On March 23, on the occasion of the World Meteorological Day, the World Meteorological Organization released the digitised International Cloud Atlas, which includes several new types of clouds, including Asperitas, which in Latin stands for “rough.”
The Atlas, which includes a manual of standards and photographs of clouds and weather phenomena, was first published in the 19th century. It was last updated 30 years ago.
The 2017 digitised version of the Atlas includes a dozen new additions, including the shortlived ”Fluctus”, which looks like a row of sea horses ready to take off and forms on the top surface of clouds. These are also known as Kelvin-Helmholtz waves. Another type is the ”Flammagenitus”, which forms as a result of convection arising from localised heat sources such as forest fires.