A subdivision of cloud genera based upon the cloud shape or internal structure. Cloud species are:

calvus (cal) - tops smooth
capillatus (cap) - distinct icy regions with anvil or plume
castellanus (cas) - turrets connected by a common base, often in lines
congestus (con) - markedly growing, cauliflower-like tops
fibratus (fib) - nearly straight
floccus (flo) - small tufts with ragged lower portion
fractus (fra) - ragged shreds
humilis (hum) - flattened
lenticularis (len) - wave cloud, lens-shaped
mediocris (med) - moderate depth, tops with small bulges
nebulosus (neb) - thin undifferentiated veil
spissatus (spi) - dense enough to appear grey near the sun
stratiformis (str) - very extensive horizontal sheet
uncinus (unc) - comma or hook-shaped

The standard abbreviations consist of the first three letters. None, one or more ofthe terms may be applied to describe an individual cloud type (genus)

Related features:
Cloud classification
Cloud types (genera)
Cloud variety
Clouds - sentry of the sky