Nimbostratus cloud
Under Luke Howard's first systematized study of clouds, carried out in France in 1802, three general cloud "forms" were established based on appearance and characteristics of formation: "cirriform," "cumiliform" and "stratiform." These were further divided into upper and lower types depending on altitude. In addition to these three main types, Howard added two names to designate multiple cloud types joined together: "cumulostratus," a blending of cumulus clouds and stratus layers, and "nimbus," a complex blending of cirriform, cumuliform, and stratiform clouds with sufficient vertical development to produce significant precipitation.
List of cloud types
The supplementary features are associated with particular genera as follows. They are sorted from left to right in approximate decreasing order of frequency of occurrence for each of three categories. The genus types (including some cumulus sub-types) are arranged from top to bottom in approximate descending order of average overall altitude range.
The possible combinations of genera and mother clouds can be seen in this table. The genitus and mutatus clouds are each sorted from left to right in alphabetical order. The genus types (including some cumulus sub-types) are arranged from top to bottom in the left column in approximate descending order of average overall altitude range.