Note from the editor:

This Atlas describes the classification system for clouds and meteorological phenomena used by all WMO Members. The classifications also describe meteorological meteors other than clouds – hydrometeors, lithometeors, photometeors, and electrometeors. The Atlas provides a common language to communicate cloud observations, and ensures consistency in reporting by observers around the world. It serves as a training tool for meteorologists, as well as for those working in aeronautical and maritime environments, and it has become popular with weather enthusiasts and cloud spotters.