Cloud level (ft)Cloud type
High clouds (CH)
Base usually 20,000 ft or above, over British Isles
CirrusCirrocumulusCirrostratusMedium clouds (CM)Base usually between 6,500 and 20,000 ft over British Isles.AltocumulusAltostratusNimbostratusLow clouds (CL)Base usually below 6,500 ft over British Isles.hope this helps!