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Introduction:
Lightning strikes have claimed more than 70 lives in the past 24 hours in Rajasthan, Uttar Pradesh and Madhya Pradesh. Just weeks ago, at least 27 people were killed in lightning strikes in several districts of West Bengal. Despite rapid advancement in technology, lightning strikes remain the most common reason for deaths by forces of nature. According to the last available statistics from the National Crime Records Bureau, there were 8,145 deaths in the country attributable to forces of nature in 2019. Of these, 35.3% deaths were reported due to ‘lightning’. While between April 2020 to March 2021, lightning strikes have killed 1,619 people, according to India’s second annual Lightning Report. The report also says that there has been a 34% rise in lightning strikes in the country. And just 5 states – Odisha, Madhya Pradesh, Chhattisgarh, West Bengal and Jharkhand – have witnessed the maximum lightning strikes.
Lightning strikes in India:
- Bihar is second after Uttar Pradesh with the maximum number of deaths due to lightning.
- At least 170 people died in Bihar due to lightning in 2019 between April 1 and July 31.
- The number of lightning days across India have been increasing significantly every month.
- Lightning strikes kill morepeople in India than any other extreme weather event.
- Climate change may be sparking more lightning across the world, and there is an increasing scientific evidence pointing to the trend.
- The rise in incidences and intenstity of lightning strikes in Brazil could be due to global warming and the growth of major urban centers.
- According to a journal, the frequency and intensity of lightning strikes in India are expected to increase by 10-25 per cent and 15-50 per cent by the end of this century. Coastal areas may be at the highest risk.
- An increase of one degree Celsius would increase the frequency of lightning strikes by 12 per cent, warned a study published 2015.
- An increase in lightning incidents can also be linked to the availability of more moisture over land due to warming, according to the Indian Institute of Tropical Meteorology, Pune. A 10-year study by three researchers at the institute, released in 2010, established a link between cyclonic storms that developed over the Bay of Bengal and weather disturbances over the Arabian Sea during the post-monsoon season. This, it seems, drives the lightning activity over the coastal and adjoining continental region of the peninsula.
How can deaths be minimised?
Every lightning strikes around a fixed period and almost similar geographical locations in similar patterns.
- As per CROPC (Climate Resilient Observing Systems Promotion Council), early lightning warning to farmers, cattle grazers, children and people in open areas is the key.
- Then a local lightning safety action plan, like installing Lightning Protection Devices, is also need to prevent deaths.
What is the impact of lightning?
The Centre had increased compensation for victims of natural disaster to Rs 4 lakh in 2015.
- In the last five years there were 13,994 fatalities, which bring the total compensation to around Rs 359 crore.
- There have been phenomenal losses of animal life also from lightning strike.
What is lightning?
- It is a very rapid — and massive — discharge of electricity in the atmosphere, some of which is directed towards the Earth’s surface.
- These discharges are generated in giant moisture-bearing clouds that are 10-12 km tall.
How does it strike?
- The base of these clouds typically lies within 1-2 km of the Earth’s surface, while their top is 12-13 km away. Temperatures towards the top of these clouds are in the range of minus 35 to minus 45 degrees Celsius.
- As water vapour moves upward in the cloud, the falling temperature causes it to condense.Heat is generated in the process, which pushes the molecules of water further up.
- As they move to temperatures below zero degrees celsius, the water droplets change into small ice crystals. They continue to move up, gathering mass — until they are so heavy that they start to fall to Earth.
- This leads to a system in which, simultaneously, smaller ice crystals are moving up and bigger crystals are coming down.
- Collisions follow, and trigger the release of electrons — a process that is very similar to the generation of sparks of electricity. As the moving free electrons cause more collisions and more electrons, a chain reaction ensues.
- This process results in a situation in which the top layer of the cloud gets positively charged, while the middle layer is negatively charged. The electrical potential difference between the two layers is huge — of the order of a billion to 10 billion volts. In very little time, a massive current, of the order of 100,000 to a million amperes, starts to flow between the layers.
- An enormous amount of heat is produced, and this leads to the heating of the air column between the two layers of the cloud. This heat gives the air column a reddish appearance during lightning. As the heated air column expands, it produces shock waves that result in thunder.
How does this current reach the Earth from the cloud?
- While the Earth is a good conductor of electricity,it is electrically neutral. However, in comparison to the middle layer of the cloud, it becomes positively charged. As a result, about 15%-20% of the current gets directed towards the Earth as well. It is this flow of current that results in damage to life and property on Earth.
- There is a greater probability of lightning striking tall objectssuch as trees, towers or buildings. Once it is about 80-100 m from the surface, lightning tends to change course towards these taller objects. This happens because air is a poor conductor of electricity, and electrons that are travelling through air seek both a better conductor and the shortest route to the relatively positively charged Earth’s surface.
Conclusion:
- While the impact climate change will have on our weather still remains uncertain, researchers agree that by implementing simple measures like lightning detection systems and installing grounding systems in buildings could go a long way in avoiding deaths and injuries.
- Thunderstorm patterns can’t be changed, but the protection is out there, with lightning detection systems acting as the only reliable and consistent way of issuing a lightning warning. Around 90% of thunderstorms are already producing lightning by the time they are within 12 miles (20 km), making a system an invaluable investment for a future of weather uncertainty.
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