Originally Posted by cmdahler
Regardless of how the charge is developed within the cloud, the discharge as lightning can only happen because of an initial charge separation (positive and negative charges accumulate in separate areas). Near the bottom of an ash cloud, a buildup of polarization will induce an opposite polarization on the surface just below it. If the charge builds up enough potential, then lightning between cloud to ground will result. I don't know if anyone has ever been struck by ash cloud lightning - probably not, likely because such lightning itself would be an exceedingly rare event (if that kind of lightning killed you, then you could definitely say it was just your time to go...). Lightning between an ash cloud and the ground probably doesn't happen very much just because ash clouds don't tend to hang at low altitudes over the ground - they are violently thrown high into the atmosphere almost immediately, and by the time they drift back toward the earth, the particles are so dispersed that the charge potential isn't nearly enough to cause a spark, let alone lightning. I've seen pictures of ash cloud lightning before, however, in which a bolt or two was clearly striking the ground. Not a place I'd want to be standing.
Here's one link. |