Water can exist as a gas, liquid, or solid. Clouds are formed when air contains as much water vapor (gas) as it can hold. When the water in the cloud gets heavy enough, it falls out of the air as rain or snow.

Fog and clouds are the same. If the moist air is lower that 50 feet, it is fog. If it is higher, it is a cloud. There are two types fog. One is created during the night as the ground cools, thus cooling the air above it. The other type is formed when warm moist air moves over a colder surface.

Clouds can form anywhere in the troposphere and can move from place to place with the wind. There are different types of clouds, based on their appearance and height above the ground.

Cirrus clouds look like hair or feathers blowing in the wind. They are very high in the sky where the air is cold. The moisture in these clouds is frozen into ice crystals instead of water droplets. Strong winds blow these clouds in long streamers across the sky.

Stratus clouds look like sheets across the sky. They form when condensation happens at the same level at which the air stops rising. They often bring rain.

Cumulus clouds are puffy and can be many shapes and designs. These clouds have flat bottoms and billowy tops. There are other clouds that are combinations of these three types.

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Last modified: Tue May 12 16:30:53 PDT 1998

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