Editing Cloud (section)

====Stable or mostly stable====
Of the non-convective stratiform group, high-level cirrostratus comprises two species. Cirrostratus ''nebulosus'' has a rather diffuse appearance lacking in structural detail.<ref name="nebulosus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Nebulosus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-nebulosus.html |access-date=2 June 2017}}</ref> Cirrostratus ''fibratus'' is a species made of semi-merged filaments that are transitional to or from cirrus.<ref name="fibratus" /> Mid-level altostratus and multi-level nimbostratus always have a flat or diffuse appearance and are therefore not subdivided into species. Low stratus is of the species nebulosus<ref name="nebulosus" /> except when broken up into ragged sheets of stratus [[fractus]] (see below).<ref name="cloud atlas" /><ref name="species" /><ref name="clouds - species and varieties" />

Cirriform clouds have three non-convective species that can form in ''stable'' airmass conditions. Cirrus fibratus comprise filaments that may be straight, wavy, or occasionally twisted by wind shear.<ref name="fibratus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Fibratus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-fibratus.html |access-date=2 June 2017}}</ref> The species ''uncinus'' is similar but has upturned hooks at the ends. Cirrus ''spissatus'' appear as opaque patches that can show light gray shading.<ref name="species" />

[[File:Lenticular Cloud in Wyoming 0034b.jpg|thumb|[[Lenticular cloud|Altocumulus lenticularis]] forming over mountains in Wyoming with lower layer of cumulus mediocris and higher layer of cirrus spissatus]]

Stratocumuliform genus-types (cirrocumulus, altocumulus, and stratocumulus) that appear in mostly stable air with limited convection have two species each. The ''stratiformis'' species normally occur in extensive sheets or in smaller patches where there is only minimal convective activity.<ref name="stratiformis">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Stratiformis, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-stratiformis.html |access-date=2 June 2017}}</ref> Clouds of the ''lenticularis'' species tend to have lens-like shapes tapered at the ends. They are most commonly seen as orographic mountain-[[wave cloud]]s, but can occur anywhere in the troposphere where there is strong wind shear combined with sufficient airmass stability to maintain a generally flat cloud structure. These two species can be found in the high, middle, or low levels of the troposphere depending on the stratocumuliform genus or genera present at any given time.<ref name="cloud atlas" /><ref name="species" /><ref name="clouds - species and varieties" />