Editing Ball lightning (section)

=== 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.<ref>{{cite journal |author-link1=Pyotr Kapitsa|last1=Капица |first1=П. Л. |year= 1955|script-title=ru:О природе шаровой молнии|journal=Докл. Акад. наук СССР |volume=101 |page=245 |language=ru |trans-title=On the nature of ball lightning}}</ref><ref>{{cite encyclopedia |last1=Kapitsa |first1=Peter L.|author-link1=Pyotr Kapitsa|editor=Donald J. Ritchie |encyclopedia=Ball Lightning: A Collection of Soviet Research in English Translation |title=The Nature of Ball Lightning |edition=1961 |year=1955 |publisher=Consultants Bureau, New York |oclc= 717403|pages=11–16 |isbn=9780835759502}}</ref>

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.<ref>{{cite journal |last1=Handel |first1=Peter H. |author2=Jean-François Leitner |year=1994 |title=Development of the maser-caviton ball lightning theory |journal=J. Geophys. Res. |volume=99 |issue=D5 |page=10689 |url=http://europa.agu.org/?view=article&uri=/journals/jd/93JD01021.xml |archive-url=https://archive.today/20120713173033/http://europa.agu.org/?view=article&uri=/journals/jd/93JD01021.xml |url-status=dead |archive-date=13 July 2012 |bibcode=1994JGR....9910689H |doi=10.1029/93JD01021 |url-access=subscription }}</ref>

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.
<ref>{{cite journal | last=Wu  | first=H. C. | title = Relativistic-microwave theory of ball lightning  | journal = Scientific Reports  | volume = 6  | pages=28263 | date = June 2019  | doi=10.1038/srep28263 | pmid=27328835 | pmc=4916449 | arxiv=1411.4784 | bibcode=2016NatSR...628263W }}</ref> 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.