This MedLibrary.org supplementary page on Cumulonimbus is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
 |
This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (November 2008) |
| Cumulonimbus cloud | |
 Cumulonimbus cloud (calvus-type) |
|
| Abbreviation | Cb |
|---|---|
| Symbol |  |
| Genus | Cumulonimbus (heap, cloud/severe rain) |
| Altitude | 2,000–16,000 m (6,500–60,000 ft) |
| Classification | Family D (Vertically developed) |
| Appearance | Very tall and large clouds |
| Precipitation cloud? | Yes, often intense, but may be virga |
Cumulonimbus (Cb) is a type of cloud that is tall, dense, and involved in thunderstorms and other intense weather. It is a result of atmospheric instability. These clouds can form alone, in clusters, or along a cold front in a squall line. Cumulonimbus clouds form from cumulus clouds (namely from cumulus congestus) and can further develop into a supercell, a severe thunderstorm with special features.
Contents |
Appearance
Cumulonimbus clouds usually form from cumulus clouds at a much lower height, thus making them, like cumulus clouds, grow vertically instead of horizontally, thus giving the cumulonimbus its mushroom shape. The base of a cumulonimbus can be several miles across, and it can be tall enough to occupy middle as well as low altitudes; though formed at an altitude of about 3,000 to 4,000 meters (10,000 to 12,000 feet), its peak can reach up to 23,000 meters (75,000 feet)citation needed in extreme cases. Typically, it peaks at a much lower height (usually up to 5,000 meters / 16,500 feet).verification needed. Well-developed cumulonimbus clouds are also characterized by a flat, anvil-like top (anvil dome), caused by straight line winds at the higher altitudes which shear off the top of the cloud, as well as by an inversion over the thunderstorm caused by rising temperatures above the tropopause. This anvil shape can precede the main cloud structure for many miles, causing anvil lightning. This is the tallest of the clouds.
Cumulonimbus clouds can be subdivided into several species:
- Cumulonimbus arcus
- Cumulonimbus calvus- cloud with puffy top, looking like cumulus congestus, but larger;
- Cumulonimbus capillatus - cloud with cirrus-like, fibrous-edged top;
- Cumulonimbus incus - subtype of Cumulonimbus capillatus, with flat anvil-like top.
- Cumulonimbus mammatus
- Cumulonimbus pannus
- Cumulonimbus pileus
- Cumulonimbus praecipitatio
- Cumulonimbus tuba
- Cumulonimbus velum
- Cumulonimbus virga
Effects
Cumulonimbus storm cells can produce heavy rain (particularly of a convective nature) and flash flooding, as well as straight-line winds. Most storm cells die after about 20 minutes, when the precipitation causes more downdraft than updraft, causing the energy to dissipate. If there is enough solar energy in the atmosphere, however (on a hot summer's day, for example), the moisture from one storm cell can evaporate rapidly — resulting in a new cell forming just a few miles from the former one. This can cause thunderstorms to last for several hours. This multicell cloud structure exists until cold downdraft preceding cumulonimbus at ground level flows before cloud at distance sufficient to disrupt updraft (5-10 kilometers). From this moment on, cumulonimbus cloud quickly degrades and dissipates, forming cirrus spissatus, dense anvil-like cirrus, stratocumulus diurnalis or stratocumulus vesperalis.
Cumulonimbus clouds sometimes form mammatus clouds.
Cumulonimbus clouds contain severe convection currents, with very high, unpredictable winds, particularly in the vertical plane (updrafts and downdrafts). They are therefore extremely dangerous to aircraft. Smaller, propeller-driven planes cannot cope with the conditions and must fly around them; larger jet aircraft fly over the smaller ones and around larger examples. Larger planes are also equipped with weather radar and wind shear detectors to help guide them through, in the event that they need to pass through such clouds to land. They also can snow because they are also in the higher part of the atmosphere.
The air convection can also form mesocyclones, which can cause hail and tornadoes.
See also
- Cumulonimbus calvus
- Cumulonimbus incus
- Cumulus congestus cloud
- Funnel cloud
- Hot tower
- Mammatus cloud
- Pileus
- Pyrocumulonimbus
- Squall line
- Storm
- Supercell
- Tornado
External links
 |
Wikimedia Commons has media related to: Cumulonimbus clouds |
- Clouds-Online.com Cloud Atlas with many photos and description of the different cloud genus
- Cumulonimbus cloud at BBC Weather
- Weather Pictures and Storm Chasing – Cumulonimbus clouds
|
|||||||||||||||||
Wikipedia content modification information:
- This page was last modified on 2 December 2008, at 01:11.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Cumulonimbus".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.