Cloud Formations Cloud formations have always been observed by people, many centuries before our time. People were always fond of clouds. They always wondered why some clouds were dark and others were white and fluffy, and why some clouds are so up high and others were so low that they looked reachable by the human hands. The most recent classification of clouds was accomplished by the World Meteorological Organization in 1956. This organization lists 10 basic kinds of clouds that are subdivided into species according to their outer shape and inner structure. In addition, cloud varieties are discussed according to arrangement an