A
funnel cloud is a
funnelA funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel,spillage would occur....
-shaped
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...
of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud (usually a
cumulonimbusCumulonimbus 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. They create lightning through the heart of the cloud...
or towering
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...
) 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 baseThis article refers to meteorology, for the airborne base of Captain Scarlet see Cloudbase.The cloud base is the lowest altitude of the visible portion of the cloud...
. Funnel clouds form most frequently in association with
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...
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.
If a funnel cloud touches the ground it becomes a
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...
.
A
funnel cloud is a
funnelA funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel,spillage would occur....
-shaped
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...
of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud (usually a
cumulonimbusCumulonimbus 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. They create lightning through the heart of the cloud...
or towering
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...
) 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 baseThis article refers to meteorology, for the airborne base of Captain Scarlet see Cloudbase.The cloud base is the lowest altitude of the visible portion of the cloud...
. Funnel clouds form most frequently in association with
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...
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.
If a funnel cloud touches the ground it becomes a
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...
. Most tornadoes begin as funnel clouds, but many funnel clouds do not make ground contact and so do not become tornadoes. Also, a tornado does not necessarily need to have an associated
condensationCondensation is the change of the physical state of aggregation of matter from gaseous phase into liquid phase and the reverse of evaporation. When the transition happens from the gaseous phase into the solid phase directly, bypassing the liquid phase, the change is called deposition...
funnel—if strong
cyclonicIn meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. This is usually characterized by inward spiraling winds that rotate counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth.Large-scale...
winds are occurring at the surface (and connected to a cloud base, regardless of condensation), then the feature is a tornado. Some tornadoes may appear only as a debris swirl, with no obvious funnel cloud extending below the rotating cloud base.
A funnel cloud that touches down on, or moves over water is a
waterspoutA waterspout is an intense columnar vortex that occurs over a body of water and is connected to a cumuliform cloud. In the common form, it is a non-supercell tornado over water. While it is often weaker than most of its land counterparts, stronger versions spawned by mesocyclones do occur...
.
Cold-air funnel clouds
Cold-air funnel clouds (vortices) are usually short-lived and generally much weaker than the vortices produced by supercells. Although cold-air funnels rarely make ground contact, they may touch down briefly and become weak tornadoes or waterspouts.
Unlike the related phenomenon associated with severe thunderstorms, cold-air funnels are generally associated with partly cloudy skies in the wake of
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:...
s, where atmospheric instability and moisture is sufficient to support towering
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 but not precipitation. The mixing of cooler air in the lower
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....
with air flowing in a different direction in the middle troposphere causes the rotation on a horizontal axis, which, when deflected vertically by atmospheric conditions, can become a funnel cloud.
They are a common sight along the Pacific Coast of the USA, particularly in the spring or autumn.
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