Accessory cloud

Wall cloud on the right under a cumulonimbus cloud

An accessory cloud is a cloud which is dependent on a larger cloud system for its development and continuance. It is often an appendage but also can be adjacent to the parent cloud system.[1]

The arcus and roll clouds, shelf cloud, wall cloud, and scud are examples of low level or vertical accessory clouds whilst the anvil, and overshooting top, are examples of high level accessory clouds. The condensation funnel of funnel clouds and tornadoes are also accessory clouds. They are associated with deep moist convection and especially cumulonimbus, the primary cloud producing thunderstorms. The pileus and mammatus types can form at various altitude ranges depending on the main clouds with which they are associated. The World Meteorological Organization classifies most accessory clouds as supplementary features. The height range classification of a supplementary feature is the same as the parent cloud. As an example, the anvil cloud (supplementary feature incus) forms at high altitude but is not classified by the WMO as a high cloud because of its association with the genus cumulonimbus.[2]

Precipitation

It is very rare for any accessory cloud to generate its own precipitation (except for wall clouds). However, the parent cloud may generate precipitation. Precipitation from the parent cloud is often confused with the accessory cloud and observers think that the precipitation is actually falling from the accessory cloud.[citation needed]

See also

References

  1. ^ Glickman, Todd S. (June 2000). Glossary of Meteorology. Boston: American Meteorological Society.
  2. ^ World Meteorological Organization (1995). "WMO cloud classifications" (PDF). Retrieved 2012-01-23.
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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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