Thunder is the cracking, grinding, or rolling sound made by lightning during a thunderstorm .
Thunder is caused by the sudden expansion of the air caused by the extreme rise in temperature when lightning passes through. This process can only be started when there is sufficient humidity . The air expands at a speed above the speed of sound and breaks the sound barrier . A pressure wave is generated from compressed air molecules, which spreads at supersonic speed and can be heard as a loud bang.
The intensity or volume of this bang decreases with the distance to the place of origin, since the energy of the pressure wave is distributed over a larger area. While a "bang" is only perceptible in the immediate vicinity (up to 5 km), the noise extends into a continuous whispering or rolling, especially in the case of lightning further away, whereby no volume peak can be detected. This "stretching" of the pressure wave is done by dispersion ; H. Different speeds of sound of the individual frequency components of the bang, which thus reach the observer at different times, due to the refraction of pressure changes and temperature changes that result in different densities and thus different speeds of sound, and winds in the air through which the sound components deflect and mix differently. Exceptions, however, due to unusually violent discharges in the atmosphere, are also possible, so that a clear bang can still be heard over long distances. If the distance to the lightning is too great, the thunder will no longer be perceived; see weather lights . During typical Central European thunderstorms, the thunder can be heard about 5 to 20 km away (depending on the wind direction, background noise, temperature and humidity, terrain and surface, buildings, forest cover), which corresponds to a time span between lightning and thunder of about 15 to 60 seconds .
This bang is accompanied by other noises that are nothing more than an echo , i.e. an echo, the actual pressure wave. This can be reflected by clouds, mountain slopes and buildings, so that under favorable conditions the bang, in a weakened form, is repeated several times in succession. If the observer is between the point of origin and a suitable reflector, the thunder can even be perceived from two different directions. As a rule, it often appears not only to come directly from lightning, but also stretched out from its surroundings, giving it a broad and threatening character.
Another reason for an extended bang, i.e. a longer roll, is the course of the lightning bolt, for example if it extends several kilometers away from the observation point. This pressure wave is generated at every point in the lightning canal, so that it takes more time from the more distant part of the lightning to reach the observer. In the vernacular, thunder means precisely this interplay of bang, rolling and reverberation.
Sometimes the bang is preceded by a roll. This happens when part of the lightning bolt is closer to the observer than the rest or the actual lightning bolt. This much weaker pressure wave reaches the observer one to several seconds before the actual bang, depending on how much the lightning is curved. In order for this phenomenon to occur, the lightning channel must move horizontally away from the observer by at least 150 m, otherwise the time between roll and bang would be too short, and both noises would coincide perceptually. Example: Bending the lightning channel about 340 meters away from the observer causes the roll to sound about a second earlier than the actual bang.
Determination of the distance to the place of origin
The distance of a thunderstorm from the observer's location can be estimated quite easily:
With the speed of sound of around 340 meters per second, with which the pressure wave approaches the thunder, there is a distance of 340 m for every counted second between the perception of the lightning and the thunder. The number of seconds between the flashing of lightning and the perception of its thunder multiplied by 340 m gives the distance to the thunderstorm in meters. For example, a thunderstorm is approximately 3.4 kilometers away if the time between lightning and thunder is ten seconds.
Alternatively, the number of seconds counted can be divided by 3, the result is roughly the distance in km. This calculation is only correct for a speed of sound of 1/3 km / s = 333.33 m / s, so that the actual distance between the thunderstorm may be slightly larger.
In principle, this method can only be used if the thunder noise can be clearly assigned to a lightning phenomenon. If the thunders of different and differently distant lightning bolts overlap with several discharges in quick succession, it is no longer possible to reliably assign the thunder.
Natural phenomena such as thunder, storm winds and rain gave early peoples the idea of a heavenly deity who, as the originator, was supposed to provide an explanation for what could not be explained otherwise. In the cosmogonic myths, everyday experiences are used as models for the cosmic order. Typical is the personification of ominous and threatening thunder as a partial aspect of the god of heaven, as a subordinate deity in a polytheistic religion or as a powerful being in a world of faith determined by natural forces . In medieval Europe was in the woods or when plowing in the field found, Stone Age as artefacts, stone axes and arrowheads from flint , a magical significance awarded. The god of thunder sent stone axes down as lightning, which is why they were called "thunderbolt". Buried under the house, walled up in walls or hidden in the attic, similar to amulets , they should keep mischief away.
