A Hypothesis Concerning Lightning Phenomena and Transmission-Line Flashover

1. There are differences among the lightning current data obtained by various investigators. These differences appear to be a function of the height and the terminating ground impedance of the structure on which the measurements were made. 2. There is agreement among the data obtained by magnetic links when the results were obtained from direct readings on tower or diverter rods or by the summation of readings made at each end of the ground wire of a stricken span. 3. Comparison of data obtained at sea level or at a high altitude (14,000 feet) based on measurements made of strokes to tower rods or ground wires as in conclusion 2, show no appreciable difference due to altitude. This appears to be contrary to the previously drawn conclusion based on a comparison of the high-altitude diverterrod data to sea-level lightning-current data based on the summation of tower currents. 4. There is disagreement among the lightning current magnitudes obtained as in conclusion 2 and those obtained by the summation of tower currents. 5. Lightning stroke data measured at the ESB are in disagreement with those obtained as in conclusion 2 by a factor of about two to one, particularly at the higher currents. 6. Examination of oscillograms obtained at the ESB show variations in the current wave shape that may be attributed to reflections occurring from the base of the building and other reflection zones around Manhattan Island. Thus, there are indications that the lightning stroke is not a constant current source.