Ball lightning

from Wikipedia, the free encyclopedia

As ball lightning is a scientifically confirmed spherical luminous phenomenon usually referred to in the vicinity of a thunderstorm . Models and demonstration experiments from the field of physics only come close to this phenomenon , which is described by eyewitnesses , in some aspects. Attempts at explanations include hallucinations .

description

Globe of Fire Descending into a Room by Dr. G. Hartwig
Representation of a ball lightning from the 19th century

Experts and laypeople have long been collecting and evaluating eyewitness reports. According to eyewitnesses, the rare phenomena appear suddenly, outdoors and also in closed rooms, mostly near the ground. The phenomena are described as floating, self-luminous and opaque light objects. They do not radiate heat and come in numerous colors and sizes. The shape is described as spherical ( spherical ), egg-shaped, or rod-like.

The mobility of these phenomena is characteristic of the description. They often change their direction within two to eight, a maximum of 30 seconds, apparently not carried by the wind, but oriented towards visible objects. According to eyewitness reports, they penetrate even solid obstacles unchanged and often without leaving any traces, and rain falls through unaffected. Some witnesses report sparks or an end with a loud bang, which is said to have caused injuries and damage.

Some descriptions are very similar to those of other phenomena such as UFOs or foo fighters .

Causes and experiments

state of research

Despite the efforts of experts from various disciplines, such as meteorologists , electrical engineers , physicists and chemists, no uniform, scientifically recognized explanation for the various observations and reports has been found. A particular challenge is to combine the storage of energy necessary for the continuous glow with the ease of movement.

Experiments with artificially generated lightning

Nikola Tesla was the first to generate high-energy artificial lightning and reports in his recordings of ball lightning in his laboratory. Later experimenters were unable to produce anything with lightning that was particularly similar to the behavior expected according to eyewitness reports.

Silicon clouds

A hypothesis presented by John Abrahamson and James Dinniss in New Zealand in 2000 postulates that ball lightning is non-electrical in nature, but is caused by lightning strikes into the ground. Here will silica sand or diatomaceous earth in silicon and oxygen disassembled. While the oxygen in the ground reacts with carbon, the silicon emerges from the lightning duct as vapor or aerosol and is slowly oxidized by atmospheric oxygen, which makes it glow. The silicon particle cloud is said to be able to assume a spherical shape through self-organization due to its charge. It is therefore possible that they will come together again after penetrating a small opening.

This hypothesis was tested in Brazil at the Universidade Federal de Pernambuco by Antonio Pavão and Gerson Paiva by electrically evaporating silicon wafers and igniting the silicon-air mixture by spark discharge. The color, temperature and lifespan (8 seconds) of the ping-pong ball-sized silicon vapor balls corresponded to the testimony of witnesses, insofar as they are exact for a rare short-term phenomenon. A scientific report on this was published in 2007 in the Physical Review Letters .

In 2012, this hypothesis was corroborated by the accidental observation of a ball lightning using a spectrometer. During a thunderstorm, a ball lightning with a diameter of 5 m, which covered about 15 m in 1.6 seconds, was observed and recorded by Chinese scientists. In the spectrum of the ball lightning, silicon, iron and calcium could be detected, all elements that were also abundant in the soil.

Impact in puddles of water

Another hypothesis comes from the German plasma physicist Gerd Fußmann from Berlin's Humboldt University. In 2008 he used a very simple experimental setup to create a luminous phenomenon that is similar to the description of a ball lightning. He filled a vessel with water, inserted two electrodes and applied a voltage of 5 kV for a fraction of a second. For about half a second, a structure emerged that he interpreted as a ball lightning. From this he concluded that ball lightning in nature could result from normal lightning strikes in puddles of water.

His work is based on the one in which he was involved in 2006 as head of the plasma physics working group at the Garching Max Planck Institute for Plasma Physics (IPP) and the Berlin Humboldt University (HUB). At that time, the scientists created glowing, ball-lightning-like plasma balls above a surface of water, which had a lifespan of just under half a second and a diameter of 10 cm to 20 cm. Two electrodes were immersed in a beaker filled with salt water , one electrode being isolated from the surrounding water by a clay tube (which protruded slightly from the surface of the water). If a high voltage of 5 kV was applied via a capacitor battery of 0.5 mF, a current of up to 60 amperes flowed through the water for 0.15 seconds. A flashover from the water caused the current to enter the clay tube, and the water it contained evaporated. After the current pulse, a glowing plasmoid made of ionized water molecules appeared.

