Thunder: A perennial threat

On my recent visit to my birth-village, I was shocked upon hearing the death of my village dweller, Madhab Bauri, due to lightning, followed by further deaths of three women who were engaged in sowing the paddy saplings in their agricultural field. Of course, they were just in the wrong place at the wrong time. That was a short-lived thunderstorm which hardly lasted 25 minutes. It was a very heavy sky, there was a flash and then the rumble. The villagers saw the lightning flash. This fatality was not only restricted to my village but also happened in other parts of India. Sadly, in my village, the people who died were from a poor family and were bound to work in the agricultural field to sustain their livelihood during the rainy season. Now, everyone remains in a panic to go outside during cloudy weather despite their poverty.

While discussing the issue related to fatality due to lightning, all senior citizens strongly advocate that this fatality has rapidly augmented over time since they never heard of so many deaths due to lightning in their childhood. The consolation for few people even today is that it happened due to sinful acts of victims. Their perception reminded me of Greek mythology – Zeus had dominion over the creation of lightning and humans can't prevent it. It is clear from the records that in India, thousands of deaths occur every year due to lightning. Such deaths are common in rural areas where most of the victims are mainly farmers or low waged labour.

Majority of deaths in rural areas is due to step voltage and touch voltage mechanism. Generally, in rural places, people are not aware of the danger of lightning. When there is a rain threat, people tend to take shelter under a nearby tree or inside a small hut or shed. People, who stand under the tree, are likely to lean on the tree and touch each other. And, when lightning strikes the tree, the person having contact with the tree will be affected by the touch voltage and if any other person has physical contact with the first person, he/she will also be affected. In the second case, casualty mostly occurs when people take shelter inside a hut, thatched roof, shed, etc. The houses are generally very small. People are likely to touch the side walls as well as each other. Some poor people who are working in farms are reluctant to stop work and take shelter when it rains. These people who are working in open fields are more prone to be affected by a step voltage. If there is a water body on the ground then the danger prone area is extended up to the end of the water body.

Convective activity is one of the most fundamental meteorological event that plays an important role in the atmospheric, energetic and hydrological cycle. Lightning is an electrical discharge that occurs within a thunderstorm. Its visual manifestation is a crack in the sky and it occurs when certain conditions are met. Particles in a cloud rub together, gathering opposite charges that eventually separate into positive and negative regions. These two poles create a space across which a transfer of charge—or lightning bolt—may then occur. Sometimes the bolts transmit the charge to the ground and lightning strikes. The amount of lightning generated is reported to be influenced by factors that go beyond natural meteorology, including aerosols. Recent studies have given credence to the idea – more intense lightning is connected with aerosol sources over land. Cloud droplets form when water vapour condenses onto aerosols. If there are lots of aerosols, there are more condensation sites, so the water is distributed among them to make smaller droplets. These little droplets are especially light and so it is easier for them to rise to higher levels of the cloud on thermal updrafts. They eventually freeze, partially forming what's known as graupel which tends to become negatively charged, and begin colliding with ice crystals (positively charged) also floating in the cloud – causing lightning.

Though the microphysics of charge separation and lightning generation due to increase of aerosol formation is still not fully understood, scientists have advocated where aerosol concentrations show an increasing trend – aerosols play a major role in the enhancement of lightning activity. Due to the increase in global temperature, meteorologists believe that lightning and thunderstorms will become more common; killing more people in the developing world. In this view, it is pertinent to mention that rapid industrialisation, urbanisation, conventional agriculture practice and advancement of energy-intensive technology without any concern to the environment mainly for the benefit of corporations, politicians and rich people with a little positive impact on society is responsible for aerosol formation and climate change. If the proposition of scientists about causes of lightning is true, a death penalty is imposed on the poor farmers working in open fields despite heavy rainfall or on quarry workers working in mineral deposits which are often on highlands and attract lightning.

Though lightning is the biggest killer, research on lightning and its aftermath have been sporadic in India. Further, this fatality gets less attention from the media and the government due to their isolated nature. Lightning generally causes less physical devastation compared to floods and cyclones and the impact caused is geographically scattered, sometimes only causing the death of two-three persons at a time. Therefore, requisite action or effort has not been taken to implement mitigation measures. Unfortunately, weather forecasting for thunderstorm and lightning is still not robust enough to generate an early warning in different parts of India.

There is an urgent need to improve early warning systems for preventing deaths from lightning. For this purpose, financial investment in science and technology is needed to communicate with the poor and vulnerable who take risks during cloudy weather to earn their livelihoods. The government in all states should consider introducing lightning arresters, lightning conductors and stronger infrastructure in rural areas. Public awareness of lightning safety is very poor. Emphasis must be given on educating the public, particularly in rural areas to prevent deaths from lightning. The central and state governments should take steps to conduct lightning awareness program extensively across the country. Currently, urgent need is that the UN, along with the national and state governments, makes concerted efforts to highlight the risk of this hazard and promote measures that the developing countries can afford to mitigate its effect.

(The author is a former Senior Scientist, Central Pollution Control Board. The views expressed are strictly personal)