6.2 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ball lightning | 6/8 | https://en.wikipedia.org/wiki/Ball_lightning | reference | science, encyclopedia | 2026-05-05T11:04:47.852283+00:00 | kb-cron |
=== Vaporized silicon hypothesis === This hypothesis suggests that ball lightning consists of vaporized silicon burning through oxidation. Lightning striking Earth's soil could vaporize the silica contained within it, and somehow separate the oxygen from the silicon dioxide, turning it into pure silicon vapor. As it cools, the silicon could condense into a floating aerosol, bound by its charge, glowing due to the heat of silicon recombining with oxygen. An experimental investigation of this effect, published in 2007, reported producing "luminous balls with lifetime in the order of seconds" by evaporating pure silicon with an electric arc. Videos and spectrographs of this experiment have been made available. This hypothesis got significant supportive data in 2014, when the first ever recorded spectra of natural ball lightning were published. The theorized forms of silicon storage in soil include nanoparticles of Si, SiO, and SiC. Matthew Francis has dubbed this the "dirt clod hypothesis", in which the spectrum of ball lightning shows that it shares chemistry with soil.
=== Electrically charged solid-core model === In this model, ball lightning is assumed to have a solid, positively charged core. According to this underlying assumption, the core is surrounded by a thin electron layer with a charge nearly equal in magnitude to that of the core. A vacuum exists between the core and the electron layer containing an intense electromagnetic (EM) field, which is reflected and guided by the electron layer. The microwave EM field applies a ponderomotive force (radiation pressure) to the electrons preventing them from falling into the core.
=== Microwave cavity hypothesis === Pyotr Kapitsa proposed that ball lightning is a glow discharge driven by microwave radiation that is guided to the ball along lines of ionized air from lightning clouds where it is produced. The ball serves as a resonant microwave cavity, automatically adjusting its radius to the wavelength of the microwave radiation so that resonance is maintained. The Handel Maser-Soliton theory of ball lightning hypothesizes that the energy source generating the ball lightning is a large (several cubic kilometers) atmospheric maser. The ball lightning appears as a plasma caviton at the antinodal plane of the microwave radiation from the maser. In 2017, Researchers from Zhejiang University in Hangzhou, China, proposed that the bright glow of lightning balls is created when microwaves become trapped inside a plasma bubble. At the tip of a lightning strike reaching the ground, a relativistic electron bunch can be produced when in contact with microwave radiation, the latter ionizes the local air and the radiation pressure evacuates the resulting plasma, forming a spherical plasma bubble that stably traps the radiation. Microwaves trapped inside the ball continue to generate plasma for a moment to maintain the bright flashes described in observer accounts. The ball eventually fades as the radiation held within the bubble starts to decay and microwaves are discharged from the sphere. The lightning balls can dramatically explode as the structure destabilizes. The theory could explain many of the strange characteristics of ball lightning. For instance, microwaves are able to pass through glass, which helps to explain why balls could be formed indoors.
=== Soliton hypothesis ===
Julio Rubinstein, David Finkelstein, and James R. Powell proposed that ball lightning is a detached St. Elmo's fire (1964–1970). St. Elmo's fire arises when a sharp conductor, such as a ship's mast, amplifies the atmospheric electric field to breakdown. For a globe the amplification factor is 3. A free ball of ionized air can amplify the ambient field this much by its own conductivity. When this maintains the ionization, the ball is then a soliton in the flow of atmospheric electricity. Powell's kinetic theory calculation found that the ball size is set by the second Townsend coefficient (the mean free path of conduction electrons) near breakdown. Wandering glow discharges are found to occur within certain industrial microwave ovens and continue to glow for several seconds after power is shut off. Arcs drawn from high-power low-voltage microwave generators also are found to exhibit afterglow. Powell measured their spectra, and found that the after-glow comes mostly from metastable NO ions, which are long-lived at low temperatures. It occurred in air and in nitrous oxide, which possess such metastable ions, and not in atmospheres of argon, carbon dioxide, or helium, which do not. The soliton model of a ball lightning was further developed. It was suggested that an instance of ball lightning is based on spherically symmetric nonlinear oscillations of charged particles in plasma – the analogue of a spatial Langmuir soliton. These oscillations were described in both classical and quantum approaches. It was found that the most intense plasma oscillations occur in the central regions of a ball lightning. It is suggested that bound states of radially oscillating charged particles with oppositely oriented spins – the analogue of Cooper pairs – can appear inside a ball lightning. This phenomenon, in its turn, can lead to a superconducting phase in a ball lightning. The idea of the superconductivity in a ball lightning was considered earlier. The possibility of the existence of a ball lightning with a composite core was also discussed in this model.
=== Hydrodynamic vortex ring antisymmetry === One theory that may account for the wide spectrum of observational evidence is the idea of combustion inside the low-velocity region of spherical vortex breakdown of a natural vortex (e.g., the 'Hill's spherical vortex').
=== Nanobattery hypothesis === Oleg Meshcheryakov suggests that ball lightning is made of composite nano or submicrometer particles—each particle constituting a battery. A surface discharge shorts these batteries, causing a current that forms the ball. His model is described as an aerosol model that explains all the observable properties and processes of ball lightning.