Accessory cloud types can form at various altitude ranges depending on the main clouds with which they are associated. The World Meteorological Organization classifies most accessory clouds as "supplementary features". The height range classification of a supplementary feature is the same as the parent cloud. As an example, the anvil cloud (supplementary feature incus) forms at high altitude but is not classified by the WMO as a high cloud because of its association with the genus cumulonimbus. It is "very rare" for any accessory cloud to generate its own precipitation. However, the parent cloud may generate precipitation. Precipitation from the parent cloud
Cirrostratus cloud below cirrostratus formations, due to the stable air associated with cirrostratus creating an inversion and restricting convection, causing cumuliform clouds to become flattened. Contrails also tend to spread out and can be visible for up to an hour in cirrostratus. The phrase "milky sunshine" is often, as well as referring to haze or light mist, used to refer to the milky look of the sky when cirrostratus is present. Cirrostratus cloud Cirrostratus is a high-level, very thin, generally uniform "stratiform" genus-type of cloud, composed of ice-crystals. It is difficult to detect and is capable of forming halos when the cloud