Lightning

By Steffy Lo

Lightning

Lightning is an enormous electrical discharge, created when there is an unbalanced electrical charges in the atmosphere. It travels at a speed of 299 792 458 m/s, striking to the earth approximately 5-6km above ground. Lightning strikes often travels in 3 types of direction, from cloud to air, cloud to cloud, or cloud to ground. The strike results in the accompaniment of a loud sound called thunder.

Why do Lightning Strikes occur?

Lightning strikes occur when there is a charge separation between the clouds. This mechanism, also called the polarization of a cloud, allows the top part of the cloud to be positively charged and the bottom part to be negatively charged.

The cause of this is still unknown, but scientists came out with many different theories that explains how the polarization of a cloud takes place.

One theory involves the concept of charging through contact. According to the theory, charges are induced when ice crystals present in the clouds rebound off graupel. Graupel are soft ice-water mixture also known as snow pellets, formed when warm air turns into water droplets and collide with ice crystals.

The collision between the ice crystals and graupel resulted in the transfer of electrons from the ice crystals to the graupel, and this eventually leads to the induced charge separation between the clouds.

When the bottom of the cloud has accumulated enough negative charges that will attract the positive charges on the ground, it causes the electrons from the cloud to move towards the ground. As the positive ions surge upward and completes a path from the cloud to the ground, a lightning strike will occur.

The rapid flow of electric current releases a large amount of heat into the surrounding air, causing it to expand violently. This sudden and vigorous expansion of air creates a shockwave that can be heard as thunder.

Cloud Charging Model

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Lightning Rods

Lightning rods are originally invented by Benjamin Franklin and the purpose of it is to prevent lightning destructions in the society.

The concept of it is simple. Lightning rods are made of metal (for conductivity of electric currents) and usually attached at the top of the building, where lightning can flow easily. It connects to a copper or aluminum wire, which in leads the electric current to the ground, neutralizing it. The lightning rod ensures the safety of the community and reduces the likelihood of a lightning strike.

How Lightning Works?

How Lightning Works

Lightning Facts

  • Approximately 24,000 people die from lightning strikes yearly
  • A single thunderstorm can release 125 million gallons of water
  • A single lightning bolt carries about 5 billion joules
  • One storm can discharge enough energy to supply the entire world with electricity for about a minute
  • There are approximately 2,000 thunderstorms at any given moment worldwide
  • Besides creating an audible shock wave called thunder, lightning emits high energy radiation (X-rays and Gamma rays)