Cumulonimbus (
Cb) is a type of
cloudA cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae...
that is tall, dense, and involved in
thunderstormA thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
s and other intense
weatherWeather is a set of all the phenomena occurring in a given atmosphere at a given time. Weather phenomena lie in the troposphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods...
. It is a result of atmospheric instability. These clouds can form alone, in clusters, or along a
cold frontA cold front is defined as the leading edge of a cooler and drier mass of air, replacing a warmer mass of air.-Development of cold front:...
in a
squallA squall is a sudden, sharp increase in wind speed which is usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to an increase in the sustained winds over a short time interval, as there may be higher gusts during a squall event...
line. They create
lightningLightning is an atmospheric discharge of electricity accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
through the heart of the cloud. Cumulonimbus clouds form from
cumulus cloudCumulus clouds are a type of cloud with noticeable vertical development and clearly defined edges. Cumulus means "heap" or "pile" in Latin. They are often described as "puffy" or "cotton-like" in appearance. Cumulus clouds may appear alone, in lines, or in clusters...
s (namely from
cumulus congestusCumulus congestus clouds are characteristic of unstable areas of the atmosphere which are undergoing convection. They are often characterized by sharp outlines and great vertical development. Because cumulus congestus is produced by strong updrafts, it is typically taller than it is wide, and...
) and can further develop into a
supercellA supercell is a thunderstorm that is characterized by the presence of a mesocyclone; a deep, continuously-rotating updraft. Of the four classifications of thunderstorms , supercells are the overall least common and have the potential to be the most severe...
, a severe thunderstorm with special features.
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.
Cumulonimbus (
Cb) is a type of
cloudA cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae...
that is tall, dense, and involved in
thunderstormA thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
s and other intense
weatherWeather is a set of all the phenomena occurring in a given atmosphere at a given time. Weather phenomena lie in the troposphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods...
. It is a result of atmospheric instability. These clouds can form alone, in clusters, or along a
cold frontA cold front is defined as the leading edge of a cooler and drier mass of air, replacing a warmer mass of air.-Development of cold front:...
in a
squallA squall is a sudden, sharp increase in wind speed which is usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to an increase in the sustained winds over a short time interval, as there may be higher gusts during a squall event...
line. They create
lightningLightning is an atmospheric discharge of electricity accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
through the heart of the cloud. Cumulonimbus clouds form from
cumulus cloudCumulus clouds are a type of cloud with noticeable vertical development and clearly defined edges. Cumulus means "heap" or "pile" in Latin. They are often described as "puffy" or "cotton-like" in appearance. Cumulus clouds may appear alone, in lines, or in clusters...
s (namely from
cumulus congestusCumulus congestus clouds are characteristic of unstable areas of the atmosphere which are undergoing convection. They are often characterized by sharp outlines and great vertical development. Because cumulus congestus is produced by strong updrafts, it is typically taller than it is wide, and...
) and can further develop into a
supercellA supercell is a thunderstorm that is characterized by the presence of a mesocyclone; a deep, continuously-rotating updraft. Of the four classifications of thunderstorms , supercells are the overall least common and have the potential to be the most severe...
, a severe thunderstorm with special features.
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
altitudeAltitude is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object...
s; though formed at an altitude of about 500 to 13,000 feet (150 to 3,960 meters), its peak can reach up to 75,000 feet (23,000 meters) in extreme cases. Typically, it peaks at a much lower height, usually up to 20,000 feet (6,090 meters)..
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
inversionIn meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to a temperature inversion, i.e., an increase in temperature with height, or to the layer within which such an increase occurs...
over the thunderstorm caused by rising temperatures above the
tropopauseThe tropopause is the atmospheric boundary between the troposphere and the stratosphere. Going upward from the surface, it is the point where air ceases to cool with height, and becomes almost completely dry. More formally, it is the region of the atmosphere where the lapse rate changes from...
. This anvil shape can precede the main cloud structure for many miles, causing anvil
lightningLightning is an atmospheric discharge of electricity accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
. This is the tallest of the clouds.
Species
- Cumulonimbus arcus
An arcus cloud is a low, horizontal cloud formation associated with the leading edge of thunderstorm outflow, or occasionally with a cold front even in the absence of thunderstorms...
- Cumulonimbus calvus
Cumulonimbus calvus is a moderately tall cumulonimbus cloud which is capable of precipitation, but has not yet reached the height where it forms into a cumulonimbus capillatus or cumulonimbus incus...
– cloud with puffy top, similar to cumulus congestus, but larger;
- Cumulonimbus capillatus – cloud with cirrus-like, fibrous-edged top;
- Cumulonimbus incus
A cumulonimbus incus is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It can cause a supercell and then a tornado....
– subtype of Cumulonimbus capillatus, with flat anvil-like top.
- Cumulonimbus mammatus
- Cumulonimbus pannus
Fractus clouds are small, ragged cloud fragments which, usually found under an ambient cloud base, form or have broken off a larger cloud, and are generally sheared by and shredded-looking due to strong winds. Fractus have irregular patterns, appearing much like torn pieces of cotton candy, change...
- Cumulonimbus pileus
- Cumulonimbus praecipitatio
- Cumulonimbus tuba
A funnel cloud is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud but not reaching the ground or a water surface. A funnel cloud is usually visible as a cone-shaped or needle like protuberance from the main cloud...
- Cumulonimbus velum
- Cumulonimbus virga
Effects
Cumulonimbus storm cells can produce heavy
rainRain is liquid precipitation, as opposed to other kinds of precipitation such as snow, hail and sleet. On Earth, it is the condensation of atmospheric water vapor into drops heavy enough to fall, often making it to the surface...
