With the advancement of monsoon in India in July 2021, the instances of lightning was quite common and on July 12, 2021 nearly 68 life ended in a single day in Uttar Pradesh, Rajasthan & Madhya Pradesh.
What is lightning?
- Lightning is a very rapid and massive-discharge of electricity in the atmosphere, some of which is directed towards the earth’s surface.
How does it strike?
- Electrical discharges are generated in giant moisture-bearing clouds that are 10-12 km tall.
- The base of these clouds typically lies within 1-2 km of the Earth’s surface, while their top is 12-13 km away.
- Temperature 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 cyrstals are coming down.
- Collision 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 situation in which the top layer of the cloud gets positively charged, while the middle layer is negatively charged.
- An enormous amount of heat is produced and this leads to the heating of the air column between 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 results 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 of life and property on Earth.
Government Initiative to reduce death by Lightning
- DAMINI: Lightning Alert – launched in 2018. It gives the exact location of current lightning strikes and the probable location of impending strikes to users in an area of 40 sq. km, so they can take shelter.
- Since 2019, the ‘Lightning India Resilient Campaign’ launched and has set itself the task of reducing such deaths by 80% by 2021.
- We need to improve awareness about lightning.
- The communication reach needs to be improved.
- The early warning needs to be communicated in the local language.
- States should install the lightning arresters that can reduce fatalities.
@ Yogesh Pratap Singh