Lightning Strikes Linked to Climate Change

In News

Recently, India’s second annual report on lightning was released by the Lightning Resilient India Campaign (LRIC).  

About

• Study pointed out that Lightning strikes are linked to climate change as 1,697 killed in a year in India.
• Lightning strikes increased 34% compared to previous year in India
• Monitoring of lightning for climate science and services was limited. 
• Hence, lightning was added to the Global Climate Observing System’s list of Essential Climate Variables in 2016

Global

• Brazil: The rise in incidence and intensity of lightning strikes in Brazil could be due to global warming and the growth of major urban centers, 
• Relation to temperature rise: An increase of one degree Celsius would increase the frequency of lightning strikes by 12 per cent
• Arctic Region: Links were established between climate change and rising incidences of lightning in the Arctic region.
  • Though this link has not been proven fully.
• Increasing trend: The number of lightning strikes recorded during the summer months between 2010 and 2020 shot up from around 18,000 at the start of the decade to more than 150,000 by 2020
• In May 2021, researchers in Australia linked excess CCN to the increased number of lightning strikes during the 2019-20 Australia forest fires.

India Specific

• Increased lightning strikes: 
  • 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. 
• More risk: 
  • Coastal areas may be at the highest risk.
• Cloud burst events: 
  • Party to research by India: 
    • Scientists from the Hemvati Nandan Bahuguna Garhwal University, Srinagar, and the Indian Institute of Technology, Kanpur, 
    • Established a link between cloud burst events, which cause sudden heavy rainfall often triggering flash floods, and forest fires.
  • Study on Cloud Condensation Nuclei : 
    • CCN are tiny droplets or cloud seeds on which water vapour condenses
    • For three years, the scientists have studied the concentration of cloud condensation nuclei in different weather conditions in the Central Himalayan region 
    • They  have found that there is a five times higher concentration of CCN in the atmosphere during forest fires as against during rains.

Lightening and its Strike Procedure

• Definition:
  • Lightning 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. 
  • 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.
• Procedure: 
  • 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.
• Collision: 
  • 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. 
• Electrical difference between two layers: 
  • 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.
• Enormous heat release: 
  • 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.
• Reaches Earth:
  • 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.
• Lightning strikes more on: 
  • There is a greater probability of lightning striking tall objects such 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.

Way Ahead

• States should undertake lightning micro-zonation for the regions depending on their geography to handle the disaster and death risks better.
• Better and state of the art Early Warning Systems.

Sources: DTE