no varieties, and nimbostratus that has no species or varieties. The boxes for genus and species combinations that have no varieties are left blank. WMO supplementary features Precipitation-based supplementary features Praecipitatio Latin for "falling": Cloud whose precipitation reaches the ground. Virga "Twig" or "branch": Cloud whose precipitation evaporates before reaching the ground. Cloud-based supplementary features Arcus Latin for "arch" or "bow": Feature mostly attached to cumulus, thick with ragged edges. Asperitas "Roughness": A highly disturbed and chaotic wave feature occasionally seen with a stratocumulus or altocumulus cloud. Cavum "Hole": Supercooled altocumulus or cirrocumulus distinguished by a hole with ragged edges and virga or wisps of cirrus. Cauda "Tail": A tail cloud that extends horizontally away from the murus cloud and is the result of air feeding into the storm. Fluctus Crested wave-like stratocumulus, altocumulus, or cirrus cloud formed by wind-shear. Incus "Anvil": Top part of a mature cumulonimbus cloud; anvil-shaped feature. Mammatus WMO term mamma: "Breast": A feature in the form of round pouches on under-surface of a cloud. Murus "Wall": Cumulonimbus wall cloud with a lowering rotating base that can portend tornadoes. Tuba "Funnel" or "tube": Feature in the form of a column hanging from the bottom of cumulus or cumulonimbus. Accessory clouds Pannus Latin for "shredded cloth": A ragged or shredded accessory cloud that forms in precipitation below the main cloud. Pileus "Capped": A hood-shaped accessory cloud. Velum "A ship's sail": An accessory cloud in the form of a sail. The supplementary features are associated with particular genera as follows. They are sorted from left to right in approximate decreasing order of frequency of occurrence for each of three categories. The genus types and some sub-types are arranged from top to bottom in approximate descending order of average overall altitude range. Each box is marked where a particular genus or sub-type has a particular supplementary feature. Genitus mother clouds Altocumulogenitus Formed by the partial transformation of altocumulus mother cloud. Altostratogenitus Formed by the partial transformation of altostratus. Cirrogenitus Partial transformation of cirrus. Cirrocumulogenitus Partial transformation of cirrocumulus. Cirrostratogenitus Partial transformation of cirrostratus. Cumulogenitus Spreading out or partial transformation of cumulus. Cumulonimbogenitus Spreading out or partial transformation of cumulonimbus. Nimbostratogenitus Partial transformation of nimbostratus. Stratogenitus Partial transformation of stratus. Stratocumulogenitus Partial transformation of stratocumulus. Other genitus clouds Cataractagenitus (cataracta-/pertaining to a river cataract) Formed from the mist at a waterfall, the downdraft caused from the cloud is counteracted by