CUMULONIMBUS
Cumulonimbus, from the Latin cumulus ("heap") and nimbus ("rainstorm", "storm cloud"), is a dense towering vertical cloud associated with thunderstorms and atmospheric, forming from water vapor carried by powerful upward air currents.
ü Cumulonimbus can form alone, in clusters, or along cold front squall lines. These clouds are capable of producing lightning and other dangerous severe weather, such as gusts, hail, and occasional tornadoes. Cumulonimbus progress from overdeveloped cumulus congests clouds and may further develop as part of a super cell.
ü Cumulonimbus clouds are typically accompanied by lower altitude cumulus clouds, growing vertically instead of horizontally, contributing to the mushroom shape of the cumulonimbus. The cumulonimbus base may extend several miles across and occupy low to middle altitudes- formed at altitude from approximately 500 to 13,000 ft (200 to 4,000 m).
ü Well-developed cumulonimbus clouds are characterized by a flat, anvil-like top (anvil dome), caused by wind shear or inversion near the tropopause. The shelf of the anvil may precede the main cloud's vertical component for many miles, and be accompanied by lightning. Occasionally, rising air parcels surpass the equilibrium level (due to momentum) and form an overshooting top culminating at the maximum parcel level. When vertically developed, this largest of all clouds usually extends through all three cloud regions. Even the smallest cumulonimbus cloud dwarfs its neighbors in comparison.
Species
- Cumulonimbus calvus: cloud with puffy top, similar to cumulus congests which it develops from; under the correct conditions in can become a cumulonimbus capillatus
- Cumulonimbus capillatus - cloud with cirrus-like, fibrous-edged top.
Effects
Cumulonimbus storm cells can produce torrential rain 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.
Cumulonimbus clouds can also bring dangerous winter storms (called "blizzards") which bring lightning, thunder, and torrential snow. However, cumulonimbus clouds are most common in tropical regions.
