CLOUDS.
[Sidenote: Clouds made of fog.]
You see water in the air in another shape besides fog. You see it in
the clouds. A cloud is really fog, but it is high up in the air, while
what we commonly call fog is near the ground.
[Sidenote: Mists.]
Sometimes rain comes from the clouds, and sometimes they give out no
rain. Why is this? When the clouds do not rain, the water in them keeps
in the state of fog. The particles are all in small companies; but
when the rain comes from the clouds, it is because the cold air makes
the particles gather into larger companies, so as to form drops. Then
they fall. A mist is different from rain in this way--the companies
of particles are not as large as in rain. On the other hand, they are
larger than they are in fogs or in clouds.
[Sidenote: How the rain is made to come from clouds.]
You remember what I have told you about the gathering of water upon the
tumblers in warm weather. It is the coldness of the tumbler that does
this. It gathers, or _condenses_, as we commonly say, the water in the
air into companies or drops on the tumbler, just as cold air coming
upon a cloud condenses the water into drops that fall to the earth in
rain.
How swiftly these collections of water, the clouds, are sometimes
carried along by the wind! It seems as if they were chasing each other
across the sky.
[Sidenote: Shapes of clouds.]
How different are the shapes of the clouds! Sometimes they lie along,
stretched out like long straight stripes; and sometimes they are in
heaps, piled up one above another. Then, again, they are spread like
feathers. It seems strange that fog high up in the air should collect
into such different forms, when near the ground it always appears very
much the same.
[Sidenote: Their beauty.]
At morning and evening the clouds are often very beautiful. How do
you think that the rich bright colors are made? They are made by the
sun shining upon the little companies of water-particles of which the
clouds are made. I will tell you more about this when I come to speak
of Light.
The clouds are not so high up in the air as most people think they
are. Some clouds are higher than others, because they are lighter;
and sometimes you can see the clouds that are very high up going in a
different direction from those that are nearer to the earth. This is
because there are often currents of air very high up that do not go
the same way with the winds below. Persons that go up in balloons have
found this to be so, as I have before told you.
[Sidenote: Clouds about mountains.]
Clouds are often seen about the sides of high mountains while the
sun is shining upon their tops; and persons that are on the top of a
mountain may sometimes see clouds below them, while the sky is clear
overhead. I was once on the top of Catskill Mountain when a shower
passed over. The cloud, after it had passed over the mountain, spread
over the country below, so that I looked down upon it. As the cloud was
rather a thin one, it was broken into parts. The sun, therefore, shone
through the openings here and there; and I remember seeing through one
opening in the cloud a beautiful spot, where there was a farm-house
and a pond near by, lighted up by the bright sun shining through
another opening.
[Sidenote: What goes up from the earth to make clouds.]
It is the water that goes up from the earth into the air that makes the
clouds. I have told you from what a variety of things this water comes.
Even the perspiration from your skin and the moisture that is breathed
out from your lungs often help to form the clouds that you see floating
so high in the air.
As I have told you before, water is ever changing, ever moving. It is
silently going up into the air from almost every thing on the earth.
Then you see some of it moving along in the clouds. It falls down in
the rain. It runs in the brooks and the rivers. In the sea it is lashed
into waves by the wind, and is so continually in motion there that the
restless sea is a common expression. Water is always going somewhere.
Even in places where it seems to be still, it is not so; even there,
some of it is all the time going up into the air, and other water comes
to take the place of that which goes up.
[Sidenote: Water a great traveler.]
Water is a great traveler. If any particle of water could write its own
history, and tell where it had been ever since it was created, what a
varied history it would be! Now it is tossed in the waves; now it is
flying off in the air on the wings of the wind; now it is in a cloud;
now it falls in a drop from high up in the air; now it sinks into the
ground, and is sucked up by some plant; and now, perhaps, from the
plant, eaten by some animal, it goes into the blood of that animal.
Thus it goes every where and in all sorts of company. Clean as is the
draught of water that so refreshes you, it is made up of particles
that have been in company with all sorts of things, clean and unclean,
in all parts of the earth.
Observe in what very different ways the water takes its start to go
off up into the air. Much of it goes up from the ground, and from the
surface of lands, and lakes, and seas, and rivers; but a great deal
also is sucked up from the ground by the roots of trees and plants, and
travels up to the leaves to take its flight into the air from them. And
then, too, animals drink water, and eat it in their food, and some of
this flies off into the air from their skins and lungs.
[Sidenote: Water goes up in the air in various ways, and comes down in
different forms.]
The water that goes up in these different ways has also different ways
of getting down upon the earth again. That which is high up in the
form of clouds comes down in different shapes. When cold air meets the
clouds, and changes the water so finely divided in them into drops, it
falls in rain. When the air is cold enough to freeze it, it falls in
the shape of snow or hail.
_Questions._--What is a cloud? Why does it not always rain when it
is cloudy? What is the difference between mist and rain? Give the
comparison between the rain and the gathering of water on a tumbler.
What is said about the shapes of clouds? What about their colors at
morning and evening? What is said about the heights of clouds? What
about clouds around mountains? Tell about the shower on the Catskill
Mountain. What is said about the moisture from your skin and lungs?
Tell how the water is always moving and changing. What is said about
water as a traveler? Tell in what different ways the water goes up in
the air. In what different ways does it come down, and why?