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Cloud Types
Clouds are classified by their height in the
atmosphere and appearance
and form at three height layers:
High Level Clouds form at 16,000 - 45,000 ft (5 - 13 km) - Cirro Prefix,
Mid Level Clouds form at 7,000 - 25,000 ft (2 - 8 km) - Alto Prefix,
Low Level Clouds form at land surface - 7,000 ft (0 - 2 km)
Clouds are also classifed by appearance
containing the following words:
Cirrus - wispy and thin. Cumulus - Puffy appearance. Stratus - Flat and/or layered.
Nimbus - Contain Precipitation.
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Cirrus (Ci)
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Cirrus are high clouds which are composed of ice cystrals that
originate from the freezing of supercooled water droplets. They are thin and have a wispy appearance, and are often
transparent. Usually indicates a change in weather will occur within 24 hours.
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Cirrocumulus (Cc)
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Cirrocumulus are high clouds,
composed of ice crystals. They appear as small individual cloudlets in rows. No shading can be seen
on the lower surface. Usually indicate fair weather for the near future.
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Cirrostratus (Cs)
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Cirrostratus are high clouds, composed of Ice Crystals.
Thin and uniform appearance, often covering the whole sky. A halo of
the sun or moon can usually be seen through the cloud. Usually indicate rain or snow within the next 12 - 24 hours.
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Altocumulus (Ac)
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Altocumulus, sometimes referred to as 'mackerel sky' because of the resemblance to the markings found on mackerel fish, are Mid level clouds composed of water droplets.
Similar to Cirrocumulus, but have larger individual cloudlets, and
shading can be seen. If seen in the morning, prepare for a thunderstorm in the afternoon.
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Altostratus (As)
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Altostratus clouds are mid level clouds composed of ice crystals and
water droplets. Generally uniform and grey in appearance, and frequently cover the
entire sky. The sun or moon may also be seen through them, but is
usually quite fuzzy. Tend to indicate a storm some time in the very near future.
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Stratocumulus (Sc)
Stratocumulus clouds are low level clouds composed of water droplets.
They
appear as low patches or sheets of grey to white cloud, with
individual rolls or rounded masses and do not usually bring
precipitation.
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Stratus (St)
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Stratus clouds are low level clouds composed of water droplets.
They appear as a uniform greyish layer and often cover the entire sky.
They can sometimes cover hill tops. Often bring drizzle or light snow.
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Nimbostratus (Ns)
Nimbostratus clouds are low level clouds that might consist entirely
of cloud droplets or raindrops, or of ice crystals and snowflakes. They are thick grey clouds with a ragged base. Sometimes they cover
the entire sky. Indicate rain in the very near future.
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Cumulus (Cu)
Cumulus clouds are low level clouds, composed of water droplets.
They are have a puffy appearence, a flat base and are white or light
grey. Indicate fair weather unless they grow vertically.
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Vertically Developed Clouds |
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Cumulonimbus (Cb)
Cumulonimbus clouds are Vertically Developed Clouds which are
composed of water droplets and ice crystals. Appear dark and very tall often extending through all the levels of
altitude, and can be several miles wide. They often appear in a shape
similar to a mushroom. Usually indicate a storm in the near future. Rain, hail, thunder,
lightning.
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