Copyright 2004, all rights reserved

John Abrahamson's ball lightning theory

John Abrahamson, a chemical engineer and associate professor at the University of Canterbury in Christchurch, New Zealand postulates burning aerosol as the cause of ball lightning.  He theorizes that when ordinary lightning hits soil, it vaporizes silicon dioxide and carbon, both common in soil. The lightning energy changes the state of these silicon compounds to pure silicon by removing oxygen (via combining oxygen with the carbon compounds). The resulting silicon vapor condenses into tiny nanospheres, each of which has a diameter of about 100 atoms. The nanospheres collect into long strings.

The lightning bolt digs a hole in the ground as it makes the vapor and forms a hot channel to the atmosphere for the vapor. The piping-hot vapor erupts into the air as a puffed jet and forms a spinning "smoke" ring made of condensing silicon vapor. The ring morphs into a glowing ball that remains glowing hot as the silicon nanospheres combine with oxygen in the air and burn — akin to dandelion down set afire. Once in this robust spherical shape, the ball continues to burn, stays hot and visible, and can move long distances.

A rising incandescent vortex ["smoke" ring] from a simulated lightning strike onto soil, see John Abrahamson, Phil. Trans. R.Soc. Lond. A (2002) 360, 61-88.  [John Abrahamson, used with permission]

A layer of oxide on the surface of each nanospheres slows the process. Eventually the particles run out of combustible silicon.  Then the ball either fades away or — if the temperature has risen to the melting temperature of the nanospheres — the tiny layers break and the ball explodes.

Abrahamson and his colleagues are trying to produce a lightning ball in the lab. So far, they have only managed the precursor to balls of fire — short-lived glowing "smoke" rings.