I think these are just electrical infrastructure shorting out. It's pretty obvious for the ones that occur at ground level on the horizon. The cloud lighting up blue is something obscured at ground level but reflected by the clouds.
Similar effect as "power flashes" from tornadoes; tornado blows on power lines, power lines short out, blue arc is produced, everything is bright blue for miles for a bit.
Similar effect as "power flashes" from tornadoes; tornado blows on power lines, power lines short out, blue arc is produced, everything is bright blue for miles for a bit.