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Meteorology  Walker circulation  Warm Advection

Wall Clouds Beneath CB Towers visual clues of storm potential
Here we have a southward view of a supercell, with precipitation in the right middle-ground and a wall cloud beneath the cumulonimbus (Cb) tower and anvil overhang in the background.


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A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm.

Wall Cloud - A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm.

Wall cloud An area of rotating clouds that extends beneath a severe thunderstorm and from which a funnel cloud may appear.
Warm-core low A low-pressure area that is warmer at its center than at its periphery. Tropical cyclones exhibit this temperature pattern.

WALL CLOUD -An isolated lowering of a cloud that is attached to the rain-free base of a thunderstorm, generally to the rear of the visible precipitation area. Wall clouds indicate the updraft of or the inflow to a thunderstorm.

~ Local lowering of a cumulonimbus cloud associated with a humid updraft; may develop into a mesocyclone and tornado.
Warm air advection The flow of air from a relatively warm locality to a relatively cool locality.

~—The well-defined bank of vertically developed clouds having a wall-like appearance which form the outer boundary of the eye of a well-developed tropical cyclone.
warm front—Any non-occluded front which moves in such a way that warmer air replaces colder air.

~
An abrupt lowering of a cloud from its parent cloud base, a cumulonimbus or supercell, with no visible precipitation underneath. Forming in the area of a thunderstorm updraft, or inflow area, it exhibits rapid upward movement and cyclonic rotation.

~- A local and often abrupt lowering of a rain-free cumulonimbus base into a low-hanging accessory cloud, from 1 to 4 miles in diameter.

~ - An area of clouds that extends beneath a severe thunderstorm. If a wall cloud rotates, it might precede tornado development.

~
The wall cloud forms near the downdraft/updraft interface. This "interface" is the area between the precipitation area and the precipitation-free base. ~s form when rain-cooled air from the downdraft is pulled into the updraft.

~ - It's an area of clouds that extends underneath a thunderstorm. If a wall cloud rotates, it might form a tornado.
Warm Front - The boundary between two air masses, one cool and the other warm, moving so that the warmer air replaces the cooler air.

~ - A lowered cloud base on the backside (upwind) side of a thunderstorm associated with thunderstorm inflow. A rotating wall cloud can signify the presence of a mesocyclone.

"~" also is used occasionally in tropical meteorology to describe the inner cloud wall surrounding the eye of a tropical cyclone, but the proper term for this feature is eyewall.Warm AdvectionTransport of warm air into an area by horizontal winds.

Eyewall / Wall Cloud: An organized band or ring of cumulonimbus clouds that surround the eye, or light-wind center of a tropical cyclone. Eyewall and wall cloud are used synonymously.

Eye Wall/Wall Cloud
An organized band of cumuliform clouds immediately surrounding the center of a tropical cyclone. Eye wall and wall cloud are used synonymously.

arcus (arc) - arch, shelf, roll or wall cloud
incus (inc) - anvil
mamma (mam) - pouches hanging from underneath main clouds
pannus (pan) - ragged shreds of cloud
pileus (pil) - cap cloud ...

Clear slotA local region of clearing skies or reduced cloud cover, indicating an intrusion of drier air; often seen as a bright area with higher cloud bases on the west or southwest side of a wall cloud.ClimateThe prevalent long term weather conditions in a particular area.

Tornadoes may develop from wall clouds attached to the rain-free base, or from the rain-free base itself - especially when the rain-free base is on the south or southwest side of the main precipitation area.

Clear SlotWith respect to severe thunderstorms, a local region of clearing skies or reduced cloud cover, indicating an intrusion of drier air; often seen as a bright area with higher cloud bases on the west or southwest side of a wall cloud.

TAFTerminal Aerodrome ForecastTAFBTropical Analysis and Forecast Branch (of the TPC)Tail CloudA horizontal, tail-shaped cloud (not a funnel cloud) at low levels extending from the precipitation cascade region of a supercell toward the wall cloud (i.e.

Tail Cloud A horizontal, tail-shaped cloud (not a funnel cloud) at low levels extending from the precipitation cascade region of a supercell toward the wall cloud (i.e., it usually is observed extending from the wall cloud toward the north or northeast).

A "true" tail cloud typically is attached to the wall cloud and has a cloud base at about the same level as the wall cloud itself.

A "true" tail cloud is attached to the wall cloud and has a cloud base at about the same level as the wall cloud itself.

Eye: The relatively calm center in a hurricane that is more than one half surrounded by wall cloud. The winds are light, the skies are partly cloudy or even clear (the skies are usually free of rain) and radar depicts it as an echo-free area within the eye wall.

It often is visible as a clear slot wrapping around the wall cloud. Scattered large precipitation particles (rain and hail) at the interface between the clear slot and wall cloud may show up on radar as a hook or pendant; thus the presence of a hook or pendant may indicate the presence of an RFD.

Tail Cloud - A low tail-shaped cloud extending outward from the northern quadrant of a wall cloud. Motions in the tail cloud are toward the wall cloud with rapid updraft at the junction of tail and wall cloud. This horizontal cloud is not a funnel or tornado.

A generally circular ring of cloud that may be observed on rare occasions surrounding the upper part of a wall cloud. This term sometimes is used (incorrectly) as a synonym for wall cloud.
Collection Efficiency
The fraction of droplets approaching a surface that actually deposit on that surface.

Radar and satellite imagery often show that the eye wall clouds are the inner-most coil of a series of spiral rain-band clouds that extend hundreds of kilometres from the centre and typically produce very strong wind squalls.

[Slang], a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar).

The air rises, cools and condenses, releasing latent heat and forming the towering eye wall cloud, still spiraling as it climbs. At the top of the storm, a dome of high pressure over the eye presses the air outwards, forming the outgoing spirals of cirrus cloud seen in satellite photographs.

A small, weak tornado, which is not formed by a storm-scale rotation. It is generally weaker than a supercell tornado and is not associated with a ~ or mesocyclone. It may be observed beneath cumulonimbus or towering cumulus clouds and is the land equivalent of a waterspout.

The third type is the squall line composed of a line of convective clouds which share a common gust front along the leading edge (sometimes seen as a ~). They can move at rapid speeds and produce heavy rainfall and moderate hail, sometimes resulting in flash flooding.

See also: See also: What is the meaning of Cloud, Storm, Clouds, Air, Precipitation?

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