The Physics of Lightning...

"Now, if you can separate these ions from one another, you create a separation of charge, which creates a Voltage. When the Voltage (also known as the electric potential difference) between two regions becomes too great -- even if air is the only thing between them -- it will spontaneously become conductive, and the rapid exchange of charge is what you see as a lightning strike!" Science Blogs

I admit: as a child, lightning frightened me. I still give it deep respect (and, I'm too big to dive under the bed anymore). So, if it's safe, I tend to do what my father did: look at it.

This simple exchange of sodium and chloride ions (i.e. salt: see Science Blog link), is all that the phenomena is:

100,000,000,000,000,000,000 = 10²⁰ electrons are exchanged in a single bolt:

I suppose: a dive for the bed would have warranted if I'd seen this display (if he physically could have, maybe Pop would have joined me):



 Eyjafjallajökull eruption


Science Blogs "Starts With a Bang": The Amazing Phenomenon of Volcanic Lightning!