Yorkville enquirer. [volume] (Yorkville, S.C.) 1855-2006, 1911-08-18
HOW THE EARTH is WARMED
Manner In Which the Suns Rays Sup
pIy Necessary Heat for the World.

Prof. Sir ]. ]. Thomson's recent lee
ture on the amount of energy trans
mitted by the sun to the earth is OF
more than ordinary interest at the
present time. The lecture dealt with
the possibility of using the suns en-
ergy, estimated at not less than 1000
horse power per acre on bright
sunny day. 1t is most lavish expen-
diture, but practically wasted because
nobody quite knows how to use it. II
suggests the possibility of obtaining
power at less than half the cost Of the
cheapest hitherto obtainable, and al
the sacrifice of only a degree or so OF
temperature. This would never be
missed. The power of the sun, how
ever, is not heat altogether. The SCI
enlist calls it radiant energy. How
then. is the earth warmed? AS spring
is advancing and the average daily
temperature is rising it may be profit
able to find an answer TO this ques-
ton.
The sun is the fire which warns
the earth's surface, but its heat Is
only felt when it falls upon bodies
whose temperature can be raised. TIC
gain an idea of the suns power and
brilliancy we may roughly compare il
to the light produced by the electric
current when it leaps across a small
air-gap between two rods of carbon
This tiny flame is known as the elec-
trio arc, and it will light a surface OF
several hundred square yards. The
face of the sun is q millions Of mil.
lions of square miles, and its bril-
liancy is more than double that of the
electric light. In point of size, the
sun is 500 times larger than all the
planets put together. Compared sole
ly with our own planet, 1t would take
10000 of earths to make a globe
about as large as the sun. OF all the
heat which the sun sends off the earth
receives but a small fraction, which is
said to be less than a two-thousand
milliOnth.
Sir John Herschel and Pouillet, in
dependently of each other, investi-
gated the actual amount of heat re-
ceived on the earth, and calculated
the total amount which the sun emit
ted. Basing their calculations upon
the rate at which the sun melts ice
they found that the heat from an
overhead sun falling on a square mile
of the earth's surface would melt 26,-
900 tons of ice in an hour. The total
amount of heat radiated from the
sun in a given time has been calcu-
lated from the amount which the
earth's surface receives in a given
time. And it has been expressed in
various ways. 1t could melt 1850
trilliOns of ice in an hour. If the
earth were made of ice, two minutes
exposure to the whole heat of the
sun would melt it; in two minutes
more all the water would be boiling;
in fifteen minutes after the ice began
10 melt all the water would be con-
Verted into steam.
The suns heat varies in different
parts of the earth. Whether it be
much or little, the first thing to get
warmed is not the air. as is common
ly supposed. but the surface Of the
earth itself. The air is warmed chief
ly by contact with the ground, and
dry air is never heated at all. In this
connection a good word can be said
for our own "beastly climate" A
damp climate has certain advantages
over a dry one, because the salvation
of any climate is really the supply OF
water vapour or damp air which the
atmosphere contains. Abolish damp
air and if the earth's heat from the
sun would radiate rapidly away Its
presence arrests the heat and keeps
the earth warm. 1t is for this reason
that in dry climates the days are
warm and the nights cold. A fog
bank. enshrouding the earth some
times like pail has its uses. 1t acts
as blanket which. in spite of its be-
ing a wet one, prevents the earth's
surface heat from passing away
Without a vapOr blanket we should be
exposed every night to the most in
tense cold, to something approaching
49O degrees below zero. In fact with
out damp air the earth could not be
habitable. Had it been made like a
mirror and reflected back the heat II
received it could never be warmed.