Thunder

Last updated
For other uses, see Thunder (disambiguation).Not to be confused with lightning.
Thunder is the sound produced by lightning. Lightning 14.07.2009 20-42-33.JPG
Thunder is the sound produced by lightning.
Cumulonimbus clouds often form thunderstorms. Anvil shaped cumulus panorama edit crop.jpg
Cumulonimbus clouds often form thunderstorms.

Thunder is the sound caused by lightning. [1] [2] [3] Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning produces rapid expansion of the air in the path of a lightning bolt. [4] In turn, this expansion of air creates a sonic shock wave, often referred to as a "thunderclap" or "peal of thunder". The scientific study of thunder is known as brontology and the irrational fear (phobia) of thunder is called brontophobia.

Contents

Etymology

The d in Modern English thunder (from earlier Old English þunor) is epenthetic, and is now found as well in Modern Dutch donder (cf. Middle Dutch donre; also Old Norse þorr , Old Frisian þuner, Old High German donar, all ultimately descended from Proto-Germanic *þunraz). In Latin the term was tonare "to thunder". The name of the Nordic god Thor comes from the Old Norse word for thunder. [5]

The shared Proto-Indo-European root is *tón-r̥ or *tar-, also found in Gaulish Taranis . [6]

Cause

The cause of thunder has been the subject of centuries of speculation and scientific inquiry. [7] Early thinking was that it was made by deities, but the ancient Greek philosophers attributed it to natural causes, such as wind striking clouds (Anaximander, Aristotle) and movement of air within clouds (Democritus). [8] The Roman philosopher Lucretius held it was from the sound of hail colliding within clouds. [8]

In the mid-19th century, the accepted theory was that lightning produced a vacuum and that the collapse of that vacuum produced what is known as thunder. [7]

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. [9] [8] The temperature inside the lightning channel, measured by spectral analysis, varies during its 50 μs existence, rising sharply from an initial temperature of about 20,000  K to about 30,000 K, then dropping away gradually to about 10,000 K. The average is about 20,400 K (20,100 °C; 36,300 °F). [10] This heating causes a rapid outward expansion, impacting the surrounding cooler air at a speed faster than sound would otherwise travel. The resultant outward-moving pulse is a shock wave, [11] similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft. Near the source, the sound pressure level of thunder is usually 165 to 180 dB, but can exceed 200 dB in some cases. [12]

Experimental studies of simulated lightning have produced results largely consistent with this model, though there is continued debate about the precise physical mechanisms of the process. [13] [9] Other causes have also been proposed, relying on electrodynamic effects of the enormous current acting on the plasma in the bolt of lightning. [14]

Consequences

The shock wave in thunder is sufficient to cause property damage [7] and injury, such as internal contusion, to individuals nearby. [15] Thunder can rupture the eardrums of people nearby, leading to permanently impaired hearing. [7] Even if not, it can lead to temporary deafness. [7]

Types

Vavrek et al. (n.d.) reported that the sounds of thunder fall into categories based on loudness, duration, and pitch. [7] Claps are loud sounds lasting 0.2 to 2 seconds and containing higher pitches. Peals are sounds changing in loudness and pitch. Rolls are irregular mixtures of loudness and pitches. Rumbles are less loud, last for longer (up to more than 30 seconds), and are of low pitch. [16]

Inversion thunder results when lightning strikes between cloud and ground occur during a temperature inversion; the resulting thunder sounds have significantly greater acoustic energy than from the same distance in a non-inversion condition. In an inversion, the air near the ground is cooler than the higher air; inversions often occur when warm moist air passes above a cold front. Within a temperature inversion, the sound energy is prevented from dispersing vertically as it would in a non-inversion and is thus concentrated in the near-ground layer. [17]

Cloud-to-ground lightning (CG) typically consists of two or more return strokes, from ground to cloud. Later return strokes have greater acoustic energy than the first. [18]

Perception

Gnome-mime-sound-openclipart.svg
Thundercracks
Sample of sharp cracking sounds of thunder heard immediately after nearby lightning strikes
Crack of thunder
A crack of thunder during the sound of falling rain
Problems playing these files? See media help.

The most noticeable aspect of lightning and thunder is that the lightning is seen before the thunder is heard. This is a consequence of the speed of light being much greater than the speed of sound. The speed of sound in dry air is approximately 343 m/s (1,130 ft/s) or 1,236 km/h (768 mph) at 20 °C (68 °F; 293 K). [19]

This translates to approximately 3 s/km (4.8 s/mi); saying "one thousand and one... one thousand and two..." is a useful method of counting the seconds from the perception of a given lightning flash to the perception of its thunder (which can be used to gauge the proximity of lightning for the sake of safety). Thus, take the counted seconds and divide by five, this will produce the distance in miles from the lightning strike. [20]

A very bright flash of lightning and an almost simultaneous sharp "crack" of thunder, a thundercrack, therefore indicates that the lightning strike was very near.

