5.7 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ball lightning | 5/8 | https://en.wikipedia.org/wiki/Ball_lightning | reference | science, encyclopedia | 2026-05-05T11:04:47.852283+00:00 | kb-cron |
== Direct measurements of natural ball lightning ==
In January 2014, scientists from Northwest Normal University in Lanzhou, China, published the results of recordings made in July 2012 of the optical spectrum of what was thought to be natural ball lightning made by chance during the study of ordinary cloud–ground lightning on the Tibetan Plateau. At a distance of 900 m (3,000 ft), a total of 1.64 seconds of digital video of the ball lightning and its spectrum was made, from the formation of the ball lightning after the ordinary lightning struck the ground, up to the optical decay of the phenomenon. Additional video was recorded by a high-speed (3000 frames/sec) camera, which captured only the last 0.78 seconds of the event, due to its limited recording capacity. Both cameras were equipped with slitless spectrographs. The researchers detected emission lines of neutral atomic silicon, calcium, iron, nitrogen, and oxygen—in contrast with mainly ionized nitrogen emission lines in the spectrum of the parent lightning. The ball lightning traveled horizontally across the video frame at an average speed equivalent of 8.6 m/s (28 ft/s). It had a diameter of 5 m (16 ft) and covered a distance of about 15 m (49 ft) within those 1.64 s. Oscillations in the light intensity and in the oxygen and nitrogen emission at a frequency of 100 hertz, possibly caused by the electromagnetic field of the 50 Hz high-voltage power transmission line in the vicinity, were observed. From the spectrum, the temperature of the ball lightning was assessed as being lower than the temperature of the parent lightning (<15,000 to 30,000 K). The observed data are consistent with vaporization of soil as well as with ball lightning's sensitivity to electric fields.
== Laboratory experiments == Scientists have long attempted to produce ball lightning in laboratory experiments. While some experiments have produced effects that are visually similar to reports of natural ball lightning, it has not yet been determined whether there is any relation. Nikola Tesla reportedly could artificially produce 1.5-inch (3.8 cm) balls and conducted some demonstrations of his ability. Tesla was more interested in higher voltages and powers as well as remote transmission of power; the balls he made were just a curiosity. The International Committee on Ball Lightning (ICBL) held regular symposia on the subject. A related group uses the generic name "Unconventional Plasmas". The last ICBL symposium was tentatively scheduled for July 2012 in San Marcos, Texas but was cancelled due to a lack of submitted abstracts.
=== Wave-guided microwaves === Ohtsuki and Ofuruton described producing "plasma fireballs" by microwave interference within an air-filled cylindrical cavity fed by a rectangular waveguide using a 2.45 GHz, 5 kW (maximum power) microwave oscillator.
=== Water discharge experiments ===
Some scientific groups, including the Max Planck Institute, have reportedly produced a ball lightning-type effect by discharging a high-voltage capacitor in a tank of water.
=== Home microwave oven experiments === Many modern experiments involve using a microwave oven to produce small rising glowing balls, often referred to as plasma balls. Generally, the experiments are conducted by placing a lit or recently extinguished match or other small object in a microwave oven. The burnt portion of the object flares up into a large ball of fire, while "plasma balls" float near the oven chamber ceiling. Some experiments describe covering the match with an inverted glass jar, which contains both the flame and the balls so that they do not damage the chamber walls. (A glass jar, however, eventually explodes rather than simply causing charred paint or melting metal, as happens to the inside of a microwave.) Experiments by Eli Jerby and Vladimir Dikhtyar in Israel revealed that microwave plasma balls are made up of nanoparticles with an average radius of 25 nm (9.8×10−7 inches). The team demonstrated the phenomenon with copper, salts, water and carbon.
=== Silicon experiments === Experiments in 2007 involved shocking silicon wafers with electricity, which vaporizes the silicon and induces oxidation in the vapors. The visual effect can be described as small glowing, sparkling orbs that roll around a surface. Two Brazilian scientists, Antonio Pavão and Gerson Paiva of the Federal University of Pernambuco have reportedly consistently made small long-lasting balls using this method. These experiments stemmed from the theory that ball lightning is actually oxidized silicon vapors (see vaporized silicon hypothesis, below).
=== Short interval lab created ball lightning analogues ===
==== Stable plasma toroid model ==== Although lasting only about 200 milliseconds in a partial atmosphere, the spinning plasma toroid has the appearance of ball lightning, based on observations, computer simulations, and mathematical equations. Spinning plasma toroids can be created by means of high power electric arcs, which may explain ball lightning observations after lightning bolts.
==== Atmospheric plasmoids above a water surface ==== Atmospheric plasmoids lasting up to only 350 microseconds in the visible spectral range (UV-NIR) were created by means of high-voltage discharge above a water surface.
== Proposed scientific explanations == There is at present no widely accepted explanation for ball lightning. Several hypotheses have been advanced since the phenomenon was brought into the scientific realm by the English physician and electrical researcher William Snow Harris in 1843, and French Academy scientist François Arago in 1855.