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thunder: Definition, Synonyms and Much More from Answers.com

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The acoustic radiation produced by thermal lightning channel processes. The lightning return stroke is a high surge of electric current that has a very short duration, depositing approximately 95% of its electrical energy during the first 20 microseconds. Spectroscopic studies have shown that the lightning channel is heated to temperatures in the 20,000–30,000 K (36,000–54,000°F) range by this process. The pressure of the hot channel exceeds 10 atm (>106 pascals). The hot, high-pressure channel expands supersonically and forms a shock wave as it pushes against the surrounding air. Because of the momentum gained in expanding, the shock wave overshoots, causing the pressure in the core of the channel to go below atmospheric pressure temporarily. The outward-propagating wave separates from the core of the channel, forming an N-shaped wave that eventually decays into an acoustic wavelet. See also Shock wave; Storm electricity.

The sound that is eventually heard or detected, thunder, is the sum of many individual acoustic pulses, each a remnant of a shock wave, that have propagated to the point of observation from the generating channel segments. The first sounds arrive from the nearest part of the lightning channel and the last sounds from the most distant parts.

The higher the source of the sound, the farther it can be heard. Frequently, the thunder that is heard originates in the cloud and not in the visible channel. On some occasions, the observer may hear no thunder at all; this is more frequent at night when lightning can be seen over long distances and thunder can be heard only over a limited range (∼10 km or 6 mi). See also Lightning; Thunderstorm.


Thunder is the sound made by lightning. Depending on the nature of the lightning and distance of the hearer, it can range from a sharp, loud crack to a long, low rumble. It is produced by a sonic shock wave caused by the rapid expansion of the air surrounding and within a bolt of lightning.

The cause of thunder

The cause of thunder has been the subject of centuries of speculation and scientific inquiry. The first recorded theory is attributed to the Greek philosopher Aristotle in the third century BC, and an early speculation was that it was caused by the collision of clouds. Subsequently, numerous other theories have been proposed. By the mid-19th century, the accepted theory was that lightning produced a vacuum along its path, and that thunder was caused by the subsequent motion of air rushing to fill the vacuum. Later in the 19th century it was believed that thunder was caused by an explosion of steam when water along the lightning channel was heated. Another theory was that gaseous materials were created by lightning and then exploded. In the 20th century a consensus evolved that thunder must begin with a shock wave in the air due to the sudden thermal expansion of the plasma in the lightning channel. In a fraction of a second the air is heated to a temperature approaching 28,000 °C (50,000 °F)[1]. This heating causes it to expand outward, plowing into the surrounding cooler air at a speed faster than sound would travel in that cooler air. The outward-moving pulse that results is a shock wave, similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft.

More recently, this consensus has been eroded by the observation that measured overpressures in simulated lightning are greater than what could be achieved by the amount of heating found. Alternative proposals rely on electrodynamic effects of the massive current acting on the plasma in the bolt of lightning. [2]

Etymology

The d in thunder is epenthetic, and is now found in Modern Dutch donder, from earlier Old English þunor, Middle Dutch donre, together with Old Norse þorr, Old Frisian þuner, Old High German donar descended from Proto-Germanic *þunraz. In Latin it's tonare "to thunder" (see also tornado). The name of the Germanic god Thor comes from the Old Norse word for thunder.

See also:

Calculating distance

A flash of lightning, followed after some seconds by a rumble of thunder, is for many people the first illustration of the the fact that sound (like light) does not travel instantaneously, and that sound is by far the slower. Using this difference, one can estimate how far away the bolt of lightning is by timing the interval between seeing the flash and hearing thunder. The speed of sound in air is approximately 340 m/s or 762 mph. The speed of light can be assumed to be infinite in this calculation because one must know that there has been a lightning strike before starting counting. Therefore, the lightning is approximately one kilometer distant for every three seconds (or one mile for every five seconds). In the same five seconds the light could have circled the globe 37 times. Thunder is seldom heard at distances over 15 miles.

Fear of thunder

Fear of thunder is known as astraphobia.

See also

References

  1. ^ http://weathersavvy.com/Q-lightning1.html
  2. ^ P Graneau, The cause of thunder, 1989 J. Phys. D: Appl. Phys. 22 1083-1094 doi:10.1088/0022-3727/22/8/012

External links

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Translations: Translations for: Thunder

Dansk (Danish)
n. - torden, bulder
v. intr. - tordne, buldre
v. tr. - sige noget med tordnende stemme

Nederlands (Dutch)
donder, gedonder, donderen, denderen, bulderen met iemands idee(ën) goede sier maken

Français (French)
n. - (Météo) tonnerre, fracas, grondement, tonnerre (de)
v. intr. - tonner, faire un bruit de tonnerre (sur), tempêter, passer dans un bruit de tonnerre
v. tr. - hurler, tonner, faire éclater (un tonnerre d'applaudissements)

Deutsch (German)
n. - Donner, Donnern, Donnerwetter
v. - donnern, tosen, brüllen, ein Donnerwetter loslassen

Ελληνική (Greek)
n. - βροντή, μπουμπουνητό, κεραυνός
v. - βροντώ, μπουμπουνίζω, βροντοφωνάζω, μιλώ ή εκφράζομαι έντονα

Italiano (Italian)
tuonare, tuono

idioms:

  • steal a person's thunder    rubare le idee di

Português (Portuguese)
n. - raio (m), trovão (m), trovoada (f), censuras (f pl), estrondo (m)
v. - trovejar

idioms:

  • steal a person's thunder    roubar a idéia de outro

Русский (Russian)
грохотать, греметь, гром

idioms:

  • steal a person's thunder    перехватить инициативу, добиться преимущества, перехватить приоритет

Español (Spanish)
n. - trueno, estruendo
v. intr. - tronar, retumbar
v. tr. - proferir como un trueno, lanzar, fulminar, golpear repetidamente, expresar con aplausos

Svenska (Swedish)
n. - åska, dunder, dån
v. - åska, dundra, dåna, braka

中文（简体） (Chinese (Simplified))
雷, 轰隆声, 雷声, 打雷, 怒喝, 轰隆地响, 轰隆地发出, 厉声发出吼出, 砰然重击

中文（繁體） (Chinese (Traditional))
n. - 雷, 轟隆聲, 雷聲
v. intr. - 打雷, 怒喝, 轟隆地響
v. tr. - 轟隆地發出, 厲聲發出吼出, 砰然重擊

한국어 (Korean)
n. - 우뢰, 고함, 비난
v. intr. - 천둥 치다, 큰 소리를 내다, 탄핵하다
v. tr. - 고함지르다, 발사하다, 큰 소리로 말하다

日本語 (Japanese)
n. - 雷, 雷のような音, とどろき
v. - 雷が鳴る, とどろく, 大声で言う, 激しく非難する

العربيه (Arabic)
‏(الاسم) رعد (فعل) ترعد السماء‏

עברית (Hebrew)
n. - ‮רעם, רעש, זעם‬
v. intr. - ‮רעם, הרעים בקולו‬
v. tr. - ‮רעם, איים, ביקר בחריפות‬

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