Cumulus congestus cloud (No official abbreviation) is a free convective cloud associated with volcanic eruptions and large-scale fires. Pyrocumulus isn't recognized by the WMO as a distinct genus or species, but is, in essence, cumulus congestus formed under special circumstances that can also cause severe turbulence. Cumulus congestus will mature into cumulonimbus calvus under conditions of sufficient instability. This transformation can be seen by the presence of smooth, fibrous, or striated aspects assumed by the cloud's upper part. This cloud type produces precipitation, often in abundance. These clouds also produce fair weather waterspouts. An approaching weather front often brings mid level clouds such
Asperitas (cloud) because sunlight illuminates the undulating clouds from the side. Since 2006, many similar cloud formations have been contributed to the gallery, and in 2009 Gavin Pretor-Pinney, founder of The Cloud Appreciation Society, began working with the Royal Meteorological Society to promote the cloud type as an entirely new type in and of itself. Asperitas (cloud) Asperitas (formerly known as Undulatus asperatus) is a cloud formation first popularized and proposed as a type of cloud in 2009 by Gavin Pretor-Pinney of the Cloud Appreciation Society. Added to the International Cloud Atlas as a supplementary feature in March 2017, it is the