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 first cloud formation added since cirrus intortus in 1951.[2]#citenote-geo-2) The name translates approximately as "roughness" .[[3]](https://en.wikipedia.org/wiki/Asperitas(cloud)#cite_note-guard-3)