Altocumulus floccus

Type of cloud
Altocumulus floccus
Altocumulus floccus over Germany in October 2010
AbbreviationAc flo
GenusAltocumulus (high, heaped)
Speciesfloccus
Altitude2,000–6,000 m
(6,500–20,000 ft)
ClassificationFamily B (Medium-level)
AppearanceOften present in diffuse patches; whitish or dark, and the bases are sometimes not all at the same level.
PrecipitationVirga only.

Altocumulus floccus is a cloud type named for its tuft-like, wooly appearance.[1] The base of the cloud can form as low as 2,000 metres (6,600 ft), or as high as 6,000 metres (20,000 ft). They often form in clusters, or patches, and bases can vary in height with differing atmospheric conditions within the PBL.[2] They are similar to Altocumulus castellanus, but often have a shallower vertical extent in comparison.[3]

Floccus clouds form when in the presence of conditional, often shallow, mid-level instability. On some occasions, such as the presence of a deeper unstable layer, these clouds can grow large enough to develop into thunderstorms.[4]

References

  1. ^ Houze, Jr., Robert A. (1994). Cloud Dynamics. Ukraine: Elsevier Science. p. 15. ISBN 9780080502106. Retrieved 27 August 2021. Altocumulus floccus (meaning tuft of wool, fluff, or nap of cloth...)
  2. ^ "Altocumulus floccus". International Cloud Atlas.
  3. ^ "Altocumulus floccus (Ac flo)".
  4. ^ "Altocumulus floccus". Weather Briefing, L.C. 18 May 2019.
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Cloud genera and selected species, supplementary features, and other airborne hydrometeors - WMO Latin terminology except where indicated
Mesospheric
Extreme-level
80–85 km
Noctilucent (NLC)
Polar mesospheric clouds
  • Noctilucent type I veils
  • Noctilucent type II bands
  • Noctilucent type III billows
  • Noctilucent type IV whirls
Stratospheric
Very high-level
15–30 km
Nacreous polar stratospheric clouds (PSC)
  • Cirriform nacreous
  • Lenticular nacreous
Nitric acid and water
polar stratospheric clouds (PSC)
  • No differentiated sub-types; tends to resemble cirrostratus
Tropospheric
High-level
3–18 km
Cirrus (Ci)
Species
Ci-only varieties
Cirrocumulus (Cc)
Species
Cirrostratus (Cs)
Species
High-level-only
mutatus cloud
  • Mutatus non-height specific (see below)
Medium-level
2–8 km
Altocumulus (Ac)
Species
Altostratus (As)
Nimbostratus (Ns)
Multi-level
Varieties
Low-level
0–2 km
Cumulonimbus (Cb)
Towering vertical
Species
Cb-only supplementary features
Cb-only accessories and other
Cumulus (Cu)
Variable vertical extent
Species
Other
Stratus (St)
Species
St-only genitus cloud and other
Stratocumulus (Sc)
Species
Low-level-only
supplementary features
Low-level-only
accessory cloud and other
Non-height
specific
Varieties
Supplementary features
Mother clouds
and human-made clouds
  • (Mother cloud)+genitus (e.g. cumulogenitus (cugen)
  • (Mother cloud)+mutatus (e.g. cumulomutatus (cumut)
  • Homogenitus (hogen)
  • Homomutatus (homut)
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