Dew, Clouds, and Rain
T HE sun is all the time heating the water on the land and in the sea, and changing it into vapor, which rises in the air. We cannot see the vapor, but it is in the air around us.
If the vapor in the air is suddenly cooled, a strange thing happens. Some of it quickly changes back into water. You have often seen, in the early morning, little drops of water hanging like pearls upon the blades of grass.
Now, where do these drops come from? They come from the air. The vapor in the air floats against the cold grass and leaves, and is cooled and changed into tiny drops of water. We call this dew.
Of what use is dew?
If the night is quite cold, the dew will freeze. It is then called frost. You have seen the frosty window pane with the beautiful pictures upon it.
Make a picture of the window as you remember it, covered with the pretty things made by the frost.
When vapor rises high in the cool air it is turned into very small drops of water or minute crystals of ice, and we can see it floating about in the air. It is then called a cloud. Almost any clear day you may see clouds form and then seem to melt away.
You have seen on a blue sky, light, fleecy feather-clouds. They are very high up, and it is very cold where they are. You have also noticed the clouds at sunset with their beautiful colors. As the sun sank lower and lower, how did they change, in shape and color?
When clouds are low down, near the earth, we call them fogs or mist.
If clouds are cooled, the little particles of water gather into large drops and fall as rain. If the drops should freeze in falling, we would call them hail.
What shape are the raindrops? Of what use is the rain?
Sometimes, when it is very cold, the moisture in the air freezes before it forms into drops, and falls in the beautiful flakes we call snow. Have you ever seen snowflakes through a microscope?
Snow keeps the roots of plants warm. Many plants would die in winter if it were not for the snow. What other uses has snow?
Observe the clouds, fog, rain, snow, dew, frost, and tell what you have noticed.
Write what you have seen or noticed about vapor, clouds, rain, etc.