Tuesday, August 19, 2014

Cloud names and classifications

Cloud names and classifications

cloud altitude chart

Cloud spotting
Clouds are continually changing and appear in an infinite variety of forms. This is a guide to the 10 main named groups of clouds.
Clouds are continually changing and appear in an infinite variety of forms. The classification of clouds is based on a book written by Luke Howard, a London pharmacist and amateur meteorologist, in 1803. His book, The Modifications of Clouds, named the various cloud structures he had studied. The terms he used were readily accepted by the meteorological community and are still used across the world today.
The World Meteorological Organization (WMO) has extended Luke Howard's classifications to make 10 main groups of clouds, called genera. These are divided into three levels - cloud low (CL), cloud medium (CM) and cloud high (CH) - according to the part of the atmosphere in which they are usually found.
The many possibly variations in the shape of clouds and differences in their internal structure have led to the subdivision of most of the cloud genera into species. For a more detailed guide on cloud spotting including species and cloud codes, view our Cloud types for observers Cloud types for observers(PDF, 4 MB)  guide.
The names for clouds are usually are combinations of the following prefixes or suffixes:
Stratus/strato = flat/layered and smooth
Cumulus/cumulo = heaped up/puffy, like cauliflower
Cirrus/cirro = High up/wispy
Alto = Medium level
Nimbus/Nimbo = Rain-bearing cloud

Cloud families and other cloud pictures/appearances
In meteorology we divide clouds in 4 clouds families, which are in different heights of the troposphere: High level clouds (altitudes of 5-13 km), medium level clouds (2-7 km), low level clouds (0-2 km) and clouds with large vertical extending (0-13 km).
These clouds families are divided in 10 cloud genus:

Cloud names and classifications
Cloud names and classifications

Cloud level (ft)Cloud type
High clouds (CH)
Base usually 20,000 ft or above, over British Isles
Medium clouds (CM)
Base usually between 6,500 and 20,000 ft over British Isles.
Low clouds (CL)
Base usually below 6,500 ft over British Isles.

Names for clouds :Click on pic of each cloud for more details and pictures:

High level clouds at heights of 5-13 km
Fibrous, threadlike, white feather clouds of ice crystals, whose form resembles hair curls.
Milky, translucent cloud veil of ice crystals, which sometimes causes halo appearances around moon and sun.
CirrocumulusCcFleecy cloud; Cloud banks of small, white flakes.
Medium level clouds at heights of 2-7 km
AltocumulusAcGrey cloud bundles, sheds or rollers, compound like rough fleecy cloud, which are often arranged in banks.
AltostratusAsDense, gray layer cloud, often evenly and opaquely, which lets the sun shine through only a little.
Low level clouds at heights of 0-2 km
StratocumulusScCloud plaices, rollers or banks compound dark gray layer cloud.
StratusStEvenly grey, low layer cloud, which causes fog or fine precipitation and is sometimes frazzled.
Clouds with large vertical extending at heights of 0-13 km
Heap cloud with flat basis in the middle or lower level, whose vertical development reminds of the form of towers, cauliflower or cotton.
CumulonimbusCbIn the middle or lower level developing thundercloud, which mostly up-rises into the upper level.
NimbostratusNsRain cloud. Grey, dark layer cloud, indistinct outlines.
Other cloud pictures and appearances
other cloud photosThese photos are not assigned to individual cloud families, because they e.g. show a chaotic sky with many different cloud types or undefinite photos.
other appearancesAppearances, which fit into no other classification

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