The Christian Tatars used the same designation tängere-babaj ( tängere from tengri , “god”, babaj , “age”) for thunder and for the god of heaven , and told a variant of the popular myth that the god of thunder was in pursuit of the devil ( shaitan ) hurried across the sky in a horse-drawn chariot and made the thunder with the chariot wheels. The idea probably came to Central Asia with the Christianization via the Russians, because the Old Testament prophet Elijah already traveled across the heavens with a fiery chariot and horses.
If the thunder rumbles, then speaks heaven. The Chinese and Mongols attribute this truism of popular belief to a sentence by Confucius (around 551–479 BC). The Chinese prehistoric man Pangu produces thunder with his voice. In many cultures, the sky god is considered the charioteer. The easily comprehensible image stands for the ruler of fate, the one who determines in advance.
In the mythology of the North American Indians , nature is inspired by spirits, some worship thunder as a thunderbird. Likewise, the Tungus who live in the Arctic Circle in North Asia explain the thunder with the sound of a giant bird in flight. Local shamans carve the bird out of wood and plant the figure on a long pole so that it may keep them from harm on their ceremonial journey to heaven. The bird is said to have cut trees felled by lightning with its stone claws. Among the Siberian Samoyed , the thunderbird appeared as a wild duck, whose sneezing condescends a shower of rain. Protector of the shamans, thunderbird and iron bird are often related ideas. The biblical Elijah appears in the mythical stories of the Teleuts as an eagle, which causes the thunder and is equated with the sky god tengeri purkan , who is said to live in the twelfth layer of the sky.
In some regions of Central Asia, the thunder appears as a dragon flying through the air, which in the Mongols has wings and a body made of fish scales. It causes a rumble of thunder with its voice and lightning when it hits its tail. If it flies low enough, people can see it. This fits another idea that a fish swimming in the clouds causes the thunder with its scales and the wind with its tail. The Central Asian thunder dragon can live on a high mountain in winter, where it creates the frost and ice fields in the valleys with its breath, it can live in a dense forest in winter and cause fog there or swim in the sea during the cold season.
The idea of the dragon causing thunder apparently came from China to the northern regions. The Chinese word for "dragon" and "thunder", lun , became lu or ulu for "thunder" in some languages . According to a Mongolian tale, the devil produces thunder when he turns into a young camel and goes into the water. Steam then comes out of its mouth, which rises to a dark cloud and takes the camel up with it. When the cloud tips on its side, the camel falls, grinds its teeth, spits fire and creates thunder. On the back of another camel, three beings ride across the sky, one beats a drum and causes thunder, the second waves a white cloth, from which lightning flashes and the third tears the cattle by the bridle, which is why water runs from its mouth, which as Rain comes down.
From Turkestan comes the conception of an old woman who shakes out skins in the sky and thus causes thunder. In Iranian mythology , the same old woman shakes out her pants. In many parts of Central Asia there was a cult of thunder, in which people made a sacrifice when a thunderstorm was approaching by spilling milk in different ways.
In the ancient Babylonian religion , Ištar was a planetary goddess, creator goddess and also embodied fertility, sexual desire and war. As a storm goddess, she brought rain and thunder. In this role, the lion was part of her portrayal, probably because of its loud roar. The Mesopotamian weather god Adad has been known under the name Iškur of small sculptures ( glyptics ) since the Akkadian period (end of the 3rd millennium BC ). Usually he stands on a two-axle wagon pulled by a lion kite and brandishes a whip, the crack of which symbolizes thunder and the twitching movement symbolizes lightning.
The mighty thunder god Zeus of Greek mythology defeated the evil titan Kronos , who devoured all of his children except Zeus. In addition, he freed the one-eyed Cyclops, feared as thunderstorm demons, and received thunder and lightning as a thank you, which became his weapons. Zeus' Roman counterpart was the supreme god Jupiter , who was worshiped as a thunderstorm god by his nickname Jupiter Tonans ("the thundering Jupiter").
