Cloud classification symbol CL9. Cumulonimbus, the upper part of which is clearly fibrous (cirriform) often in the form of an anvil; either accompanied or not by cumulonimbus without anvil or fibrous upper part, by cumulus, stratocumulus, stratus or 'scud' (Cumulonimbus cappillatus or incus).
NOAA
2008-04-18
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