“Recent events have drawn attention back to a natural hazard that often goes unheeded: lightning. In several incidents across the country, around thirty individuals lost their lives due to lightning strikes. This brings to the forefront the fact that lightning is the chief culprit amongst accidental fatalities resulting from natural causes.
Understanding Lightning
Lightning arises from an extremely rapid, colossal discharge of electricity within the Earth’s atmosphere. It transpires as a natural electrical discharge of short duration and high voltage between a cloud and the Earth’s surface or within the cloud itself. This discharge is accompanied by a bright flash, sound, and occasionally thunderstorms.
Two primary types of lightning exist: inter-cloud or intra-cloud (IC) lightning, which are visible yet harmless; and cloud to ground (CG) lightning, dangerous due to high electric voltage and current resulting in potential electrocution.
Formation of Lightning
The differential in electrical charge between the top and bottom layers of a cloud leads to the creation of lightning. Typical lightning-producing clouds rise 10-12 km high, with their base hovering about 1-2 km above the Earth’s surface. As the water vapour in these clouds ascends, it condenses into water due to dropping temperatures at the top (-35°C to -45°C). This condensation creates immense heat, propelling the water molecules further up to below-zero temperature zones where they transform into small ice crystals.
A system emerges where smaller ice crystals ascend while larger ones descend. The resulting collisions cause the release of electrons, triggering a chain reaction that charges the top and middle layers of the cloud positively and negatively respectively. This sets off a massive current, heating up the air column between the cloud layers and causing them to appear red during a lightning event.
Ground Strikes and Damage
Though electrically neutral, Earth’s surface is relatively positively charged compared to the cloud’s middle layer and therefore attracts around 20-25% of lightning’s current flow. This induced current is responsible for damage to life and property on Earth’s surface. It is more likely that elevated objects like trees or buildings are struck by lightning.
To safeguard structures, a device called lightning conductor is utilized. It consists of a metallic rod, taller than the building, placed in the building’s walls during its construction phase.
Lightning Hotspots
The highest frequency of lightning activity globally is reported at Lake Maracaibo’s shore in Venezuela. Here, where the Catatumbo river merges with Lake Maracaibo, an average of 260 stormy days occur each year.
Climate Change and Its Impact on Lightning
Research warns of a potential increase in the frequency of lightning strikes by 12% for each degree Celsius of temperature rise. A study published in Geophysical Research Letters in March 2021 establishes a connection between the changing climate and the escalating instances of lightning in the Arctic region. The Indian Institute of Tropical Management (IITM) asserts that the global warming-induced climate crisis and consequent increase in moisture over land could be directly contributing to increased lightning incidents.
Increasing Lightning Strikes in India
As per the second annual report on lightning by Lightning Resilient India Campaign (LRIC), India witnessed approximately 18.5 million lightning strikes from April 2020 to March 2021. LRIC, an initiative collaborated on by several organizations including the National Disaster Management Authority, aims to reduce lightning-induced deaths to less than 1,200 per year by 2022. This count reflects a 34% surge in lightning strikes as compared to the previous year.”
