What is ball lightning?
In plain words
People have long reported glowing balls the size of a grapefruit that float for seconds after lightning strikes. No one has explained what stores the energy or made a convincing copy in the lab.
Precise statement
Ball lightning appears as luminous spheres about 10 to 50 cm across lasting about 1 to 10 s, often after cloud-to-ground strikes; a natural spectrum recorded in 2012 and published in 2014 showed soil elements such as Si, Fe and Ca. Identify the energy storage and emission mechanism (oxidizing silicon nanoparticle networks, plasma structures, microwave cavities, others). An answer is a laboratory reproduction matching size, lifetime, luminosity, motion and spectra of natural events.
What would settle it
A laboratory object reproducing natural size, lifetime and spectra, or additional instrumented natural observations that exclude candidate mechanisms.
Related problems
- More general than Does oxidizing silicon vapor from struck soil explain ball lightning?