Editing Cloud (section)

===Species===

Genus types are commonly divided into subtypes called ''species'' that indicate specific structural details which can vary according to the stability and windshear characteristics of the atmosphere at any given time and location. Despite this hierarchy, a particular species may be a subtype of more than one genus, especially if the genera are of the same physical form and are differentiated from each other mainly by altitude or level. There are a few species, each of which can be associated with genera of more than one physical form.<ref name="species">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Species, International Cloud Atlas |url=https://cloudatlas.wmo.int/principles-of-cloud-classification-species.html |access-date=2 June 2017}}</ref> The species types are grouped below according to the physical forms and genera with which each is normally associated. The forms, genera, and species are listed from left to right in approximate ascending order of instability or convective activity.<ref name="meteorology" />

{| class="wikitable"
!Forms and levels !! Stratiform <br> non-convective !! Cirriform <br> mostly nonconvective !! Stratocumuliform <br> limited-convective !! Cumuliform <br> free-convective !! Cumulonimbiform <br> strong convective
|-
!High-level
| [[Cirrostratus]]{{blist| nebulosus| fibratus }}||[[Cirrus cloud|Cirrus]]<br> '''non-convective'''{{blist| uncinus| fibratus| spissatus}} '''limited convective'''{{blist| castellanus| floccus}} || [[Cirrocumulus]]{{blist| stratiformis| lenticularis| castellanus| floccus}}|| ||
|-
!Mid-level
| [[Altostratus]]{{blist| no differentiated species<br>(always nebulous)}} || || [[Altocumulus]]{{blist| stratiformis| lenticularis|  castellanus| floccus| volutus}}||
|-
!Low-level
| [[Stratus cloud|Stratus]]{{blist| nebulosus| [[fractus]]}}|| || [[Stratocumulus]]{{blist| stratiformis| lenticularis| castellanus| floccus| volutus}}|| [[Cumulus]]{{blist| [[Cumulus humilis|humilis]]| [[fractus]]}}  ||
|-
!Multi-level or moderate vertical
| [[Nimbostratus]]{{blist| no differentiated species<br>(always nebulous)}} || || || Cumulus{{blist| [[Cumulus mediocris|mediocris]]}} ||
|-
!Towering vertical
| || || || Cumulus{{blist| [[Cumulus congestus|congestus]] || [[Cumulonimbus]]{{blist| calvus| capillatus}}
|-
|}

====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" />

====Ragged====
The species ''fractus'' shows ''variable'' instability because it can be a subdivision of genus-types of different physical forms that have different stability characteristics. This subtype can be in the form of ragged but mostly ''stable'' stratiform sheets (stratus fractus) or small ragged cumuliform heaps with somewhat greater instability (cumulus fractus).<ref name="species" /><ref name="clouds - species and varieties" /><ref name="fractus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Species Fractus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-fractus.html |access-date=5 April 2018}}</ref> When clouds of this species are associated with precipitating cloud systems of considerable vertical and sometimes horizontal extent, they are also classified as ''accessory clouds'' under the name ''pannus'' (see section on supplementary features).<ref name="pannus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Accessory Cloud Pannus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-accessory-pannus.html |access-date=5 April 2018}}</ref>

====Partly unstable====
[[File:Stratocumulus castellanus 3oct.jpg|thumb|Example of a castellanus cloud formation]]
These species are subdivisions of genus types that can occur in partly unstable air with limited [[convection]]. The species ''castellanus'' appears when a mostly stable stratocumuliform or cirriform layer becomes disturbed by localized areas of airmass instability, usually in the morning or afternoon. This results in the formation of embedded cumuliform buildups arising from a common stratiform base.<ref name="Elevated convection">{{Cite journal |last1=Stephen F. Corfidi |last2=Sarah J. Corfidi |last3=David M Schultz |year=2008 |title=Elevated Convection and Castellanus: Ambiguities, Significance, and Questions |url=https://zenodo.org/record/1234533 |journal=Weather and Forecasting |volume=23 |issue=6 |page=1282 |bibcode=2008WtFor..23.1280C |doi=10.1175/2008WAF2222118.1|doi-access=free }}</ref> Castellanus resembles the turrets of a castle when viewed from the side, and can be found with stratocumuliform genera at any tropospheric altitude level and with limited-convective patches of high-level cirrus.<ref name="species-castellanus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Species Castellanus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-castellanus.html |access-date=5 April 2018}}</ref> Tufted clouds of the more detached ''floccus'' species are subdivisions of genus-types which may be cirriform or stratocumuliform in overall structure. They are sometimes seen with cirrus, cirrocumulus, altocumulus, and stratocumulus.<ref name="floccus">{{Cite web |year=2017 |editor-last=World Meteorological Organization |title=Species Floccus, International Cloud Atlas |url=https://cloudatlas.wmo.int/clouds-species-floccus.html |access-date=5 April 2018}}</ref>

