Clouds and Precipitation

Clouds form when water vapor condenses and droplets of water or ice crystals accumulate in the atmosphere. Clouds are categorized by their shape and altitude. The three main types of clouds are cirrus, stratus, and cumulus. Each cloud type is associated with different weather.

Cirrus clouds are thin, wispy clouds that form at high altitudes and are composed of ice crystals. Stratus clouds form in layers that spread across the sky and often bring continuous rain or snow. Cumulus clouds are large, puffy clouds that are typical of fair weather.

A cumulonimbus cloud is a very large cumulus cloud that is responsible for thunderstorms and extreme weather. Altocumulus and altostratus clouds form in the middle of the atmosphere, above 6,000 feet. Stratus clouds that form close to the ground are called fog.

Precipitation is water that has condensed in the atmosphere and falls to the Earth. Rain, sleet, snow and hail are different forms of precipitation. The type that falls depends on the temperature.

Rain typically falls from stratus clouds in the form of a drizzle or mist. Sleet is a mixture of water and ice, while snow is basically water that has crystallized. Hail forms during a thunderstorm when water droplets move through a cycle of rising, freezing and falling inside a cumulonimbus cloud.