Editing Altocumulus cloud (section)

==Subtypes==
[[File:Midcloudcymbols.gif|thumb|300px|Middle cloud weather map symbols: Includes middle-étage and downward growing vertical.]]
:*Species:  Altocumulus has four species.  The [[Altocumulus stratiformis|stratiformis]] species (Ac str) is composed of sheets or relatively flat patches of stratocumuliform cloud.  The synoptic coding is determined by the predominant variety or occasionally by the genitus mother cloud. Altocumulus lenticularis (Ac len [[lenticular cloud]]) is a lens-shaped middle cloud which can resemble flying saucers and may occasionally be mistaken for "[[unidentified flying object]]s". This is formed by uplift usually associated with mountains. but usually with at least some grey shading. It is coded C<sub>M</sub>4 on the SYNOP weather observation. Grey shading is also seen with [[altocumulus castellanus]] (Ac cas), a turreted middle cloud that can achieve significant vertical development and signals increasing air mass instability. It is nevertheless usually classified as middle rather than vertical and is coded C<sub>M</sub>8. The [[Altocumulus floccus|floccus]] species (Ac flo) is a tufted middle cloud which is also associated with greater instability. It shares the same code C<sub>M</sub>8. Chaotic altocumulus, which is typically poorly defined with multiple species or transitional forms arranged in several layers,<ref name="Species">{{cite book|editor=World Meteorological Organization|editor-link=World Meteorological Organization|title=Species, International Cloud Atlas|volume=I|year=1975|url=https://archive.org/details/manualonobservat00worl/page/17|pages=[https://archive.org/details/manualonobservat00worl/page/17 17–20]|isbn=92-63-10407-7|access-date=26 August 2014}}</ref> is coded C<sub>M</sub>9.
::*Opacity-based varieties:  Altocumulus stratiformis has three opacity-based varieties; ''Translucidus'' (C<sub>M</sub>3), ''perlucidus'' (C<sub>M</sub>3 or 7 depending on predominant opacity), and ''opacus'' (C<sub>M</sub>7). Varieties based on opacity are not commonly associated with the species lenticularis, castellanus, or floccus.
::*Pattern-based varieties: ''Radiatus'' (arranged in parallel bands) is sometimes seen with the stratformis and castellanus species.  Altocumulus stratiformis radiatus of any opacity is coded C<sub>M</sub>5 if it is increasing in amount.  The ''duplicatus'' or ''undulatus'' varieties are occasionally seen with the stratiformis and lenticularis species.<ref name="Varieties">{{cite book |editor=World Meteorological Organization |title=Varieties, International Cloud Atlas |year=1975 |url=http://library.wmo.int/pmb_ged/wmo_407_en-v1.pdf |pages=20–22 |access-date=26 August 2014 |archive-url=https://web.archive.org/web/20160725172359/http://library.wmo.int/pmb_ged/wmo_407_en-v1.pdf |archive-date=25 July 2016 |url-status=dead }}</ref>  Altocumulus stratiformis duplicatus is coded C<sub>M</sub>7 if it is not overridden by another coding of higher importance.  ''Lacunosus'' is very occasionally associated with altocumulus of the species stratiformis, castellanus, or floccus.
:::*Precipitation-based supplementary feature: Altocumulus often produces virga but usually not precipitation that reaches the ground.
:::*Cloud-based supplementary feature: Mamma caused by localized downdrafts in the cloud layer are occasionally seen with altocumulus.<ref name="Features">{{cite book|editor=World Meteorological Organization|editor-link=World Meteorological Organization|title=Features, International Cloud Atlas|volume=I|year=1975|url=https://archive.org/details/manualonobservat00worl/page/22|pages=[https://archive.org/details/manualonobservat00worl/page/22 22–24]|isbn=92-63-10407-7|access-date=26 August 2014}}</ref> A newly recognized type is the asperitas feature that is characterized by chaotic undulations caused by severe wind shear.

:::*Genitus Mother clouds: Altocumulus stratiformis cumulogenitus or cumulonimbogenitus can form when the middle or upper part of a towering free convective cloud begins to spread horizontally due to a loss of convective lift.  It is coded C<sub>M</sub>6.
:::*Mutatus mother clouds: Altocumulus can form due to the complete transformation of cirrocumulus, altostratus, nimbostratus, or stratocumulus.