The Kennewick courier-reporter. [volume] (Kennewick, Wash.) 1914-1938, 1925-04-09


bodies in actual contact is called con-
duction. The rapidity with which
the heat is transferred from one part
of the substance to the other indi-
Gates whether the substance is good
or poor conductor. Iron is an excel
lent conductor while wood is very
poor conductor of heat. The earth
and the atmosphere surrounding it
are very poor conductors of heat.
Radiant energy is a minute wave
disturbance. The sun is constantly
radiating energy about one two-bil-
lionth of which is received by the
earth. The radiant energy striking
the earth makes itself manifest in
one of four different ways. 1t may
heat the object upon which it strikes.
If the waves enter the eye they will
| produce vision. 1t is only the waves
of intermediate wave length that
causes vision, however. 1t may pro-
duce a chemical change. An example
is the exposure of Photographic
film. Only very small part is used
up in the causing of chemical chang
es. The fourth effect is the chang
ing of state. A large amount of the
radiant energy which falls upon bod
les of water is expended in evaporat-
ing part of the water and causing it
to pass into the atmosphere as
vapor. We are concerned only with
the first process here.
The energy radiated from the sun
passes to the earth thru the 100000
the enormous rate of 186,330 miles
per second. Because of the dust par
900 miles of intervening space at
ticles, water vapor, etc. In the air
considerable resistance is offered to
the passage of the radiant energy
thru it with resulting heating of
air in immediate contact with the
earth. All substances radiate energy
at all times. If the outgoing radia-
ton exceeds the incoming, the SUBJ
stance cools. The converse is also
true. The earth is constantly rad
iating heat to the upper limits of
the atmosphere, region of intense
cold. During the day the heat re-
ceived from the sun is far in excess
of the amount given off by the earth
and the temperature of the earth ris-
es. After the sun sets there is no
heat received to counterbalance that
given off and the earth cools.
During clear, calm days the tenn
perature of the earth is raised by
the radiant energy received from the
sun and the air in immediate contact
is warmed by conduction. Since the
air is poor conductor only the air
in immediate contact with the earth
is warmed at first. But, as the air
becomes lighter and the cold air
around and above it forces it to rise.
This is called convection. Cold air
rushes in to take the place of the
rising warm air and it in turn is
warmed and the process goes on as
long as the earth is receiving more
heat than it is radiating. The air
becomes warmest near the ground,
decreases in temperature at nearly
a uniform rate with increased dis
lance above the earth up to 1000 feet
or more.
AS soon as the sun sets the earth
cools rapidly by radiation and its
temperature falls. The air in con-
tact with the ground looses heat to
the ground by conduction. The air
near the ground becomes increasing
" colder and its density greater. This
increased density keeps the cold air
in contact with the earth. Conse-
auently on clear, calm nights there
is layer of relatively thin cold air
near the earth and the temperature
increases with an increase in eleva-
ton up to an altitude of between 100
and 500 feet.
1t is this layer of warm air that
makes orchard heating possible. In
the cold air below this layer is where
the heat is applied and the tempera-
ture of it alone is raised. Because
of the varying distance of this warm
LAYER above the earth no definite
temperature rise can be attributed to
any heating device. On one night
the layer may be comparatively low
and a ries of 10 degrees or more may
be easily attained. On another night
the layer may be considerable higher
and a raise of or degrees may be
difficult to secure.
FROST BITES