Theories
Its causes and its relation to common lightning are not known. Britannica Among the suggested explanations are air or gas behaving abnormally, high-density plasma phenomena, an air vortex containing luminous gases, and microwave radiation trapped within a plasma bubble. Britannica
They write that observations of ball lightning have been reported for centuries, but the origin of this phenomenon remains an enigma, and that several energy sources have been proposed, but none of those models has succeeded in explaining all of the observed characteristics. Nature 2000
The 2013 RMetS article calls the atmospheric maser theory the prevailing physical theory of ball lightning: electrical activity puts large clouds of charged water molecules into an excited state, briefly causing light amplification by stimulated emission of radiation. RMetS The same article says that before this can be confirmed as the cause, the process must be replicated in a laboratory. RMetS
The Met Office says there are various hypotheses, but the leading one is that the luminous sphere could be a bubble of glowing soil particles which was formed when the lightning strike hit the ground. Met Office
Their model is that when normal lightning strikes soil, chemical energy is stored in nanoparticles of Si, SiO or SiC, which are ejected into the air as a filamentary network, and as the particles are slowly oxidized in air the stored energy is released as heat and light. Nature 2000 They investigated this basic process by exposing soil samples to a lightning-like discharge, which produced chain aggregates of nanoparticles: these particles oxidize at a rate appropriate for explaining the lifetime of ball lightning. Nature 2000
Which idea is “leading”?
The 2013 Royal Meteorological Society article calls the atmospheric maser theory the prevailing physical theory, and says it would still need to be reproduced in a laboratory. A 2025 Met Office note says the leading hypothesis is that the luminous sphere could be a bubble of glowing soil particles formed when lightning hits the ground, which sits close to the silicon-nanoparticle model of Abrahamson and Dinniss (2000) and to the 2014 spectrum of Cen, Yuan and Xue, who found soil-element lines (silicon, iron and calcium) for the whole lifetime of one natural event. Those later papers also warn that there may be more than one type, and that one event may not represent all ball lightning. This site does not crown a single leading theory.
They also write that there may be more than one type of ball lightning and more than one mechanism that explains it, and that their observation is only one event that may not be representative of all ball lightning. PRL 2014
He quotes them further: “There may be more than one type of ball lightning and more than one mechanism by which ball lightning is generated”; “There have been many theories devised to explain ball lightning. None is completely satisfactory”; and “many luminous phenomena created in the laboratory are claimed by their creators to be ball lightning.” Keul 2021
He also said, “And likely it’s not one thing but several things that have similar observables.” RMetS
One 2012 event, with a spectrum of soil elements, is a strong piece of evidence for a soil-strike idea in that case. The authors themselves say it may not represent every report. We leave the theories on the table.