A memory that came back from last year, I was on an overnight flight from Paris to Singapore. Coming across the water east of India (which apparently is one of the most storm prone areas there is) we were flying into storms. They weren't that rough, but as we flew towards the storm cells there were a few flashes of lightning up ahead but not too much.
Once we flew into the clouds the lightning was almost continuous. Even though bolts weren't visible the sky kept lighting up. The atmosphere was obviously highly charged as I could see sparks forming on the wings of the 747, staying there for a few seconds before disappearing.
So I guess the turbulence caused by the plane flight must have triggered at least small lightning discharges in the clouds around us?
