A series of laboratory experiments has demonstrated that high-voltage electrical discharges over water surfaces can produce luminous, ball-like plasma objects that share some characteristics with natural ball lightning. Researchers at the Humboldt University of Berlin and other institutions have created small plasma spheres by passing electrical arcs over water, which vaporizes and ionizes the liquid to produce short-lived luminous objects. These water-discharge plasmoids are typically small (1-5 centimeters), short-lived (fractions of a second), and confined to the immediate vicinity of the water surface. However, they exhibit several properties observed in natural ball lightning: a defined spherical boundary, luminosity independent of external energy input (at least briefly), and the ability to move laterally across the water surface.
The experiments suggest that water — or more broadly, any source of vaporizable material near a lightning strike — could play a role in natural ball lightning formation. This aligns with observations that ball lightning is frequently reported near bodies of water, in humid environments, and during rainstorms.