Simultaneously measured lightning return stroke channel‐base current and luminosity

The time delay between lightning return stroke current and the resultant luminosity was measured for 22 return strokes in eight lightning flashes triggered by the rocket‐and‐wire technique during the summer of 2014 in Florida. The current‐to‐luminosity delay measured at the channel base at the 20% amplitude level ranged from 30 to 200 ns with an average of 90 ns and at the 50% amplitude level ranged from 30 to 180 ns with an average of 94 ns. The delays are significantly shorter than that predicted by Liang et al. (2014) from theory. The current‐to‐luminosity delays increase with increasing current risetime, current risetime varying from 190 ns to 570 ns, but the delay appears not to depend on the peak current value.