Natural Phenomena

 

Rain, thunder and lightening

Clouds carry an electric charge

The precursor of any lightning strike is the polarization of positive and negative charges within a storm cloud. The tops of the storm clouds are known to acquire an excess of positive charge and the bottoms of the storm clouds acquire an excess of negative charge.

All these collisions cause a buildup of electrical charge. ... Heavier, negatively charged particles sink to the bottom of the cloud. When the positive and negative charges grow large enough, a giant spark - lightning - occurs between the two charges within the cloud.

Lightning

Lightning is observed as a bright streak of light during a thunderstorm. Lightning is always accompanied by the sound of thunder. The transfer of charge from clouds to the earth or from cloud to cloud is called lightning. In simple words; lightning is an electric spark which happens on a grand scale in the sky.

Mechanism of Lightning

  • During a thunderstorm, the air currents move upward and water droplets move downward. These movements take at very fast pace and it results in separation of charges in the clouds.
  • The positive charges accumulate at the upper edges of the clouds and the negative charges accumulate at the lower edges of the clouds. Scientists are yet to understand the exact reason for this.
  • At the same time, the ground becomes positively charged.

Air is a bad conductor of electricity under normal circumstances. But when the amount of charge becomes too much in the clouds, the air is not in a position to hold on to this charge. As a result, the electric charge is transferred to the ground. This appears like a bright streak of light across the sky; which lasts for a few seconds.

Dangers of Lightning

Lightning can damage houses and trees. It can also kill people and cattle. Sometimes, lightning can main a person for life.

Safety during Lightning

  • No open place is safe during lightning and hence a home or any other building is the safest place during lightning.
  • The first sound of thunder is like a warning call for lightning. Hence, one should rush to a building soon after hearing a sound of thunder. One should come out of home only a few minutes after the last sound of thunder.
  • You should not carry an umbrella (with a metallic handle) during a thunderstorm. The metallic handle can be a potential target for lightning.
  • Tall trees and other tall structures are more prone to be hit by lightning. If you are caught in the open, try to hide under a short tree.
  • If you are in open and have no place to hide, then crouch on the ground and keep your head between your knees and hands.
  • Don’t take shower during lightning.
  • Use of phone should be avoided during lightning.
  • Television should be disconnected from the antenna.
  • Avoid operating the electric switches during lightning.

Lightning Conductor

This is a simple device which protects a building from being hit by lightning. It is composed of a vertical metal rod which usually has a trident at the top. The base of the metallic rod is attached to the thick metallic wire; which goes very deep inside the earth. This metallic wire provides a passage for earthing.

When lightning strikes, the electric charge goes to the lightning conductor and it then goes to earth. Thus, a lightning conductor helps in preventing any damage to the building.