It has been mistaken for UFOs, wreaked havoc on homes and eluded rational explanation for centuries.
But now ball lightning, a large, mysterious glow that appears during thunderstorms, has been explained by scientists for the first time.
The eerie orb-light glow is created when microwave radiation given off during a lightning strike becomes trapped inside a plasma bubble, new research suggests.
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The eerie orb-like glow created by ball lightning (pictured) has finally been explained by scientists
Researchers from Zhejiang University in Hangzhou, China, have proposed that the bright glow of lightning balls is created when microwaves become trapped inside a plasma bubble.
'At the tip of a lightning stroke reaching the ground, a relativistic electron bunch can be produced, which in turn excites intense microwave radiation,' the scientists said in a research paper published in Scientific Reports.
'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 continue to generate plasma for a moments to maintain the bright flashes seen during ball lightning, they added.
The fireball eventually fades away as the radiation held within the bubble starts to dissipate - and when microwaves leak out, the lightning balls can dramatically explode.
Ball lightning, also known as fireballs and ghost lights, have spooked sky-watchers for hundreds of years.
The strange phenomenon can appear in the sky from the size of a golf ball to several metres across and can last between one second and tens of seconds.
The orbs mostly appear during thunderstorms, but can also form inside aircraft and closed rooms.
And the globe-like structures can decay silently or explode loudly, producing rancid odours in their wake.
These strange and varying characteristics have presented a 'riddle' to scientists trying to work out their origins.
But now researchers have come up with a theory to explain how the mysterious fireballs form.