cloud) – shredded sections attached to main Cb cloud. Cumulonimbus pileus (WMO genus and accessory cloud) – capped, hood-shaped cloud above a cumulonimbus cloud. Cumulonimbus praecipitatio (WMO genus and supplementary feature) – Cb whose precipitation reaches the ground. Cumulonimbus tuba (WMO genus and supplementary feature) – column hanging from the bottom of cumulonimbus. Debris cloud (informal term) – rotating "cloud" of debris found at base of tornado. Funnel cloud (WMO supplementary feature tuba) – rotating funnel of cloud hanging from under Cb, not making contact with ground. Hail fog (informal term) – a shallow surface layer of fog that sometimes forms in vicinity of deep hail accumulation, can be very dense. Hot tower (informal term) – a tropical cumulonimbus cloud that penetrates the tropopause. Inflow band (informal term) – a laminar band marking inflow to a Cb, can occur at lower or mid levels of the cloud. Inverted cumulus (informal variation of WMO supplementary feature mamma) – cumulus which has transferred momentum from an exceptionally intense Cb tower and is convectively growing on the underside of an anvil. Knuckles (informal variation of WMO supplementary feature mamma) – lumpy protrusion that hangs from edge or underside of anvil. Pyrocumulus and Pyrocumulonimbus– intense ground-heat cloud proposed for WMO classification (see above). Rope – (slang) narrow, sometimes twisted funnel type cloud seen after a tornado dissipates. Rope cloud (informal term) – A narrow, long, elongated line of cumulus clouds that sometimes develop at the leading edge of an advancing cold front that is often visible in satellite imagery. Scud cloud (informal term for WMO species fractus) – ragged detached portions of cloud that usually form in precipitation. Shelf cloud (informal term for WMO supplementary feature arcus) – wedge-shaped cloud often attached to the underside of Cb. Stratus fractus (WMO genus and species) – ragged detached portions of stratus cloud that usually form in precipitation (see also scud cloud). Striations (informal term for WMO accessory cloud velum) – a groove or band of clouds encircling an updraft tower, indicative of rotation. Tail cloud (informal term) – an area of condensation consisting of laminar band and cloud tags extending from a wall cloud towards a precipitation core. Towering cumulus (TCu) -aviation term for WMO genus and species cumulus congestus, a large cumulus cloud with great vertical development, usually with a cauliflower-like appearance, but lacking the characteristic anvil of a Cb. Wall cloud (informal term) –