By observing clouds, you can often predict the incoming weather! See our Guide to Clouds with pictures of the most common cloud types in the sky (classified by altitude and shape)—and what weather clouds predict!
Types of Clouds
Some clouds are as high as a jet; others are near the ground. Some are white puffs and some are grey and lumpy. Overall, there are three different types of clouds: high, middle, and low.
I. High Clouds
Bases start above 20,000 feet, on average
1. Cirrus: Thin, feather-like, wispy clouds which are strands of ice crystals. Weather prediction: A change is on its way!
Image: Cirrus Clouds
2. Cirrocumulus: Thin clouds that appear as small “cotton patches.” Weather prediction: Fair, but cold. In the tropics, hurricane potential!
Trivia: Sometimes, this is a called a “mackerel sky” based on the folklore, “Mare’s tails and mackerel scales make tall ships take in their sails.” These clouds can precede an approaching warm front. Warm fronts can bring veering winds and precipitation. So, a sailor might take in his sails.
Image: Cirrocumulus Clouds.
3. Cirrostratus: Thin white clouds that resemble veils that tend to cover the whole sky. They are more commoin winter. Weather prediction: Rain or snow will arrive within 24 hours!
Image: Cirrostratus Clouds
II. Middle- to Low-Level Clouds
Bases start at between 6,500 and 20,000 feet
1. Altocumulus: Gray or white layers or patches of solid clouds with rounded shapes, and they often appear as fluffy ripples. They are made of liquid water, but they don’t often produce rain. Weather prediction: Fair and pleasant!
Image: Altocumulus clouds
2. Altostratus: Grayish or bluish layer of clouds that can obscure the Sun, usually covering the entire sky. Weather prediction: Be prepared for continuous rain or snow!
Image: Altostratus clouds
3. Nimbostratus: Dark, gray, shapeless cloud layers containing rain, snow, or ice pellets. They are often thick enough to block out the Sun. Weather prediction: Gloomy with persistant rain or snow
Image: Nimbostratus clouds
III. Low Clouds
Bases start below 6,500 feet
1. Stratus: Thin, gray-white, sheetlike clouds with low bases covering the whole sky. Weather prediction: Fair, but gloomy. They may bring drizzle or snow but not much precipitation since they are so thin.
Image: Stratus clouds
2. Stratocumulus: Rounded cloud masses that form in a layer. Often, they have a darkish instead of bright white. Weather prediction: Fair weather for now, but a storm might be on its way.
Image: Stratocumulus clouds
IV. Low Clouds With Vertical Development
Form at almost any altitude and can reach to more than 39,000 feet
1. Cumulus: Fluffy, white, cotton-ball clouds with flat bases and dome-shape tops. Weather prediction: Fair-weather in store!
Image: Cumulonimbus clouds
2. Cumulonimbus: Large, dark, vertical clouds with bulging top that can grow to towering heights on hot, humid days. Weather prediction: bring showers, thunder, and lightning.
Want to see more cloud pictures? Imagine clouds shaped like jellyfish and flying saucers! See Rare Clouds and Pictures.