Lightening phenomenon

Subject: Science and tech

Context:

In UP, five people were killed and one injured after being struck by lightning in the state.

Concept:

Lightning is an electrostatic discharge that releases tremendous amount of energy, with the rapid movement of electrons converting air to super heated plasma.
There are three categories of lightning
intracloud (IC), which is flashes within a cloud
cloud to cloud (CC), where lightning jumps from one cloud to another
cloud to ground (CG), where lightning strikes from the ground.

Mechanism

A fast, upward movement of air during a thunderstorm, called an updraft, carries with it warm humid air.
As it 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.
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.
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.

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.
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.
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.

The world’s most electric place

The most lightning activity on Earth is seen on the shore of Lake Maracaibo in Venezuela
At the place where the Catatumbo river falls into Lake Maracaibo, an average 260 storm days occur every year, and October sees 28 lightning flashes every minute — a phenomenon referred to as the Beacon of Maracaibo or the Everlasting Storm.