Close-in lightning has been described first as a clicking or cloth-tearing sound, then a cannon shot sound or loud crack/snap, followed by continuous rumbling. [7] The early sounds are from the leader parts of lightning, then the near parts of the return stroke, then the distant parts of the return stroke. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Inversion (meteorology)</span> Deviation from the normal change of an atmospheric property with altitude

In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to an inversion of the air temperature lapse rate, in which case it is called a temperature inversion. Normally, air temperature decreases with an increase in altitude, but during an inversion warmer air is held above cooler air.

<span class="mw-page-title-main">Fog</span> Atmospheric phenomenon

Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Fog can be considered a type of low-lying cloud usually resembling stratus, and is heavily influenced by nearby bodies of water, topography, and wind conditions. In turn, fog affects many human activities, such as shipping, travel, and warfare.

<span class="mw-page-title-main">Lightning</span> Weather phenomenon involving electrostatic discharge

Lightning is a natural phenomenon formed by electrostatic discharges through the atmosphere between two electrically charged regions, either both in the atmosphere or with one in the atmosphere and on the ground, temporarily neutralizing these in a near-instantaneous release of an average of one gigajoule of energy. This discharge may produce a wide range of electromagnetic radiation, from heat created by the rapid movement of electrons, to brilliant flashes of visible light in the form of black-body radiation. Lightning causes thunder, a sound from the shock wave which develops as gases in the vicinity of the discharge experience a sudden increase in pressure. Lightning occurs commonly during thunderstorms as well as other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions. Lightning is an atmospheric electrical phenomenon and contributes to the global atmospheric electrical circuit.

<span class="mw-page-title-main">Thunderstorm</span> Type of weather with lightning and thunder

A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.

<span class="mw-page-title-main">Storm</span> Disturbed state of an astronomical bodys atmosphere

A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning, heavy precipitation, heavy freezing rain, strong winds, wind transporting some substance through the atmosphere such as in a dust storm, among other forms of severe weather.

<span class="mw-page-title-main">Sonic boom</span> Shock wave from flying at the speed of sound

A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear.

<span class="mw-page-title-main">Wind shear</span> Difference in wind speed or direction over a short distance

Wind shear, sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with a change in altitude. Horizontal wind shear is a change in wind speed with a change in lateral position for a given altitude.

<span class="mw-page-title-main">Heat lightning</span> Description of distant cloud to ground lightning

Heat lightning, also known as silent lightning, summer lightning, or dry lightning, is a misnomer used for the faint flashes of lightning on the horizon or other clouds from distant thunderstorms that do not appear to have accompanying sounds of thunder.

<span class="mw-page-title-main">Synoptic scale meteorology</span> 1000-km-order method of measuring weather systems

In meteorology, the synoptic scale is a horizontal length scale of the order of 1,000 km (620 mi) or more. This corresponds to a horizontal scale typical of mid-latitude depressions. Most high- and low-pressure areas seen on weather maps are synoptic-scale systems, driven by the location of Rossby waves in their respective hemisphere. Low-pressure areas and their related frontal zones occur on the leading edge of a trough within the Rossby wave pattern, while high-pressure areas form on the back edge of the trough. Most precipitation areas occur near frontal zones. The word synoptic is derived from the Ancient Greek word συνοπτικός (sunoptikós), meaning "seen together".

<span class="mw-page-title-main">Thundersnow</span> Thunderstorm during which there is snowfall

Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is a thunderstorm in which snow falls as the primary precipitation instead of rain. It is considered a rare phenomenon. It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone. Thermodynamically, it is not different from any other type of thunderstorm, but the top of the cumulonimbus cloud is usually quite low. In addition to snow, graupel or hail may fall as well. The heavy snowfall tends to muffle the sound of the thunder so that it sounds more like a low rumble than the loud, sharp bang that is heard during regular thunderstorms.

<span class="mw-page-title-main">Index of meteorology articles</span>

This is a list of meteorology topics. The terms relate to meteorology, the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting.

<span class="mw-page-title-main">Lightning strike</span> Electric discharge between the atmosphere and the ground

A lightning strike is a lightning event in which the electric discharge takes place between the atmosphere and the ground. Most originate in a cumulonimbus cloud and terminate on the ground, called cloud-to-ground (CG) lightning. A less common type of strike, ground-to-cloud (GC) lightning, is upward-propagating lightning initiated from a tall grounded object and reaching into the clouds. About 25% of all lightning events worldwide are strikes between the atmosphere and earth-bound objects. Most are intracloud (IC) lightning and cloud-to-cloud (CC), where discharges only occur high in the atmosphere. Lightning strikes the average commercial aircraft at least once a year, but modern engineering and design means this is rarely a problem. The movement of aircraft through clouds can even cause lightning strikes.

A skyquake is a phenomenon where a loud booming sound is reported to originate from the sky. The sound may cause noticeable vibration in a building or across a particular area. Those who experience skyquakes typically do not have a clear explanation for what caused them and they are perceived as mysterious.

<span class="mw-page-title-main">Lightning detection</span> Remote observation of lightning strikes

A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location, and space-based systems.

