Cloud atlas was published in 1802. It followed a similar effort in French by Jean-Baptiste Lamarck in 1801. Howard's nomenclature defined four fundamental types of clouds: cirrus or thread-cloud, cumulus or heap-cloud, stratus or flat cloud (level sheet), and nimbus or rain-cloud (see Classification of clouds). There followed a long period of development of the field of meteorology and the classification of clouds, leading up to 1896, the International Year of Clouds. The history of this period is the subject of a popular book, "The Invention of Clouds". During that time, the Englishmen Rev. Clement Ley and Hon. Ralph Abercromby, were influential.
Altocumulus cloud Altocumulus cloud Altocumulus (From Latin "Altus", "high", "cumulus", "heaped") is a middle-altitude cloud genus that belongs mainly to the "stratocumuliform" physical category characterized by globular masses or rolls in layers or patches, the individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus. However, if the layers become tufted in appearance due to increased airmass instability, then the altocumulus clouds become more purely "cumuliform" in structure. Like other cumuliform and stratocumuliform clouds, altocumulus signifies convection. A sheet of partially conjoined altocumulus perlucidus is sometimes found preceding a weakening warm front, where the altostratus is