Why in news?

A new study of lightning-related deaths in Bihar has revealed that various districts of Bihar were vulnerable to this natural hazard, recording the highest casualty rate per million population.

The study examined data from the 2017-2022 period and found that 1,624 people died and 286 were injured due to lightning.

What’s in today’s article?

• Lightning
• Areas which are lightning-prone
• Mitigating the effects of lightning strikes
• Reports on deaths caused by lightning in Bihar

What is lightning?

• About
  • Scientifically, lightning is a rapid and massive discharge of electricity in the atmosphere some of which is directed towards earth.
  • The discharges are generated in giant moisture-bearing clouds that are 10-12 km tall.
  • The base of these clouds typically lie within 1-2 km of the Earth’s surface, while the top is 12-13 km away. Temperatures in the top of these clouds are in the range of –35° to –45°C.
• Mechanism
  • Smaller ice crystals are moving up while bigger crystals are coming down
    • As water vapour moves upward in the cloud, the falling temperature causes it to condense.
    • As they move to temperatures below 0°C, 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.
  • Collision between these crystals and release of electrons
    • 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.
  • Potential difference between top layer and middle layer of the cloud
    • This collision 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.
  • Earth - a good conductor of electricity
    • 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.

Areas which are lightning-prone

• As per the report released by the Climate Resilient Observing Systems Promotion Council (CROPC) in 2022, following states are more vulnerable to lightning strikes:
  • Madhya Pradesh followed by Chhatisgarh, Maharashtra, Odisha and West Bengal.
  • Other states with high strike rate include Bihar, UP, Karnataka, Jharkhand and Tamil Nadu.
• Lightning is fairly common, though it is not often realised in the urban centres.
• In India, well over one crore lightning strikes have been recorded in recent years.
• It is only over the last few years that lightning records have begun to be maintained, due to the efforts of CROPC and India Meteorological Department.

Mitigating the effects of lightning strikes

• Lightning – not classified as a natural disaster in India
  • As of now, lightning is not classified as a natural disaster in India.
  • As per the Centre, deaths caused by it can be avoided through education and awareness.
• Setting up of an early warning system
  • India has set up of an early warning system, that is already saving many lives.
  • India is among the only five countries in the world with an early warning system for lightning and the forecast is available from five days to up to 3 hours.
• Most deaths happening in rural areas
  • More than 96% of lightning deaths happen in rural areas. As such, most of the mitigation and public awareness programmes need to focus on these communities.
  • Lightning protection devices are fairly unsophisticated and low-cost. Yet, their deployment in the rural areas, as of now, is extremely low.
• States are encouraged to prepare and implement lightning action plans
  • States are being encouraged to prepare and implement lightning action plans, on the lines of heat action plans.
  • An international centre for excellence on lightning research to boost detection and early warning systems is also in the process of being set up.

Reports on deaths caused by lightning in Bihar

• Annual casualty rate per million is highest in Bihar
  • Bihar’s annual casualty rate per million of 2.65 was higher than the national average of 2.55.
• Period between May to September was the peak for lightning strikes
  • The period between May to September was the peak for lightning strikes with June and July accounting for 58.8 per cent of lightning-linked deaths.
  • Researchers explained that lightning strikes reach a record high in June and July with the monsoonal current setting in, mainly due to the interplay of easterly and westerly winds.
• The plains area is prone to thunderstorms and lightning activity
  • The plains area is prone to thunderstorms and lightning activity as warm, dry air from north-west India converges with moist air emanating from the Bay of Bengal.
  • This creates conditions that are favourable for the formation of deep convective clouds.
• Higher population density and socio-economic factors also play a role
  • In North West Bihar, the lightning strikes are lower but casualties are higher.
  • These parts of Bihar are not urbanised and may be having poor shelter density around farm areas.
  • Socio-economic factors play an important role in mitigating the impact of such natural hazards.
• Threat potential of lightning strikes is not uniform
  • Topography, elevation, and local meteorological factors determine the spatial distribution of lightning strikes.
  • A higher lightning frequency is seen in the eastern region owing to higher moisture incursion.