In contrast to Jupiter, the North Germanic Thor was not a father of gods, but primarily a god of thunder. Its alternative name Donar is derived from the Latin tonare ("thunder"), with the Norwegian tor also meaning "thunder". The most powerful attribute of Thor is his hammer called Mjolnir . When lightning struck, Thor had thrown his shiny metallic weapon down from above for the northern Germans. The rumble of thunder meant that Thor was rolling across the sky in a chariot pulled by billy goats. Because he was a kind god, many Norwegians still bear his name today.
Several things in common connect Thor with the ancient Indian supreme god Indra . He lives on the summit of the world mountain Meru and is characterized by his weapon, the thunderbolt vajra , as the god of thunder and storm. According to the Puranas , Indra pulled across the sky on a horse-drawn cart ( ratha ), which was driven by the charioteer Matali.
The religions of the ancient Central American civilizations offered detailed explanations for every natural phenomenon, the cause of which was seen in the work of a god. Among the Aztecs , Tlaloc was a god of rain and fertility, who was also associated with thunder. Its equivalent in the Mayan religion was called Chaac . Many sacrifices were made to him. Other Mayan thunder gods were Ah Peku and Coyopa, the ruler of the rumble of thunder. In the mythology of the South American Inca there was the weather god Illapa, who was also responsible for thunder, and the lightning and thunder god Apocatequil.
In the African cosmogony , the creation of the cosmos plays only a subordinate role, but it is more about how the first humans established a place on earth. The West African Songhai attribute the Zin (derived from the Muslim Djinn ), the first God-created beings to rule over water, land and wind. Later came Dongo, who became the spirit of thunder and the heavenly ruler. The Ashanti have several hundred Abosom, lower deities who represent waters and trees. The best known among them is the river god Tano, who with his attribute, an ax, was probably earlier a god of thunder.
While rain and fertility cults are widespread in Africa, the personified thunder is relatively rare. Shango is the god of thunder in the religion of the Yoruba in Nigeria. He is usually depicted with three heads and a double ax . The Venda in South Africa know a creator god called Raluvhimba, who appears in all natural phenomena such as storm, rain and thunder. A story by the Yeye, an ethnic group in Botswana , is in the manner characteristic of African origin myths about a creator god who was initially present, who later - disappointed by the people - withdrew to the sky, where he was occasionally seen in a bright light and his voice can be heard with the rumble of thunder.
- ↑ H. Aaftink, P. Hasse, A. Weiß .: Living with lightning - Frequently asked questions about lightning and thunderstorms. DEHN Germany., February 28, 2013, accessed on September 9, 2017 (archive) .
- ↑ Claudia Sachße: With the battle ax against jaundice? Archaeologica as a medicine in historical times. In: F. Falkenstein, S. Schade-Lindig, A. Zeeb-Lanz (eds.): Kumpf, Kalotte, Pfeilschaftglätter. Two lives for archeology. Commemorative publication for Annemarie Häußer and Helmut Spatz. (International Archeology - Studia honoraria 27) Leidorf, Rahden (Westfalen) 2008, pp. 227–244, here p. 227
- ↑ Uno Harva : The religious ideas of the Altaic peoples . FF Communications N: o 125. Suomalainen Tiedeakatemia, Helsinki 1938, pp. 148-150
- ↑ Uno Harva, pp. 205-209, 212, 217
- ↑ Daniel Schwemer: The type of the weather god in the ancient Orient. WiBiLex
- ↑ Karl Kerényi : The mythology of the Greeks. Volume 1. The stories of gods and mankind. Deutscher Taschenbuch Verlag, Munich 1977, p. 25
- ↑ Matali, Charioteer of Indra. Indian Net Zone
- ↑ Pierre Grimal (ed.): Myths of the peoples. Fischer, Frankfurt 1977, Volume 3, pp. 263f, 266
- ↑ Harold Scheub: A Dictionary of African Mythology. The Mythmaker as Storyteller. Oxford University Press, New York 2000, pp. 217, 250