Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1888-05-10
RAIN CLOUDS.

RAIN CLOUDS.
The Phenomena of Evaporation and Com
densation-How Water Is Drawn into
the Air and WHY 1t Descends.
Did you ever stop to think. when
you looked out of the window and saw
dull, gray clouds from which the rain
was so steadily pouring. and which
seemed to shut in the world all
around. that, in reality, they extend
ed over very small part of the coun-
try; that somewhere else. perhaps
only twenty or thirty or hundred
miles away. the sun was shining. and
all was bright and beautiful? This is
really the case. For storms. however
long and dreary. do not extend over
many miles; and though it always is
raining at some place in the world,
yet always and at the same time it is
pleasant nowhere else. Now, let
us see why this is.
Suppose that on warm summer
afternoon we were to bring pitcher
of clear. cool water, fresh from the
well. and to place it'on the table in
the dining-room. Now, no matter
how carefully we may have dried the
pitcher before bringing it in. we shall
discover, if we watch closely. that the
outside soon becomes wet or misty;
and that the mist grows heavier and
gathers into drops and perhaps even
runs down the pitcher to the table,
Now, where does this water come
from? Not through the sides of the
pitcher, that is impossible; but from
the air. We can not see it. perhaps.
but still it is there in the state of vapor.
How came it thereP Did you ever
notice, after a rain, how in a short
time the puddles became dry. and how
the moisture disappeared from the
grass and leaves. as soon as the sun
shone out and the wind blew? Or,
did you ever notice that if you left a
pan of water out-of-doors the water
each day grew less and less. until all
was gone and the pan dryP
All the water that was in the pud-
dies, on the grass and leaves Except
that which soaked into the ground)
and in the pan. was taken up as vapor
into the air-has 'evaporated. as we
say. The same thing happens when
water boils, only it then evaporates
more rapidly. and we can see the
vapor arising as steam. If you live
near a river, or in country where
there are brooks. perhaps you can see
this evaporation actually taking place.
Get up early some morning. before the
sun rises, and look out toward the
river, You may see long line of mist
or fog, like a big. white cloud, hanging
over the water. Now. this mist is only
the water evaporating from the river
and is just now visible as fog because
the air is cool. And the sun has
shone, the air becomes warmed and
the fog disappears, but the evaporation
goes ON, nevertheless. Indeed. it is
going on continually, and all over the
earth; so that if the water were not
to us as rain, snow and dew.
all the oceans. lakes and rivers would
IN time dry up and disappear All the
trees, grass and plants would then
wither, and our beautiful land would
become as dry and parched as the
great desert Sahara.
Having learned how the water is
drawn into the air. let us see how and
why it comes down again as rain or
snow OF dew.
There is a singular thing about this
moisture, which is this: the air will
hold only certain quantity of it. and
that quantity depends upon the tenn
perature of the air. But warm air al
ways holds more than cold; SO. how
ever warm the air may be, or how
ever much moisture it may con-
tain as invisible vapor. we have only
to cool it enough and the vapor con-
denses, as we say; that is. it becomes
visible, first as fog or mist, and then
rs drops of water. such as we see ON
the pitcher. And the reason we see a
white fog rising at night, after the
sun goes down, is only because the
water, which has been evaporating all
day and going up into the air as in
visible vapor, becomes condensed to
fog by the cooling of the air when the
SUMS heat is withdrawn. When the
sun rises. the fog disappears but the
vapor still ascends and when it reaches
the altitude where the air is always
cool. it becomes condensed again as
fog. only it is then called clouds"
And if it becomes condensed enough
to form in drops of water. they fall.
and 1t ''rains;" or. perhaps. it SHOWS.
for snow is but frozen rain. George
p Merrill. in 81. Nicholas.