Cumulus congestus clouds, also known as towering cumulus, are a form of

cumulus Cumulus clouds are clouds which have flat bases and are often described as "puffy", "cotton-like" or "fluffy" in appearance. Their name derives from the Latin ''cumulo-'', meaning ''heap'' or ''pile''. Cumulus clouds are low-level clouds, gener ...

that can be based in the low or middle height ranges. They achieve considerable vertical development in areas of deep, moist

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...

. They are an intermediate stage between

cumulus mediocris Cumulus mediocris is a low to middle level cloud with some vertical extent (Family D1) of the genus cumulus, larger in vertical development than Cumulus humilis. It also may exhibit small protuberances from the top and may show the cauliflower fo ...

and

cumulonimbus Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful Buoyancy, buoyant air ...

, sometimes producing showers of snow, rain, or

ice pellets Ice pellets are a form of precipitation consisting of small, hard, translucent balls of ice. Ice pellets are different from graupel ("soft hail") which is made of frosty white opaque rime, and from a mixture of rain and snow which is a slushy ...

. Precipitation that evaporates before reaching the surface is

virga In meteorology, a virga, also called a dry storm, is an observable :wikt:fallstreak, streak or Precipitation shaft, shaft of precipitation (meteorology), precipitation falling from a cloud that Evaporation, evaporates or Sublimation (phase t ...

Description

Cumulus congestus clouds are characteristic of unstable areas of the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

which are undergoing convection. They are often characterized by sharp outlines and great vertical development. Because they are produced by (and primarily composed of) strong

updraft In meteorology, an updraft is a small-scale current of rising air, often within a cloud. Overview Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding region, ...

s, they are typically taller than they are wide, and cloud tops can reach , or higher in the tropics. Cumulus congestus clouds are formed by the development of cumulus mediocris generally, though they can also be formed from

altocumulus castellanus In meteorology, Altocumulus castellanus or Altocumulus castellatus (ACCAS) is a cloud type named for its tower-like projections that billow upwards from the base of the cloud. The base of the cloud can form as low as 2,000 metres (6,500 feet), or ...

or stratocumulus castellanus, which are forms of cumulus castellanus. The ''congestus'' species of cloud can only be found in the genus ''cumulus'' and is designated as ''towering cumulus'' (TCu) by the

International Civil Aviation Organization The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international sc ...

(ICAO). Congestus clouds are capable of producing severe

turbulence In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

and showers of moderate to heavy intensity. This species is classified as vertical or multi-étage and is coded C_L2 in the synop report. These clouds are usually too large and opaque to have any opacity or pattern-based varieties. Congestus and especially cumulonimbus are hazardous to aviation. An approaching

weather front A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For in ...

often brings mid level clouds such as

altostratus Altostratus is a middle-altitude cloud genus made up of water droplets, ice crystals, or a mixture of the two. Altostratus clouds are formed when large masses of warm, moist air rise, causing water vapor to condense. Altostratus clouds are usuall ...

altocumulus Altocumulus (From Latin ''Altus'', "high", ''cumulus'', "heaped") is a middle-altitude cloud genus that belongs mainly to the ''stratocumuliform'' physical category characterized by globular masses or rolls in layers or patches, the individual ele ...

which when expansive and dense reduces insolation and infringes cumulus from reaching the congestus stage. Occasionally, however, particularly if the air below the mid level cloud is very warm or unstable, some of the cumuli may become congestus and the tops of them may rise above the mid level cloud layer, sometimes resulting in showers ahead of the main

rainband A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar ima ...

. This is often a sign the approaching front contains at least a few cumulonimbi amongst the

nimbostratus A nimbostratus cloud is a multi-level, amorphous, nearly uniform and often dark grey cloud that usually produces continuous rain, snow or sleet but no lightning or thunder.thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...

s. Cumulus congestus will mature into cumulonimbus calvus under conditions of sufficient

instability In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...

. This transformation can be seen by the presence of smooth, fibrous, or striated aspects assumed by the cloud's upper part. While all congestus produce showers, this development could produce heavy precipitation (meteorology), precipitation. A flammagenitus cloud, or pyrocumulus, (FgCu or FgCu con) is a rapidly growing convective cloud associated with volcanic eruptions and large-scale fires (typically wildfires. Pyrocumulus congestus may thus form under those special circumstances that can also cause severe turbulence. Cumulus congestus can also be associated with Waterspout#Non-tornadic, fair weather waterspouts forming from rotation at the open water surface being stretched and tightened under their Vertical draft, updraft. Landspouts most often form under congestus, as well. Both of these non-mesocyclone associated tornadoes typically dissipate when a more pronounced precipitation shaft forms and the downdraft cuts off this process. In highly wind shear, sheared environments or within the Flanking line (meteorology), flanking line of a supercell congestus can rotate and on rare occasions produce mesocyclonic type tornadoes, with waterspouts and landspouts emanating from misocyclones, a related but distinct process.

Turkey tower

Turkey tower is a slang term for a narrow, tall, individual towering cloud from a small cumulus cloud which develops and suddenly falls apart. Sudden development of turkey towers could signify the breaking or weakening of a capping inversion, and an area where these consistently form is an "agitated area", a term that applies to congestus generally.

References

{{DEFAULTSORT:Cumulus Castellanus Cloud Cumulus

Description

Turkey tower

See also

Bibliography

References