Moderate to large cumuliform and cumulonimbiform heaps and deep stratiform layers that occupy more than one altitude range are usually classified as vertical or multi-�tage . cumulonimbus may form anywhere from near the surface to intermediate heights of around 3 kilometres.
22.
The genus types are arranged from top to bottom in the same ascending order for each �tage . ( 1 ) = Stratiform types, ( 2 ) = Cirriform types, ( 3 ) = Stratocumuliform types, ( 4 ) = Cumuliform types, ( 5 ) = Cumulonimbiform types.
23.
Rather than assuming that clouds form at 100 % relative humidity, the cloud fraction can be related to a critical relative humidity of 70 % for stratus-type clouds, and at or above 80 % for cumuliform clouds, reflecting the sub grid scale variation that would occur in the real world.
24.
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.
25.
These are, in approximate ascending order of instability or convective activity : " stratiform " sheets; " cirriform " wisps and patches; " stratocumuliform " patches, rolls, and ripples; " cumuliform " heaps and tufts, and " cumulonimbiform " towers that often have complex structures.
26.
These physical types, in approximate ascending order of convective activity, include " stratiform " sheets, " cirriform " wisps and patches, " stratocumuliform " layers ( mainly structured as rolls, ripples, and patches ), " cumuliform " heaps and tufts, and very large " cumulonimbiform " heaps that often show complex structure.
27.
After the pannus types, the remaining accessory clouds comprise formations that are associated mainly with upward-growing cumuliform and cumulonimbiform clouds of free convection . " Pileus " is a cap cloud that can form over a cumulonimbus or large cumulus cloud, whereas a " velum " feature is a thin horizontal sheet that sometimes forms like an apron around the middle or in front of the parent cloud.
28.
Additional proposals were made by Andre Poey ( 1863 ), Clemment Ley ( 1894 ), and H . H . Clayton ( 1896 ), but their systems, like earlier alternative schemes, differed too much from Howard's to have any success beyond the adoption of some secondary cloud types . and cumuliform ( with the later addition of cumulonimbiform ), eventually found favor as an aid in the analysis of satellite cloud images.
