Cumulonimbus clouds are high and dense, which are formed by instability in the atmosphere. These clouds are known to produce powerful weather effects such as storms. The clouds are classified as rising cloud types. The clouds form at around 3000 metres using convective updrafts, they rise to greater heights of about 12000 metres. However, during severe updrafts, the clouds are known to be able to rise past 23000 metres.
Cumulonimbus clouds are mostly made up of water droplets, however towards higher altitudes, where the temperature dips below zero degrees centigrade, the clouds are made up entirely of ice crystals. When the clouds reach a height of approximately 16000 metres, high winds and inversion together with increased temperatures, makes the top of the clouds flat.
The surface warming makes warm air parcels together with moisture rise up in the atmosphere and undergo a convection process. At higher layers, specifically at the transition zone, the cold air mixes into the parcel and the parcel cools. As long as the air in he parcel is warmer than its exterior environment, it will continue to rise. As the parcel of air cools it condenses into clouds. However. Cumulonimbus clouds undergo formation when a front of cool air meets and interacts with a parcel of hot, moist air, on its way up. As the Cumulus congestus clouds grow vertically from lower levels, they eventually become Cumulonimbus clouds, that form in clusters, either on their own or in a cold front line.
Cumulonimbus can be considered to be one of the most violent and weather effecting clouds types. They are known to produce rain, hail, snow, thunderstorms and tornadoes. The clouds are also known to create powerful straight line winds.With enough latent heat and convection, Cumulonimbus clouds grow into larger storms or super cells; which can create tornadoes, larger storms, mesocyclones and high winds. Cumulonimbus clouds have poweful convective currents with unpredictable winds.
There are numerous amounts of Cumulonimbus clouds. These can be identified by shape, size and general species allocation. These are:
Cb Capillatus, are fully developed cumulonimbus clouds with a fibrous top. These extend from the ground and up to the tropopause.
Cb Arcus, a low and horizontal cloud which is on the leading edge of thunderstorms.
Cb Calvus, are tall and precipitate, but without the height needed to display a an anvil.
Cb Incus, is of Cumulonimbus capillatus cloud, but with flat anvil top.
Cb Tuba, is a different type of the capillatus cloud. It is long and straight, and points down.
Cb Virga, a cumulonimbus cloud that has an observable streak of precipitation. The rain, however, evaporates before reaching the ground.
Cb Mammatus, is a pattern of cellular pouches.
Cb Praecipitatio, a rainy type of cumulonimbus cloud.
Cb Pannus, are cloud shreds below the main cloud or a separating layer in the cloud.
Cb Pileus, a small, horizontal cloud that lies above a cumulus formation. This in turn creates a hood formation.
Cb Velum, A cumulus cloud where the pileus cap becomes part of the cumulus.
Cumulonimbus clouds begin to dissipate when the downdraft of hot air overpowers the updraft of cool air. The clouds exhaust themselves and die quickly after dumping rain and other weather phenomena. However, when conditions are warm and moist, more clouds are formed in a chain reaction, one after the other. These conditions can create thunderstorms.