On 29/05/2016 15:48, Stephen Davenport wrote:
"It was reported by eye-witnesses, both from France and Germany, that the
lightning came from cloudless sky, what is that type of lightning called?"

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Clear-air lightning, I suppose, or popularly "a bolt from the blue". It's a positively charged strike that originates in the anvil of a cb and travels horizontally before turning towards the ground. Most cloud-to-ground lightning has negative charge.

Stephen.


As long as it was not in-air piezo-electric discharge, precursor to
earthquakes.