(particularly of a
convectiveConvection is the movement of molecules within fluids . Convection is one of the major modes of heat transfer and mass transfer...
nature) and
flash floodA flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers and streams. It is caused by heavy rain associated with a thunderstorm, hurricane, or tropical storm. Flash floods can also occur after the collapse of an ice dam, or a human structure, such as a dam, for example, the...
ing, as well as straight-line winds. Most storm cells die after about 20 minutes, when the
precipitationIn meteorology, precipitation is any product of the condensation of atmospheric water vapor that is deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel...
causes more downdraft than updraft, causing the energy to dissipate. If there is enough solar energy in the
atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
, however (on a hot summer's day, for example), the moisture from one storm cell can
evaporateEvaporation is the vaporization of a liquid and the reverse, of condensation. A type of phase transition, it is the process by which molecules in a liquid state spontaneously become gaseous . Generally, evaporation can be seen by the gradual disappearance of a liquid from a substance when exposed...
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 a cold downdraft preceding the cumulonimbus at ground level flows before the cloud at a distance sufficient to disrupt updraft (5–10 kilometers). From this moment on the cumulonimbus cloud quickly degrades and dissipates, forming cirrus spissatus, dense anvil-like
cirrusCirrus clouds generally refer to atmospheric clouds that are characterized by thin, wisplike strands, often accompanied by tufts, leading to their common name of mare's tail. Sometimes these clouds are so extensive that they are virtually indistinguishable from one another, forming a sheet of...
, stratocumulus diurnalis or stratocumulus vesperalis.
Cumulonimbus clouds sometimes form
mammatus cloudMammatus, also known as mammatocumulus, meaning "Mammary cloud" or "Breast cloud" is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud...
s.
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
aircraftAn aircraft is a vehicle which is able to fly by being supported by the air, or in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil An aircraft is a vehicle which is able to fly by being supported...
. 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
radarRadar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for RAdio Detection And...
and
wind shearWind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
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 snowy atmosphere
The air convection can also form
mesocycloneA mesocyclone is a vortex of air, approximately 2 to 10 km in diameter , within a convective storm....
s, which can cause
hailHail is a form of solid precipitation which consists of balls or irregular lumps of ice, that are individually called hail stones. Hail stones on Earth consist mostly of water ice and measure between 5 and 150 millimeters in diameter, with the larger stones coming from severe and dangerous...
and
tornadoA tornado is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud...
es.
Cloud Types
CloudA cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae...
s form when the dewpoint of
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
is reached in the presence of condensation nuclei in the
troposphereThe troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75 percent of the atmosphere's mass and 99 percent of its water vapor and aerosols....
. Atmosphere is a dynamic system, and the local conditions of
turbulenceIn fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. Flow that is not turbulent is called laminar flow...
,
upliftUplift may refer to:* Biological uplift, the theoretical prospect of upgrading the capacities of a species or a civilization.** Uplift Universe, the setting for a series of novels by David Brin in which Biological Uplift is a central aspect...
and other parameters give rise to many types of clouds. Various types of clouds occur frequently enough to have acquired a name of their own, often these are further specified with additional descriptive name. Furthermore, some atmospheric processes can make the clouds organize in distinct patterns such as '
wave cloud-Formation:A wave cloud is a cloud form created by atmospheric standing waves. These waves are created as stable air flows over a mountain range, and can either form above or in the lee of the range. As an air mass travels through the wave, it undergoes repeated uplift and descent. If there is...
' or '
actinoform cloudAn actinoform or actiniform cloud is a collection of marine low clouds that takes a distinct shape. They are named after the Greek word for "ray" due to their radial structure. Actinoform clouds can spread out over 300 kilometers across and thus cannot be easily seen with the naked eye...
', these are large scale structures and not always readily identifiable from single point of view.
There are also Scirocco and Chinook clouds along with a lot of other types of clouds.
See also
- Cumulonimbus calvus
Cumulonimbus calvus is a moderately tall cumulonimbus cloud which is capable of precipitation, but has not yet reached the height where it forms into a cumulonimbus capillatus or cumulonimbus incus...
- Cumulonimbus incus
A cumulonimbus incus is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It can cause a supercell and then a tornado....
- Cumulus congestus cloud
Cumulus congestus clouds are characteristic of unstable areas of the atmosphere which are undergoing convection. They are often characterized by sharp outlines and great vertical development. Because cumulus congestus is produced by strong updrafts, it is typically taller than it is wide, and...
- Funnel cloud
A funnel cloud is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud but not reaching the ground or a water surface. A funnel cloud is usually visible as a cone-shaped or needle like protuberance from the main cloud...
- Mammatus cloud
Mammatus, also known as mammatocumulus, meaning "Mammary cloud" or "Breast cloud" is a meteorological term applied to a cellular pattern of pouches hanging underneath the base of a cloud...
- Pileus
A pileus is a small, horizontal cloud that can appear above a cumulus or cumulonimbus cloud, giving the parent cloud a characteristic "hoodlike" appearance. Pilei tend to change shape rapidly. They are formed by strong updrafts acting upon moist air at lower altitudes, causing the air to cool to...
- Pyrocumulonimbus
The pyrocumulonimbus cloud is a type of cumulus cloud formed above a source of heat such as a wildfire and may sometimes even extinguish the fire that formed it. It is the most extreme manifestation of pyrocumulus...
- Squall line
A squall is a sudden, sharp increase in wind speed which is usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to an increase in the sustained winds over a short time interval, as there may be higher gusts during a squall event...
- Storm
A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
- Supercell
A supercell is a thunderstorm that is characterized by the presence of a mesocyclone; a deep, continuously-rotating updraft. Of the four classifications of thunderstorms , supercells are the overall least common and have the potential to be the most severe...
- Tornado
A tornado is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud...
External links