nebulosus) producing precipitation. Accessory clouds Not usually seen with stratus. Genitus mother clouds and other mother sources Stratus nimbostratogenitus Stratus cumulogenitus Stratus cumulonimbogenitus Stratus cataractagenitus Generated by the spray from waterfalls. Stratus silvagenitus A stratus cloud that forms as water vapor is added to the air above a forest. Stratus homogenitus Mutatus mother cloud Stratus stratocumulomutatus Tropospheric cloud types with Latin etymologies where applicable Cloud types are sorted in alphabetical order except where noted. WMO genera Altocumulus (altus and cumulus) Latin for "high heap": Applied to mid-level stratocumuliform. Altostratus (altus and stratus) "High sheet": Applied to mid-level stratiform. Cirrocumulus (cirrus and cumulus) "Hair-like heap": Applied to high-level stratocumuliform. Cirrostratus (cirrus and stratus) "Hair-like sheet": Applied to high-level stratiform. Cirrus "Hair-like": Applied to high-level cirriform. Cumulonimbus (cumulus and nimbus) "Precipitation-bearing heap": Applied to vertical/multi-level cumulonimbiform. Cumulus "Heap": Applied to low-level and vertical/multi-level cumuliform. Nimbostratus (nimbus and stratus) "Precipitation-bearing sheet": Applied to multi-level stratiform with vertical extent that produces precipitation of significant intensity. Stratocumulus (stratus and cumulus) "Sheet-like heap": Applied to low-level stratocumuliform. Stratus "Sheet": Applied to low-level mostly shallow stratiform. WMO species Castellanus (Cas) Latin for "castle-like": Applies to stratocumuliform (Sc cas, Ac cas, Cc cas) and dense cirriform (Ci cas) with a series of turret shapes – indicates air mass instability. Congestus (Con) Latin for "congested": Applies to cumuliform (Cu con/Tcu) with great vertical development and heaped into cauliflower shapes – indicates considerable airmass instability and strong upcurrents. Fibratus (Fib) "Fibrous": Cirriform (Ci fib) or high stratiform (Cs fib) in the form of filaments, can be straight or slightly curved; indicates strong, continuous upper winds. Floccus (Flo) "Tufted": Applies to stratocumuliform (Sc flo, Ac flo, Cc flo) and high cirriform (Ci flo); indicates some mid or high-level instability. Fractus (Fra) "Broken": Low stratiform (St fra) or cumuliform (Cu fra) with an irregular shredded appearance – forms in precipitation and/or gusty winds. Humilis (Hum) "Small": Applies to cumuliform (Cu hum) with little vertical extent; indicates relatively slight airmass instability. Lenticularis (Len) "Lens–like": Stratocumuliform (Sc len, Ac len, Cc len) having a lens-like appearance – formed by standing waves of wind passing over mountains or hills. Mediocris (Med) "Medium-size": Cumuliform (Cu med) with moderate vertical extent; indicates moderate instability and upcurrents. Nebulosus (Neb) "Nebulous": Indistinct low and high stratiform (St neb, Cs neb) without features; indicates light wind if any and stable air mass. Spissatus (Spi) "Dense": Thick cirriform (Ci spi) with