Cloud names and classifications
Clouds are continually changing and appear in an infinite variety of forms. This is a guide to the 10 main named groups of clouds.
Clouds are continually changing and appear in an infinite variety of forms. The classification of clouds is based on a book written by Luke Howard, a London pharmacist and amateur meteorologist, in 1803. His book, The Modifications of Clouds, named the various cloud structures he had studied. The terms he used were readily accepted by the meteorological community and are still used across the world today.
The World Meteorological Organization (WMO) has extended Luke Howard's classifications to make 10 main groups of clouds, called genera. These are divided into three levels - cloud low (CL), cloud medium (CM) and cloud high (CH) - according to the part of the atmosphere in which they are usually found.
The many possibly variations in the shape of clouds and differences in their internal structure have led to the subdivision of most of the cloud genera into species. For a more detailed guide on cloud spotting including species and cloud codes, view our Cloud types for observers(PDF, 4 MB) guide.