Clouds are made up of water or ice crystals. The individual droplets or ice crystals are too small to see without a telescope. When the sun reflects on a cloud, the cloud appears white, gray or blue. Generally, the darker the cloud appears, the thicker the cloud. There are four main categories of clouds. Each type of cloud is classified as one of these four or as a combination. Stratus clouds, from the Latin for layer, are low-level clouds that may or may not contain precipitation. Altostratus clouds are mid-level clouds. Cirrus clouds are high-level clouds that typically signify fair weather. Cumulus clouds have a dramatic, vertical development and will often turn into cumulonimbus clouds producing thunderstorms. Add the prefix nimbo or the suffix nimbus to a cloud type and it means there is precipitation associated with a particular cloud. Cloud types that contain the prefix alto are always mid-level clouds. The identification of clouds is a fascinating way to learn more about the earth’s weather.

Comon Types of Clouds

Cumulonimbus

• Cumulonimbus clouds are large, vertically developed clouds.
• Cloud tops may reach as high as 39,000 feet or higher.
• Typically associated with thunderstorms, cumulonimbus clouds contain rain.
• A distinctive anvil shape on the top of this formation is sometimes present.
• Cumulonimbus Cloud Photo
• Cumulonimbus Structure

Cumulus

• Cumulus clouds often appear fluffy, like balls of cotton.
• A flat base is common in cumulus clouds.
• Cumulus clouds are relatively short-lived, with a lifespan of 5-45 minutes.
• Cumulus Cloud Photo

Stratus

• Stratus clouds are uniformly gray, low-level clouds.
• These clouds may contain light precipitation, but never heavy.
• Stratus clouds often appear when warm, moist air meets cold, dry air.
• Stratus Cloud Photo

Cirrus

• Cirrus clouds are high altitude, wispy clouds.
• Cirrus clouds often have a feathery or ribbon-like appearance.
• Cirrus Cloud Photo

Cirrostratus

• Cirrostratus clouds have a sheet-like appearance that covers the entire sky.
• Clouds are transparent – light from the sun or moon shines through cirrostratus clouds.
• A halo will often be observed around the sun or moon when cirrostratus clouds are present.
• These clouds appear ahead of some type of weather front and are often a precursor to inclement weather.
• Cirrostratus Cloud Photo

Altocumulus

• Altocumulus clouds typically appear as parallel bands or rounded masses across the sky.
• The underside of the cloud appears shaded.
• These clouds are gray or blue.
• Altocumulus clouds are a sign of unstable air layers and may precede summer thunderstorms.
• Altocumulus Cloud Photo

Altostratus

• Altostratus is a thinly layered, mid-level type of cloud.
• Sunlight can be seen through altostratus clouds.
• Altostratus Cloud Photo

Nimbostratus

• Nimbostratus clouds are dark, low-level clouds.
• Depending on the temperature, a nimbostratus cloud contains rain or snow.
• Nimbostratus Cloud Photo

Stratocumulus

• Stratocumulus clouds are low-level clouds.
• Often lumpy in appearance.
• Typically in shades of light to dark gray.
• Weak precipitation is often associated with these clouds.
• There will often be breaks in stratocumulus clouds that allow the sun to shine through.
• Stratocumulus Cloud Photo