Lightning Interactions with Humans and Lifelines

ABSTRACT

Lightning is one of the fascinating phenomena exhibiting tremendous natural power. It is source of awe, curiosity, enticement, inspiration as well as fear. On average, 50 lightning strikes occur on earth in one second. Fortunately not all of them kill people, albeit 10% people fall prey to lightning annually, out of which hardly 20 to 25% die. Lightning injures victims by heat, shockwave, intense brightness, radio waves, and secondary slip or fall mechanisms. Lightning injury is different from the normal electric shock as it involves transient flashover unlike the electrical contact freeze, wherein alternating (AC) and direct currents (DC) pass through the conductive interior body. Vacuity in knowledge is the driving force behind discoveries and inventions. Lightning experts had hardly developed any concurrence on lightning physics, and the observation of dark lightning complicated the Gordian knot. Lightning preventive, alerting and control devices help reduce fatality rates by the bolts out of blue skies. Lightning was considered to be the second cause of death making natural disasters after flashfloods but preventive measures have slithered it down to the third place in developed countries. Lightning prevention rule recommends ‘when the thunder roars, go indoors’. This work describes lightning characteristics, damage thresholds to humans, machines, energy infrastructures, airplanes, wind turbines, light railway tractions, underground cables and pipelines. Power and energy lifelines such as transmission lines, oil tankers and gas or petroleum pipelines are susceptible to lightning strikes. Artificial rocket and laser triggered lightning protection and control techniques help to divert the lightning attacks. Interaction of lightning with power and energy infrastructures disrupts these lifelines. However, lightning itself is viewed as an extraterrestrial energy source. Lightning energy harvesting is an interesting application which has been investigated quantitatively.

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