An updated version of the World Meteorological Association's International Cloud Atlas includes several newly discovered clouds, including a formation called 'asperitas'.

Asperitas clouds spotted in north Dorset, England. (Jo Adams/Cloud Appreciation Society)

The new cloud was first observed by an amateur cloudspotter in Cedar Rapids, Iowa, in 2006 and brought to the attention of the UK based Cloud Appreciation Society.

Asperitas was turning up in photos from around the world, which prompted CAS founder Gavin Pretor-Pinney to convince the WMS that it should be included in their new on-line atlas. Asperitas, the Latin word for roughness, has always been around. Asperitas is described as an intense, chaotic wave-like formation.