Standing waves and burls

Another hypothesis was put forward in 1955 by the Russian physicist Pyotr Kapiza . He calculated the lifespan of a nuclear explosion cloud to the dimensions assumed by ball lightning and obtained a lifespan of less than 10 milliseconds for a fireball with a diameter of 10 cm. Since ball lightning is usually observed for several seconds, he came to the conclusion that they have to be fed externally and that an internal reaction of any kind is not sufficient for the energy requirement. He then developed the hypothesis that standing electromagnetic waves develop between heaven and earth during a thunderstorm and that ball lightning occurs at the antinodes. However, Kapiza did not address the problem that there are a number of antinodes and what conditions make a certain antinode to ball lightning. In order to create a place of preferred energy output, the gas located there must be at least weakly ionized (conductive) compared to the ambient air and it is unclear how such an initial ionization can develop. A hot air bubble is a theoretical example, because the ionization of air increases with temperature. If such an air bubble received more energy as a result, it would lead to a further increase in temperature and thus to a self-swaying process.

Peter Handel expanded the hypothesis with the suggestion of an atmospheric measles . If the volume of a measles is large enough (several cubic kilometers), enough molecules could be excited into an excited state by pumping alone (which in the case of small measles usually leads to the immediate dissipation of the energy). Handel has shown that there are soliton solutions within the maser, that is, a stable standing wave in the nonlinear medium, the energy of which is sustained by the maser for a period of time.

The emergence and the movement of the ball lightning would be tied to the place of the energy release, therefore, unlike the normal plasma, they would not rise and would be insensitive to wind. If the building materials of buildings are permeable to microwaves, which is usually the case, such ball lightning could penetrate them.

Experiments carried out by Ohtsuki and Ofuruton with powerful microwave transmitters yielded plasma balls with comparable dimensions and lifetimes, the balls could move against the wind and apparently penetrate a 3 cm thick ceramic plate, see section Artificial Effects .

Electromagnetic knot

AF Ranada (Madrid) is based on a topological model, a so-called electromagnetic node. An electromagnetic knot is defined as the vacuum solution of Maxwell's equations with the property that all electric and magnetic field lines are closed. According to this hypothesis, the volume of the ball lightning does not consist entirely of plasma, but of interlocking plasma tubes that stabilize each other magnetically and hydrodynamically and have properties with a service life of around 10 s and a net radiation of around 100 W with a total energy of around 20 kJ without external energy supply, as could be shown by appropriate electrodynamic model calculations based on the Alfvén and Maxwell equations. The main part of the energy is not stored by the plasma of the lightning discharge, but as magnetic field energy, with magnetic flux densities of 0.5 T to 2 T being assumed.

More physical hypotheses

There are many other hypotheses: high-current discharges, with which small (<1 cm) jumping fireballs arise, the formation of other ignitable gases or aerosols (so-called diffusive combustion) or the use of esoteric energy sources.

In all the experiments described, it remains unclear and unproven whether the spherical structures produced have anything to do with the lightning bolts described by eyewitnesses.

Physiological explanations

There are researchers who are of the opinion that the observed ball lightning is only an optical illusion. If the eye is strongly blinded for a short time, a light effect can be seen for a few seconds. Moving your eyes can give the impression that a ball of light is flying through the room. This assumption is contradicted by frequent reports that ball lightning was not extremely bright and could be observed for an untypically long time for lighting effects.

Scientists at the University of Innsbruck suspect that the ball lightning bolts described are impressions generated by the brain (so-called phosphenes ). These hallucinations are said to be caused by the electromagnetic fields when lightning strikes, by stimulating the neurons in the brain.

Artificial Effects

Other effects can be generated with a permanent supply of energy from microwaves . Japanese researchers crossed the beams of powerful magnetrons (2.45 GHz, 5 kW) in order to generate an electric field strength sufficient to ignite a gas discharge in the open air, away from the sources, i.e. apparently floating. This plasma ball was a suitable size and light emission and could apparently penetrate a ceramic plate without damaging it. In fact, only the microwaves penetrated the plate and ignited another discharge behind it. The plasma went out immediately after switching off the microwave.

