Once as a teenage (somewhere in the early 90s) I was watching a thunderstorm in suburban Sydney. I saw lightning strike (probably 5-10km) away, then a couple of

Once as a teenage (somewhere in the early 90s) I was watching a thunderstorm in suburban Sydney. I saw lightning strike (probably 5-10km) away, then a couple of seconds after the strike from about where the lightning hit, a blue 'bubble' (though with diffuse edges) rose (as though inflating) then fell/deflated over the course of a few seconds. I've never gotten a good explanation for what it was, though this picture makes me think lightning struck an electricity sub station, caused a brief electrical fire which lit up the sky as it got more intense, then died off.