CHARACTERISTICS OF LIGHTNING FLASHES OBSERVED IN SRI-LANKA IN THE TROPICS

Characteristics of lightning ground flashes in Sri Lanka, in the tropi cs, were measured by recording the electric field generated by the who le flash at microsecond resolution. The geometric and arithmetic means of the interstroke intervals were 57 ms and 83 ms, respectively. It w as found that about 35% of the multiple stroke, negative ground flashe s had at least one subsequent stroke with a peak electric field larger than that of the first return stroke. Furthermore, about 12% of the s ubsequent strokes had peak electric field amplitudes larger than those of the first return strokes. The geometric mean of the subsequent str oke peak field to the first return stroke peak field ratio was 0.44. T he mean number of strokes per flash was 4.5, and 21% of the flashes we re single-stroke flashes. A comparison of the results with those obser ved in Florida and in Sweden shows that there are remarkable similarit ies in the characteristics of lightning ground flashes observed in dif ferent geographical regions.