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47 terms

Chapter 10

STUDY
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ordinary cell thunderstorms
A thunderstorm produced by local convection within a conditionally unstable air mass
cumulus stage
the initial stage in the development of an ordinary cell thunderstorm in which rising, warm, humid air develops into a cumulus cloud
mature stage
the second stage in the three-stage cycle of an ordinary thunderstorm
dissipating stage
the final stage in the development of an ordinary cell thunderstorm when downdrafts exist through-out the cumulonimbus cloud
multicell thunderstorm
thunderstorms often in a line, each of which may be in a different stage of its life cycle
overshooting top
a situation in a mature thunderstorm when rising air, associated with strong convection, penetrates into a stable layer, forcing the upper part if the cloud to rise above its relatively flat top
gust front
a boundary that separates a cold downdraft of a thunderstorm from warm, humid surface air.
straight-line winds
strong winds created by a thunderstorms downdraft that flows outward, away from the storm in a straight line, more or less parallel to the ground
shelf cloud
a dense, arch-shaped, ominous-looking cloud that often forms along the leading edge of a thunderstorm's gust front, especially when stable air rises up and over cooler air at the surface
roll cloud
a dense, roll-shaped, elongated cloud that appears to slowly spin about a horizontal axis behind that leading edge of a thunderstorm's gust
outflow boundary
a surface boundary separating cooler more-dense air from warmer less-dense air.
downburst
A severe localized downdraft that can be experienced beneath a severe thunderstorm
microburst
a strong localized downdraft less than 4km wide that occurs beneath thunderstorms
heat burst
a sudden increase in surface air temperature often accompanied by extreme drying
squall line
a line of thunderstorms that from along a cold from or out ahead of it
bow echo
a line of thunderstorms on a radar screen that appears in the shape of a bow
derecho
strong, damaging, straight-line winds associated with a cluster of severe thunderstorms that most often form in the evening or at night
Mesoscale Convective Complexes
a large organized convective weather system comprised of a number of individual thunderstorms
supercell
a severe thunderstorm that consists primarily of a single rotating updraft
mesocyclone
a vertical column of cyclonically rotating air within a supercell thunderstorm
wall cloud
an area of rotating clouds that extends beneath a supercell thunderstorm and from which a funnel cloud may appear
flash floods
a flood that rises and falls quite rapidly with little or no advance warning, usually as the result of intenserainfall over a relatively small area
lightning
a visible electrical discharge produced by thunderstorms
thunder
the sound due to rapidly expanding gases along the channel of a lightning discharge
sonic boom
a loud explosive-like sound caused by a shock wave emanating from an aircraft traveling at or above the speed of sound
stepped leader
an initial discharge of electrons that proceeds intermittently toward the ground in a series of steps in a cloud-to-ground lightning stroke
return stroke
the luminous lightning stroke that propagates upward from the earth to the base of a cloud
dart leader
the discharge of electrons that proceeds intermittenly toward the ground along the same ionized channel taken by the initial lightning stroke
dry lightning
lightning that occurs with thunderstorms that produce little, if any, appreciable precipitation that reaches the surface
heat lightning
distant lightning that illuminates the sky but is too far away for its thunder to be heard
Saint Elmo's Fire
a bright electric discharge that is projected from objects when they are in a strong electric field, suchas during a thunderstorm
tornado
an intense, rotating column of air that often protrudes from a cumuliform cloud in the shape of a funnel or a rope whose circulation is present on the ground
funnel cloud
a tornado whose circulation has not reached the ground
tornado alley
a region in the great plains of the US extending from Texas and OK northward into Kansas and Nebraska where tornadoes are most frequent
suction vortices
small, rapidly rotating whirls perhaps 10m in diameter that are found within large tornadoes
tornado watch
a forecast issued to alert the public that tornadoes may develop within a specified area
tornado warning
a warning issued when a tornado has actually been observed either visually or on a radar screen
Fujita scale
a scale developed by T Theodore Fujita for classifying tornadoes according to the damage they cause and their rotational wind speed
Enhanced Fujita Scale
a modification of the original fujita scale that describes tornado intensity by observing damage caused by the tornado
tornado outbreak
a series of tornadoes that forms within a particular region- a region that may include several states
supercell tornadoes
tornadoes that occur within supercell thunderstorms that contain well-developed, mid-level mesocyclones
hook echo
the shape of an echo on a doppler radar screen that indicates the possible presence of a tornado
nonsupercell tornadoes
a tornado that occurs with a cloud tha tis often in its growing stage, and one that does not contain a mid-level mesocyclone, or wall cloud
gustnadoes
a relatively weak tornado associated with a thunderstorms outflow
landspout
relatively weak nonsupercell tornado that originateswith a cumiliform cloud in its growth stage and with a cloud that does not contain a mid-level mesocyclone
NEXRAD
an acronym for next generation weather radar
waterspout
a column of rotating wind over water that has characteristics of a dust devil and tornados