Analysis of lightning current propagation on earth surface

Abstract

Weather experts report that lightning strikes the earth 100 times each second around the world and about 16 million thunderstorms occur worldwide each year. Lightning packs a punch equal to 100 million volts of electricity, a force powerful enough to tear through roofs and explode walls and chimneys. A lightning strike can generate temperatures as high as 90,000 degrees Fahrenheit (three times hotter than the surface of the sun) and can easily ignite fires. In addition to causing property destruction, direct lightning strikes kill nearly 40 people each year in Sri Lanka. Damages due to indirect effect of lightning is common in Sri Lanka, specially people claim that frequency of lightning damages have been increased after introducing communication towers in the country. This can be seen mostly in lightning prone areas. It is observed that after striking the ground, rather than going into the earth, these discharges propagate outward from the strike points on the earth surface. Propagation of lightning current on the earth surface occurs in a dendritic pattern, which is the main cause for many damages in the vicinity of communication towers. This paper will discuss various analysis of lightning current propagation on the earth surface in different soil types in Sri Lanka. Impact of different soil types for lightning current propagation also being discussed and mathematically analyze. This can be used as a base line to determine the placement of communication towers in order to minimize damages due to secondary effect of lightning and earth potential rise.