AskDefine | Define thundercloud

Dictionary Definition

thundercloud n : a dark cloud of great vertical extent charged with electricity; associated with thunderstorms [syn: cumulonimbus, cumulonimbus cloud]

User Contributed Dictionary



  1. a large, dark cloud, usually a cumulonimbus, charged with electricity and producing thunder and lightning; a stormcloud
  2. In the context of "by extension": something menacing and brooding
    As the ominous thunderclouds of war gather over the Middle East, countries like France and Russia have threatened to use their veto in the United Nations to thwart immediate U.S. military force against Iraq. -


'''something menacing and brooding

Extensive Definition

Cumulonimbus (Cb) is a type of cloud that is tall, dense, and involved in thunderstorms and other intense weather. The clouds can form alone, in clusters, or along a cold front in a squall line. Cumulonimbus clouds form from cumulus clouds (namely from cumulus congestus) and can further develop to a supercell, 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. The base of a cumulonimbus can be several miles across, and it can be tall enough to occupy middle as well as low altitudes; though formed at an altitude of about 3,000 to 4,000 meters (10,000 to 12,000 feet), its peak can reach up to 23,000 meters (75,000 feet) in extreme cases. Typically, it peaks at a much lower height (usually up to 5,000 meters / 16,500 feet).
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 inversion over the thunderstorm caused by rising temperatures above the tropopause. This anvil shape can precede the main cloud structure for many miles, causing anvil lightning.
Cumulonimbus clouds = heavy rain and thunderstorms.
Cumulonimbus clouds can be subdivided into several species:


Cumulonimbus storm cells can produce heavy rain (particularly of a convective nature) and flash flooding, as well as straight-line winds. Most storm cells die after about 20 minutes, when the precipitation causes more downdraft than updraft, causing the energy to dissipate. If there is enough solar energy in the atmosphere, however (on a hot summer's day, for example), the moisture from one storm cell can evaporate 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 cold downdraft preceding cumulonimbus at ground level flows before cloud at distance sufficient to disrupt updraft (5-10 kilometers). From this moment on, cumulonimbus cloud quickly degrades and dissipates, forming cirrus spissatus, dense anvil-like cirrus, stratocumulus diurnalis or stratocumulus vesperalis.
Cumulonimbus clouds sometimes form mammatus clouds.
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 aircraft. 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 radar and wind shear 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 atmosphere.
The air convection can also form mesocyclones, which can cause hail and tornadoes.
thundercloud in Catalan: Cumulonimbus
thundercloud in Czech: Cumulonimbus
thundercloud in German: Cumulonimbus
thundercloud in Modern Greek (1453-): Σωρειτομελανίες
thundercloud in Spanish: Cumulonimbus
thundercloud in French: Cumulonimbus
thundercloud in Galician: Cumulonimbus
thundercloud in Korean: 적란운
thundercloud in Italian: Cumulonembo
thundercloud in Hebrew: קומולונימבוס
thundercloud in Hungarian: Cumulonimbus
thundercloud in Dutch: Cumulonimbus
thundercloud in Japanese: 積乱雲
thundercloud in Norwegian: Cumulonimbus
thundercloud in Norwegian Nynorsk: Cumulonimbus
thundercloud in Polish: Cumulonimbus
thundercloud in Portuguese: Cumulonimbus
thundercloud in Romanian: Cumulo-nimbus
thundercloud in Sicilian: Cumulunemmu
thundercloud in Simple English: Cumulonimbus cloud
thundercloud in Slovak: Kumulonimbus
thundercloud in Slovenian: Kumulonimbus
thundercloud in Finnish: Kuuropilvi
thundercloud in Swedish: Cumulonimbus
thundercloud in Vietnamese: Mây vũ tích
thundercloud in Ukrainian: Купчасто-дощові хмари

Synonyms, Antonyms and Related Words

Cloudcuckooland, alto-cumulus, alto-stratus, angry clouds, anvil cloud, banner cloud, billowy cloud, black cat, black clouds, broken mirror, cap cloud, cirro-cumulus, cirro-fillum, cirro-nebula, cirro-stratus, cirro-velum, cirrus, cirrus cloud, cirrus haze, cirrus stripe, cloud, cloud band, cloud bank, cloud drift, cloud mass, cloud street, cloudland, cloudling, cloudscape, cocktail, cottony cloud, cumulo-cirro-stratus, cumulo-cirrus, cumulo-nimbus, cumulo-stratus, cumulus, cumulus cloud, curl cloud, danger sign, early symptom, falling barometer, fleecy cloud, fractocumulus, gathering clouds, halcyon bird, high fog, high sign, mackerel sky, mammatocumulus, mushroom cloud, nimbus, nimbus cloud, omen, owl, precursor, preliminary sign, premonitory sign, premonitory symptom, prodroma, prodrome, quarantine flag, rain cloud, rainbow, raven, red flag, red light, scud, shooting star, skull and crossbones, snail cloud, squall cloud, storm cloud, storm clouds, storm petrel, stormy petrel, strato-cumulus, stratus, stratus cloud, symptom, thunderhead, warning sign, warning signal, water carrier, woolpack, yellow flag, yellow jack
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