<span class="mw-page-title-main">Atmospheric convection</span> Atmospheric phenomenon

Atmospheric convection is the result of a parcel-environment instability in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day expands the height of the planetary boundary layer, leading to increased winds, cumulus cloud development, and decreased surface dew points. Convection involving moist air masses leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.

<span class="mw-page-title-main">Automated airport weather station</span> Automated sensor suites

Airport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing in the United States and Canada and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings.

<span class="mw-page-title-main">Outline of meteorology</span> Overview of and topical guide to meteorology

The following outline is provided as an overview of and topical guide to the field of Meteorology.

<span class="mw-page-title-main">Dry thunderstorm</span> Thunderstorm where little to no precipitation reaches the ground

A dry thunderstorm is a thunderstorm that produces thunder and lightning, but where most of its precipitation evaporates before reaching the ground. Dry lightning refers to lightning strikes occurring in this situation. Both are so common in the American West that they are sometimes used interchangeably.

<span class="mw-page-title-main">Distribution of lightning</span>

The distribution of lightning, or the incidence of individual strikes, in any particular place is highly dependent on its location, climate, and time of year. Lightning does have an underlying spatial distribution. High quality lightning data has only recently become available, but the data indicates that lightning occurs on average 44±5 times every second over the entire Earth, making a total of about 1.4 billion flashes per year.

<span class="mw-page-title-main">Glossary of meteorology</span> List of definitions of terms and concepts commonly used in meteorology

This glossary of meteorology is a list of terms and concepts relevant to meteorology and atmospheric science, their sub-disciplines, and related fields.

References

  1. ↑ "Severe Weather 101: Lightning Basics". nssl.noaa.gov. Retrieved October 23, 2019.
  2. ↑ "Thunder Facts". factsjustforkids.com. Retrieved October 23, 2019.
  3. ↑ "The Sound of Thunder". weather.gov. Retrieved October 23, 2019.
  4. ↑ "What Causes Lightning and Thunder?". NOAA. 2022.
  5. ↑ "thunder". Oxford English Dictionary (2 ed.). Oxford, England: Oxford University Press. 1989.
  6. ↑ Matasovic, Ranko. Etymological Dictionary of Proto Celtic. Leiden, The Netherlands: Brill. 2009. p. 384. ISBN   978-90-04-17336-1
  7. 1 2 3 4 5 6 7 8 Vavrek, R. J.; Kithil, R.; Holle, R. L.; Allsopp, J.; Cooper, M. A. (17 July 2006) [4 April 2006]. "Section 6.1.8: The Science of Thunder". National Lightning Safety Institute. Archived from the original on 17 July 2006. Retrieved 11 June 2022.
  8. 1 2 3 Heidorn, K. C. (1999). Thunder: Voice of the heavens. Retrieved from http://www.islandnet.com/~see/weather/elements/thunder1.htm
  9. 1 2 Rakov, Vladimir A.; Uman, Martin A. (2007). Lightning: Physics and Effects. Cambridge, England: Cambridge University Press. p. 378. ISBN   978-0-521-03541-5.,
  10. ↑ Cooray, Vernon (2003). The lightning flash . London: Institution of Electrical Engineers. pp.  163–164. ISBN   978-0-85296-780-5.
  11. ↑ "Thunder". Encyclopædia Britannica. Archived from the original on 2008-06-07. Retrieved 2008-09-12.
  12. ↑ "Ultimate Sound Pressure Level Decibel Table" . Retrieved 2020-12-13.
  13. ↑ MacGorman, Donald R.; Rust, W. David (1998). The Electrical Nature of Storms. Oxford University Press. pp. 102–104. ISBN   978-0195073379. Archived from the original on 2014-06-28. Retrieved 2012-09-06.
  14. ↑ P Graneau (1989). "The cause of thunder". J. Phys. D: Appl. Phys. 22 (8): 1083–1094. Bibcode:1989JPhD...22.1083G. doi:10.1088/0022-3727/22/8/012. S2CID   250836715.
  15. ↑ Fish, Raymond M (2021). "Thermal and mechanical shock wave injury". In Nabours, Robert E (ed.). Electrical injuries: engineering, medical, and legal aspects. Tucson, AZ: Lawyers & Judges Publishing. p.  220. ISBN   978-1-930056-71-8.
  16. ↑ "Thunder Facts". Fast Facts for Kids. 2022.
  17. ↑ Dean A. Pollet and Micheal M. Kordich (2013-04-08). "User's guide for the Sound Intensity Prediction System (SIPS) as installed at the Naval Explosive Ordnance Disposal Technology Division (Naveodtechdiv)" (PDF). Systems Department February 2000. dtic.mil. Archived from the original on April 8, 2013.
  18. ↑ "Lightning Types". NOAA National Severe Storms Laboratory. 2022.
  19. ↑ Handbook of Chemistry and Physics, 72nd edition, special student edition. Boca Raton: The Chemical Rubber Co. 1991. p. 14.36. ISBN   978-0-8493-0486-6.
  20. ↑ "Understanding Lightning: Thunder". National Weather Service. 2022.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.