Squeezing water from air
Water is almost always in the air around you, even when you can’t see it
or feel it. Here is an experiment that will show you how clouds form
when cold air and warm air come together. You’ll need:
a drinking glass (glass—not a spoon
paper or plastic) ~a\ pot\ of\ water~
ice cubes
Do this experiment in the kitchen. To make sure the air is damp, have a
pot of water boiling on the stove. (Ask someone for help if you need
it.)
Fill the glass halfway with water. Make sure the outside of the glass is
dry. Then put some ice cubes in the water and stir them slowly. After a
few minutes, you will see that the outside of the glass looks frosty and
feels wet. What happened?
water droplets forming on a cold glass
The outside of the glass was dry when you began, but the warm air in the
kitchen was damp. It was full of water vapor—water in the form of a
gas.
Water vapor is made up of tiny things called molecules. These molecules
of water vapor are spread out and moving around in the air. But when
some of the molecules touch the cold glass, they condense, or come
together, to form water droplets on the glass.
Clouds form in the same way. Warm air, with water vapor in it, meets
cold air. Where they meet, the water molecules get very cold. They
condense and become tiny droplets of water or bits of ice.
