Pitri Bhakta Adhikari
Tribhuvan University, Nepal
Title: Different types of lightning electric field waveforms observed in Kathmandu, Nepal
Biography
Biography: Pitri Bhakta Adhikari
Abstract
Lightning vertical electrical fields pertinent to the subtropical thunderstorms occurring over the rugged terrain were measured and recorded. More than six thousand three hundred flashes within the period of March, 2015 to June, 2017 have been recorded from the measuring station, Kathmandu, Nepal. Different types of lightning have been observed and analyzed among them the cloud-to-ground discharges are 21% and cloud-to-cloud are 34% whereas the unusual events are only 28% and remaining other events are 17%. The fine structures of the electric field signature have been analyzed for the first time in Nepal. Different types of lightning occur due to the lower positive charge region of the tri-pole structure of the cloud and positive lightning occur due to mountainous hilly region. Some unusual lightning events besides the positive lightning and cloud flashes have been observed on multiple thunderstorm days, which were analyzed assuming them to be positive ground flashes. The opposite polarity pulse occurred just prior to the main waveform. The average amplitudes of the opposite-polarity pulses with respect to those of the following main waveform were found to be 38%. The average durations of the main waveform and the
preceding opposite-polarity pulse were 521 μs and 39.7 μs. The vertical electric fields were sensed by a parallel flat plate antenna kept on the top of a building at a height of about twelve meters. Such electric fields have been digitized and stored with the help of Pico scope 6404D and were analysed with the software provided.