Students learn early that clouds are "puffy balls of cotton" in the sky. However, many may not realize that clouds are really another form of water. Evaporation or the process involved in changing water from the liquid state to the gaseous state is very important in the conversion. Introduce to students that clouds are really the gaseous state of water and are produced within the atmosphere.
Clouds are groups of tiny droplets of water, or sometimes ice, that form around dust in the atmosphere. Water remains suspended in the air, because the drops are so tiny, Clouds are usually described by technical names (i.e., cumulus), but they can also be described by what they look like (i.e., puffy). Usually learning the technical names is not difficult for children, as long as they have an associated image. Do not give the children these terms unless you have pictures associated with them.
A system for naming clouds was developed by Luke Howard, an English pharmacist in 1803. He identified ten distinct categories of cloud, all of which are variations on three basic cloud forms including puffy cumulus clouds, stratus clouds forming in layers, and feathery cirrus clouds. This system proved so simple and effective that it is basically used by meteorologists today.
There are 4 major terms that help describe clouds. "Stratus clouds," are grey, and float low in the sky, flat as sheets and may bring rain or drizzle. "Cumulus clouds" are white, and pile high in the air. That means fair weather is coming. "Cirrus clouds” are white and curly. They float highest of all and bring a change of weather. "Nimbus” in a cloud name refers to clouds that are dark, which usually mean rain or snow. Cumulo-nimbus is a cumulus cloud that usually means rain in the forecast. Fog is just a cloud that is close to the ground.
Scientifically clouds are classified by their altitude and a combination of the stratus, cumulus, cirrus, and nimbus to further sort them. However, students need to associate nimbus, stratus, cirrus, and cumulus with correct images before they can really learn to describe the clouds that they see in the sky.