References

  1. ↑ Example in Rolf Froböse: When frogs fall from the sky. Wiley-VCH, 2007, p. 43.
  2. ↑ Quarks. - The myth of ball lightning. ( Memento of July 3, 2009 in the Internet Archive ). WDR broadcast on June 30, 2009.
  3. ↑ Hazel Muir: Ball lightning scientists remain in the dark. At: newscientist.com. December 20, 2001, accessed September 18, 2004.
  4. ↑ Nikola Tesla, Colorado Springs Notes, pp. 368-370.
  5. ↑ John Abrahamson, James Dinniss: Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil . In: Nature . No. 403 , 2000, pp. 519-521 , doi : 10.1038 / 35000525 . For the hypothesis of Abrahamson and Dinniss see also: 02/04/2000 - Climate and Weather: The Riddle of Ball Lightning. ( Memento from June 10, 2010 in the Internet Archive ).
  6. ↑ On the experimental proof of silicon vapor balls: How to make ball lightning. From: Wissenschaft.de on January 11, 2007, accessed on September 12, 2019.
  7. ^ Gerson Silva Paiva, Antonio Carlos Pavão: Production of Ball-Lightning-Like Luminous Balls by Electrical Discharges in Silicon . In: Physical Review Letters . tape 98 , no. 4 , 2007, p. 048501 , doi : 10.1103 / PhysRevLett.98.048501 .
  8. ↑ Jianyong Cen, Ping Yuan, Simin Xue: Observation of the Optical and Spectral Characteristics of Ball Lightning . In: Physical Review Letters . tape 112 , no. 3 , 2014, p. 035001 , doi : 10.1103 / PhysRevLett.112.035001 .
  9. ↑ Philip Ball: Focus: First Spectrum of Ball Lightning. 2014.
  10. ↑ Website of the Max Planck Institute for Plasma Physics: Ball lightning - can be generated in the laboratory? accessed on January 5, 2020.
  11. ↑ Frank Thadeusz: Meteorology: Fireball from the puddle. At: spiegel.de. August 11, 2008, accessed September 18, 2014.
  12. ↑ Rolf H. Latussek: Mysterious ball lightning really does exist. At: welt.de. August 12, 2008, accessed September 18, 2014.
  13. ↑ Ball lightning in the laboratory. ( Memento of March 3, 2010 in the Internet Archive ). At: ipp.mpg.de. Report of the IPP working group on plasma physics.
  14. ↑ PL Kapitza: On the nature of ball-lightning. Translation from Russian. In: Collected Papers of Kapitza. Vol. 2. Pergamon Press, London 1965, pp. 776-780.
  15. ↑ PH Handel: Maser-Caviton Ball Lightning Mechanism. Proc. VIII Int. Conf. on Atmospheric Electricity, Institute of High Voltage Research, Uppsala University Press, Uppsala, Sweden, 1988, pp. 177-182.
  16. ↑ a b Y. H. Ohtsuki , H. Ofuruton: Plasma fireballs formed by microwave interference in air . In: Nature . No. 350 , 1991, pp. 139-141 , doi : 10.1038 / 350139a0 .
  17. ↑ AF Ranada, M. Soler, JL Trueba: ball lightning as a force-free magnetic knot. In: Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics. Volume 62, Number 5 Pt B, November 2000, pp. 7181-7190, PMID 11102074 .
  18. ↑ J. Peer, A. Kendl: Transcranial stimulability of phosphenes by long lightning electromagnetic pulses . In: Physics Letters A . tape 374 , no. 29 , 2010, p. 2932-2935 , doi : 10.1016 / j.physleta.2010.05.023 .
  19. ↑ Harald Pokieser, Manfred Christ: UNIVERSUM: The weapons of the gods. ORF 1995, 50 minutes.

literature

  • Max Toepler: On the dependence of the character of a continuous electrical discharge in atmospheric air on the amount of electricity continuously supplied to the discharge space, together with an appendix on the knowledge of ball lightning. Annalen der Physik 307 (7), 1900, pp. 560-635.
  • K. Berger: Ball lightning and lightning research. Naturwissenschaften 60 (11), 1973, pp. 485-492, ISSN  0028-1042 .
  • Mark Stenhoff: Ball Lightning: An Unsolved Problem in Atmospheric Physics. Springer, 1999.
  • A. Kendl: Ball lightning: a phenomenon between physics and folklore. Skeptiker 14, 2/2001, pp. 65-69, ISSN  0936-9244 .
  • U. Ebert: Ball lightning without plasma? (PDF; 168 kB) Physik Journal 6, 2007, pp. 18–19, ISSN  1617-9439 .

Web links

Wiktionary: Kugelblitz  - explanations of meanings, word origins, synonyms, translations
Commons : Kugelblitz  - album with pictures, videos and audio files