Survey on electrical activity in earth’s atmosphere

Abstract

Lightning discharge is a spectacular, luminous and one of the most dangerous short lived phenomenon which occurs in the Earth‟s atmosphere ranging from troposphere to the lower ionosphere. Lightning in troposphere is mainly classified as cloud-to-ground (CG) lightning, intra-cloud (IC) lightning and inter-cloud or cloud-to-cloud (CC) lightning discharges. It is assumed that these discharges are caused by the electrically charged thunderclouds. CG lightning has been studied more and is further categorized as positive CG and negative CG lightning. Positive CG lightning is more powerful and accounts only (5-10) percent of the total global lightning and may carry a peak current of >300 kA. An entire family of other electrical discharges also has been reported by the scientific community. They are called “Transient‟s Luminous Events (TLE‟s)”. TLEs occur from top of the thunderclouds up to the lower ionospheric altitudes. Their first visual evidence was documented in 1989. TLE‟s are included as blue starters, blue jets, gigantic jets, red sprites, halos, and elves. They are named according to their optical properties, terminal altitudes and different shapes. It has been observed that TLE‟s are associated with underlying thunderstorm activity and strong tropospheric lightning. The exact physical mechanism of lightning and TLE‟s and their association with the underlying thunderstorms is still unknown and the research is going on. In this paper, we will study the possible mechanisms of these electrical discharges, their inter-connection and impacts on the atmosphere. This paper is aimed at the readers generally are unfamiliar with the lightning characteristics. We hope that this article will increase the interest among the researchers.