Narrow positive bipolar radiation from lightning observed in Sri Lanka

Characteristics of narrow bipolar pulses observed in Malaysia

“…A measurement conducted in Sweden during June to August 2006, (Sharma et al, 2008) failed to record any narrow bipolar activities whereas the same experimental set up carried out in Sri Lanka, a tropical region, recorded numerous positive bipolar events. This indicates that NBPs are not common in temperate region compared to the tropical region.…”

“…Willet et al, 1989;Medelius et al, 1991;Sharma et al, 2008) or satellite based measuring system (Smith et al, 1999;Jacobson, 2003;Eack, 2004;Jacobson and Heavner, 2005;Weins et al, 2008). In most cases, they were reported as isolated events without being preceded or followed by another known lightning activity within a time frame of tens of milliseconds (Smith et al, 1999;Sharma et al, 2008). However, some studies found that NBPs were associated with the initiation of other intracloud discharges Jacobson, 2003;Jacobson and Heavner, 2005).…”

“…Meanwhile, Light and Jacobson (2002), reported that NNBPs occur at an altitude of 15-21 km while NPBPs occur at a lower altitude of 6-15 km. Hence it was speculated that strong updrafts (Suszycnsky and Heavner, 2003) and geographical conditions (Sharma et al, 2008) could play an important role in enhancing the occurrence of narrow bipolar pulses activity even though the exact mechanism of this event remains poorly understood.…”

Overview of Recent Progress in Lightning Research and Lightning Protection

“…Sharma et al [39] observed NBPs in Sri Lanka, but not in Sweden. Since cloud tops in Swedish thunderstorms (typically <10 km) are considerably lower than in Sri Lankan ones (typically >15 km), the observed difference in occurrence of NBPs in the two locations appears to be consistent with the tendency for NBP sources to be located at higher altitudes.…”

Features of Ground Flashes before and after the Massive Earthquake Observed from Kathmandu, Nepal

“…The signals so received were recorded by the pico-scope whose window size was varied from 200 -500 ms at different sampling rate of 40 -312 MS/seconds. A schematic diagram of the antenna and recording system that has been used in this study is adopted from Sharma et al (2008). …”