Lightning is a very rapid and massive discharge of electricity in the atmosphere. It is the process of occurrence of a natural ‘electrical discharge of very short duration and high voltage between a cloud and the ground or within a cloud.
- These discharges are generated in giant moisture-bearing clouds that are 10-12 km tall. These clouds have their bases about 1-2 km from the Earth’s surface.
- There are two types of lightning. Such as,
Intercloud or intracloud (IC) lightning: These are visible and harmless.
Cloud to ground (CG) lightning: This is harmful as the ‘high electric voltage discharge for very short time leads to electrocution.
- It is a result of the difference in electrical charge between two points.
- As water vapour moves upwards in the cloud, the falling temperature causes it to condense. A huge amount of heat is generated in the process, pushing the water molecules further up.
- As they move to temperatures below zero, droplets change into ice crystals. This leads to a system where smaller ice crystals move upwards while larger ones come down.
- The resulting collisions trigger the release of electrons. This process is similar to the generation of electric sparks. The moving free electrons cause more collisions and more electrons, leading to a chain reaction.
- Over time, this process results in a situation where the top layer of the cloud gets positively charged and the middle layer is negatively charged.
- The electrical potential difference between the two layers is huge (a billion to 10 billion volts). So, in a short time, a massive current (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. As the heated air column expands, it produces shock waves that result in thunder.
- 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 lightning.
Lightning strikes in INDIA:
- According to a report on lightning by Climate Resilient Observing Systems Promotion Council (CROPC), in 2019-20, about 1.4 crore lightning strikes were recorded which increased to 1.85 crores in 2020-21.
- Madhya Pradesh has reported the largest number of cloud to ground lightning strikes followed by Chhattisgarh, Maharashtra, Odisha and West Bengal.
Ways to reduce impact:
- Lightning needs to be listed as a notified disaster by the Ministry of Home to get required attention in national policy directives and developmental programmes.
- 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.
- Thirdly, lightning protection devices are fairly unsophisticated and low-cost. Yet, their deployment in the rural areas, as of now, is extremely low. Hence, they should be deployed.
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