Water in the air seen in fog.
Commonly the water in the air is not seen, as I have before told you; but sometimes you can see it. You see it in the breath in a very cold day. The cold air makes it look like smoke coming out of the mouth. You see it, too, in the fog. When there is a fog there is a great deal of water in the air. The reason that you can see it is that the particles of water are not as finely divided up as when the air is clear. They are in little companies, as we may say, but there are not enough of them together to make drops. If they were in companies large enough to make drops, they would fall to the ground—that is, we should have a rain.
A beautiful scene.
Sometimes the fog is every where; sometimes it hangs only just over the water. If you are on a very high hill, where you can look off and see a river in the distance, you can sometimes see in the morning a line of fog stretching along where the river is, while it is nowhere else. I once saw a very singular and beautiful scene made by the fog. I had been out on horseback in the night to visit a sick person. As I returned, just before sunrise, I saw from a very high hill a thick fog over all the river below. From the river arose high hills, irregular in their shape, and on the sides of these hills were houses at different heights. The lower houses were all so covered by this dense fog that I could not see them, while those that stood high up on the hills I could see as plainly as ever. It looked as if a sea had come in while I was gone on my visit, and had filled up the valley where the river ran, for the fog rose to the same height on the sides of all the hills. Many of the houses stood upon the very edge of this sea. The scene was so beautiful that I waited to see the sun rise upon it. As it rose, it shone over the tops of the hills, and lighted up this sea of fog, which it in a little time scattered by its heat.
Dense fogs often hanging over large cities.
Very thick fogs often hang over large cities, while all around in the country the air may be perfectly clear. London is often covered with such a fog. Sometimes it has been so dense that people could not see to do any business. It is related that the fog over the city of Paris was once so thick that persons who went about with torches often ran against each other, because even lights could not be seen unless they were very near. And in Amsterdam, in a fog in the year 1790, there were over two hundred persons drowned by falling in the darkness into the canals which run through every part of that singular city.
Questions.—What becomes of the water when a cloth is dried? Tell about the drying of ink on the paper. Tell about water’s going up in the air after a shower. Can you commonly see the water that is in the air? Does water go into the air from things that do not appear wet? What is said about its going from the skins of animals? Tell about the experiment with the glass jar. What is said about water’s being breathed out from the lungs? In what ways do you see this shown? What is said about water’s being in constant motion? When there is a fog, why is it that you see the water that is in the air? Tell what is said about fogs. Tell about the fogs that hang over large cities.
CHAPTER XX.
CLOUDS.
Clouds made of fog.