thunder

1. The crashing or booming sound produced by rapidly expanding air along the path of the electrical discharge of lightning.
2. A sound that resembles or suggests thunder.

1. To produce thunder.
2. To produce sounds like thunder.
3. To utter loud, vociferous remarks or threats.

To express violently, commandingly, or angrily; roar.

[Middle English, from Old English thunor.]

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.

noun

An earsplitting, explosive noise: bang, blast, boom, roar. See sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.

verb

To make an earsplitting explosive noise: bang, blast, boom, roar. See sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.

When a stroke of lightning passes through the atmosphere, the air becomes intensely hot, perhaps to 30 000 °C. The violent expansion thus caused makes a shock-wave heard as thunder.

The noise created when air rushes back into a region from which it has been expelled by the passage of lightning.

Thunder may indicate a loud knocking at the door of the dreamer's conscious mind to force the dreamer to pay attention and to learn. If accompanied by lightning bolts, inspiration and enlightenment may be indicated.

For other uses, see Thunder (disambiguation).

Thunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, it can range from a sharp, loud crack to a long, low rumble (brontide). The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a bolt of lightning. In turn, this expansion of air creates a sonic shock wave which produces the sound of thunder.

Thunder A short sample of a clap of thunder Problems listening to this file? See media help.

Contents 1 Cause 2 Etymology 3 Calculating distance 4 See also 5 References 6 External links

Cause

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. 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, ^[2] 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.^[3]

Etymology

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

The shared Proto-Indo-European root is *tón-r̥ or *tar-, also found Gaulish Taranis and Hittite Tarhunt.

See also Thursday (Old English Þunresdæg Day of Thor).

Fear of thunder is known as ceraunophobia.

Calculating distance

A flash of lightning, followed after some seconds by a rumble of thunder is, for many people, the first illustration of the fact that sound travels more slowly than light. 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 dry air is approximately 343 m/s or 1,127 feet per second or 768 mph (1,236 km/h) at 68°F (20 °C). ^[4] The speed of light is high enough that it can be taken as infinite in this calculation. Therefore, the lightning is approximately one kilometer distant for every 2.9 seconds (or one mile for every 4.6 seconds). In the same five seconds the light could have travelled the same distance as circling the globe 37 times. Thunder is seldom heard at distances over 24 kilometers (15 miles). A flash of lightning and a simultaneous sharp "clap!" of thunder, a thunderclap, therefore indicates that the lightning strike was very near.

See also

• Thunderstorm
• Thunderbolt
• Lightning
• The Castle Thunder sound effect
• List of thunder gods
• Thunder gods category

References

1. ^ Lightning?
2. ^ "Thunder". Encyclopædia Britannica. http://www.britannica.com/EBchecked/topic/594339/thunder. Retrieved on 2008-09-12. 
3. ^ P Graneau, The cause of thunder, 1989 J. Phys. D: Appl. Phys. 22 1083-1094 doi:10.1088/0022-3727/22/8/012
4. ^ See, for example, page 14-36 of Handbook of Chemistry and Physics, 72nd edition, special student edition. Boca Raton: The Chemical Rubber Co.. 1991. ISBN 0-8493-05625-9. 

External links

• The science of thunder

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

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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