Effects of 200 km propagation on Florida lightning return stroke electric fields

The electric fields produced by lightning return strokes near Kennedy Space Center, Florida, have been measured simultaneously at distances of about 5 to 25 km and about 200 km. Detailed records of the first 12 microsec of waveforms from four strokes are presented, as well as data on the initial field risetimes for 58 first and 92 subsequent strokes. The mean field risetime measured between the 10 to 90% points was about 1 microsec at the close station and about 2 microsec at the distant one.