surface Of the sea
Is seldom more than eighty-five de-
grees; the heat Of the surface on the
earth at some parts Is 140 degrees.
But, curiously enough, the colder wa
ter is most generous contributor to
the warmth Of the earth. Water alb
serbs heat, not for itself, nor for the
purpose Of augmenting its own heat.
1t ca intake in a great amount of heat,
and willingly distributes it; but dur
ing the accommodating process it's own
temperature does not acquire a pro-
portional increase. This capacity of
substances to imbibe heat into their
mass without themselves being equiv
oil a1 hry ic n al,
specific heat. Water Is thus a most
convenient and economical heating
apparatus. 1t takes in the suns heat
and gives it out again. 1t can con-
tinue giving 1t out for a considerable
time before its store is expended.
One seldom thinks Of sunshine be-
ing imported by sea, and yet because
of it's liquidity and mobility the sea is
the bearer of warmth to many lands,
it's hoard Of heat causes warm winds
to rise and blow upon the shore. The
Mediterranean, for example, closed to
the cold currents coming from the
northern regions and bearing a cargo
Of ice is constantly receiving and dis
tributing heat. But the most striking
instance to the effect which water has
on temperature Is to be found in the
influence of the Gulf Stream. The
cause Of this current of warm water is
believed to be the winds perpetually
blowing from east to west over the
tropical seas. The heat Of the stream,
or greater part Of it, is hidden
store which it slowly diffuses wher-
ever 1t goes. The stream drifts for
1000 miles before it's goods are de-
livered. In its journey 1t flows to the
shores Of Britain. and even as far
north as the southern borders Of Ice
land and Spitzbergen. 1t makes the
winter climate of these countries so
much less cold than it would other
wise be, and brings the warmth which
keeps harbors open, while others
which are further south get blocked
by frost. 1t Is hard to believe that
the perennial green Of England, Scot
land and Ireland is due to a big body
Of water which has been heated un-
der a tropical sun. The Gulf stream,
however, may not be the sole cause of
all these effects. There is a barren
tract, known as the desert Of Sahara,
which acts like a huge furnace, and
sends hot winds across Europe. Our
balmy southern breezes are made in
Africa.-T. P.'s Weekly.