Water vapor is often carried far above the ground. The molecules of water vapor have less mass than those of other parts of the air. As the molecules are carried higher, they come to cooler levels. At some height above the ground, the dew-point temperature is reached. Tiny drops of liquid water then form around bits of solid matter, such as dust. If there are enough tiny drops of water in one place, a cloud is formed. Sometimes the air is cold enough for ice crystals to form. A cloud is billions of tiny drops of water and ice crystals.
Clouds come in many different shapes and sizes. Cirrus means “curl.” Clouds that look like white soft feathers are called cirrus clouds. They are formed very high in the atmosphere. Each of these clouds is made of ice crystals instead of tiny drops of water? Even though cirrus clouds are formed in fair weather, they are often a sign of a change in the weather.
Stratus means “layered.” Stratus clouds often cover the sky like a thick blanket. Stratus clouds sometimes bring rainy weather.
Cumulus means “heap.” These white, fluffy clouds are most often seen in fair weather.
Here are some more kinds of clouds. How are they like the three other kinds of clouds? How are they different?
For a few days keep a record of the clouds in the sky. Name and record them. What kind of weather follows each cloud?