1. Cloud Types

2. Main Classifications Cumulus – puffy clouds, that often have a flat base. Some people call them “cauliflower clouds”. They often have the appearance of cotton balls. May cause precipitation (see Nimbus, next slide). Stratus – seemingly endless layers. You cannot see shapes in stratus clouds because they are flat. When stratus clouds are low and dark, they make the day seem dreary. Fog is a stratus cloud at ground level. May cause precipitation (see Nimbus, next slide). Cirrus – thin, wispy, often finger-like clouds that are made of ice crystals. Do not cause precipitation.

3. Naming Clouds Often the name of a cloud is the combination of one of the three major types of clouds with one or more of the following prefixes/suffixes: 1. Rain/Snow clouds: Nimbo/Nimbus – the prefix/suffix given to any rain or snow cloud. Ex: Nimbostratus – a stratus storm cloud Cumulonimbus – a cumulus storm cloud 2. Altitude: Cirro – High level clouds (above 7000m). Made of ice crystals Ex: Cirrocumulus – a high-level cumulus cloud Cirrostratus – a high-level stratus cloud Alto – Mid-level clouds (clouds between 2000m and 7000m) Ex: Altocumulus – a mid-level cumulus cloud Altostratus – a mid-level stratus cloud Strato/Stratus – Nearly all low level clouds are stratus clouds. Ex: stratus, stratocumulus, nimbostratus

4. High Level Clouds Cirrus Cirrus – the most common of the high cloud group. They are composed of ice crystals and look like long, thin wispy clouds. They predict fair weather. Prefix “Cirro” (Cirrus) means clouds made of ice crystals. Since all high altitude clouds are made of ice, they all have the prefix “Cirro”. Click images to enlarge CirrocumulusCirrocumulus – small rounded puffs that usually appear in long rows, usually white but sometimes gray. Can look like the scales of a fish. They generally appear in winter and indicate fair but cold weather. Cirrostratus Cirrostratus – sheet-like thin clouds that usually cover the entire sky. Usually come 24 hours before a rain or snow storm.

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6. Cirrocumulus cloud BACK

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8. Middle Clouds Prefix “Alto” means ‘mid-level clouds’. They exist between 2000m and 7000m above the ground, with a mix of ice crystals and water droplets. They usually predict bad weather coming. Altocumulus Altocumulus – they are grayish white, with one part of the cloud darker than the other. They usually form in groups and are generally about 1km thick. If you see altocumulus clouds on a warm, humid morning, expect thundershowers to come. Click images to enlarge Altostratus Altostratus – sheet-like thin clouds that cover the entire sky with a gray or blue-gray appearance. They usually form ahead of storms that have continuous rain or snow

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11. Low Clouds Nearly all low clouds are some form of stratus cloud. Low clouds consist of water droplets Stratus Stratus – they are uniform gray in colour and cover all of the sky. They look like fog. They are associated with light mist and drizzle. Click images to enlarge Stratocumulus Stratocumulus – they are low, lumpy and gray. They only give light precipitation or drizzle. Nimbostratus Nimbostratus – they are dark gray with a ragged base, and are usually associated with continual rain or snow. They cover the whole sky.

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13. Stratocumulus

14. Nimbostratus

15. Clouds with Vertical Growth Some cloud types can exist at any altitude, or are large enough to pass through multiple altitudes. They consist of a mixture of water droplets (at lower altitudes) and ice crystals (at higher altitudes). Cumulus Cumulus – puffy white clouds that look like floating cotton balls. Have sharp outlines and a flat base. Cumulus clouds can be associated with good or bad weather. Small cumulus clouds mean good weather; larger cumulus clouds are in the last stage of becoming stormy cumulonimbus clouds. Click images to enlarge Cumulonimbus Cumulonimbus – can grow as large as 10km high, and have an “anvil-shaped” top. Associated with heavy rain, snow, hail, lightning and tornadoes.

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