Lightning


 
 
Concept Explanation
 

Lightning

Lightning: lightning occurs because of a massive electric charge flowing from cloud to cloud, from one part of the cloud to another, or from a cloud to the ground. Thunder clouds carry electric charges, and these charges separate out within the cloud. The lower portion of a cloud generally carries negative charges and the upper portions carry positive charges. These charges keep building up. Normally, charges do not flow easily through air. Air is an insulator, but when a huge amount of charges builds up, the insulating property of air breaks down. The path of conductive air (due to charged particles) which extends from the thundercloud is made by what is called a step leader. The step leader is not as bright as the flash of lightning. A very large amount of electric current is generated during a lightning strike. The air in the path of lightning heats up enormously. The enormous amount of heat produced makes the air expand very suddenly. This causes a wave of vibrations (called a shock wave), which is the cause of the thunder.

Uses of lightning: Lightning which was feared at one time is now useful in many ways. The uses of lightning are:

  • High discharge of electric charge through air helps in fixing nitrogen. Nitrogen from the air combines with the oxygen forming nitric oxide and nitrogen dioxide gases. Nitrogen dioxide gas gets dissolved in rain water forming dilute nitric acid. Nitric acid comes to the soil with the rain where it reacts with calcium and other elements forming their nitrates. The nitrates are excellent fertilizers which helps palnt growth.
  • Ozone is formed when electric charge passes through the oxygen in the air. Lighting is most effective in the formation of ozone in nature. Ozone, as we know, forms a thin layer in the upper atmosphere. This layer is protective for the life on earth. Ozone screens out harmful ultraviolet rays coming from the sun.
  • It is belived that lightning played an important role in the origin and evolution of life on earth.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Lightning always follows ________________

    Right Option : A
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    Explanation
    Question : 2

    The lower portion of a cloud generally carries __________________

    Right Option : D
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    Explanation
    Question : 3

    The upper portions of cloud carry _______________-

    Right Option : B
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    Explanation
     
     


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