Arcus clouds are low-level, wide ranging clouds typically associated with powerful storm clouds and thunderstorms.
Height of base: up to 6500 ft
Arcus comes from the latin word for arch . There are two types of arcus clouds: shelf clouds or roll clouds. They can normally be seen beneath powerful storm clouds or cumulonimbus clouds. Shelf clouds are wedge shaped and attached to the storm cloud whereas roll clouds are a horizontal column separated from the storm cloud that can appear to be rolling. They form within warm air from near the ground which has been pushed up by the cold air exiting out of the storm cloud in the downdraft.
The images below have been sent in by Met Office Twitter followers.
Last updated: Feb 17, 2017 11:33 AM
When rain falls from a cloud but doesn’t reach the ground it can create wispy tails from clouds known as virga.
The classification of clouds into types was first proposed by Luke Howard in 1802 and we largely use the same system today splitting clouds into three main types – stratus, cumulus and cirrus.
Use our cloud spotting guide and video to help identify different types of clouds in the sky.
Mammatus clouds are some of the most unusual and distinctive clouds formations with a series of bulges or pouches emerging from the base of a cloud.
Noctilucent clouds are extremely rare very high clouds seen in the night sky, usually on clear, summer nights.
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