A newly recognized species of stratocumulus or altocumulus has been given the name ''volutus'', a roll cloud that can occur ahead of a cumulonimbus formation.<ref name="ICA2017">{{Cite news |last=Sutherland |first=Scott |date=23 March 2017 |title=Cloud Atlas leaps into 21st century with 12 new cloud types |work=The Weather Network |agency=Pelmorex Media |url=https://www.theweathernetwork.com/news/articles/cloud-atlas-leaps-into-21st-century-with-12-new-cloud-types/80685/ |access-date=24 March 2017 |archive-date=31 May 2022 |archive-url=https://web.archive.org/web/20220531022305/https://www.theweathernetwork.com/news/articles/cloud-atlas-leaps-into-21st-century-with-12-new-cloud-types/80685/ |url-status=dead }}</ref> There are some volutus clouds that form as a consequence of interactions with specific geographical features rather than with a parent cloud. Perhaps the strangest geographically specific cloud of this type is the [[Morning Glory cloud|Morning Glory]], a rolling cylindrical cloud that appears unpredictably over the [[Gulf of Carpentaria]] in [[Northern Australia]]. Associated with a powerful "ripple" in the atmosphere, the cloud may be "surfed" in [[Glider (sailplane)|glider]] aircraft.<ref name="stg">{{Cite web |last=Abbie Thomas |date=7 August 2003 |title=Soaring the glory |url=http://www.abc.net.au/science/articles/2003/08/07/2045486.htm |access-date=30 August 2014 |website=ABC Science |publisher=Australian Broadcasting Corporation}}</ref>

====Unstable or mostly unstable====
More general airmass instability in the troposphere tends to produce clouds of the more freely convective cumulus genus type, whose species are mainly indicators of degrees of atmospheric instability and resultant vertical development of the clouds. A cumulus cloud initially forms in the low level of the troposphere as a cloudlet of the species ''humilis'' that shows only slight vertical development. If the air becomes more unstable, the cloud tends to grow vertically into the species ''mediocris'', then strongly convective ''congestus'', the tallest cumulus species<ref name="species" /> which is the same type that the International Civil Aviation Organization refers to as 'towering cumulus'.<ref name="automated Cb and Tcu detection" />

[[File:Cumulus mediocris atmospheric instability 01.jpg|thumb|Cumulus mediocris cloud, about to turn into a cumulus congestus]]
With highly unstable atmospheric conditions, large cumulus may continue to grow into even more strongly convective cumulonimbus ''calvus'' (essentially a very tall congestus cloud that produces thunder), then ultimately into the species ''capillatus'' when supercooled water droplets at the top of the cloud turn into ice crystals giving it a cirriform appearance.<ref name="species" /><ref name="clouds - species and varieties">{{Cite web |last=Boyd, Sylke |year=2008 |title=Clouds – Species and Varieties |url=http://www.morris.umn.edu/~sboyd/weather/cloudsystems/Clouds_files/speciesandvarieties.htm |url-status=dead |archive-url=https://web.archive.org/web/20101230041442/http://www.morris.umn.edu/~sboyd/weather/cloudsystems/Clouds_files/speciesandvarieties.htm |archive-date=30 December 2010 |access-date=4 February 2012 |website=University of Minnesota}}</ref>