Lightning

Lightning is one of the most beautiful displays we can see in our nature which can certainly be deadly at times. It is a sudden electrostatic discharge between the electrically charged regions of the cloud. As we know that it occurs due to electrically charged storms but still the method of charging of clouds remains elusive.

In the ancient times when amber was rubbed with fur, it attracted the light weighted objects such as hair. If we change our cloth in the dark we will see or hear some kind of spark. In 1752, one of the American scientists Benjamin Franklin said that the phenomenon of sparks from the clothes and lightning is same but people did not agree with him and it took 100 years to realise the truth.

We have seen electric sparks at many places for example sometimes we see electric sparks in electric poles when the wires become loose. We also see sparks in the plug if the connections in the socket are loose. In ancient times people did not understand the cause of lightning and they thought that it is some kind of wrath of gods which is visiting them.

What Causes Lightning?

Lightning can be explained in terms of charges produced due to rubbing. As we studied, during a thunderstorm, the air currents move upwards and the water droplets move downwards. And this caused the separation of charge due to this vigorous motion.

As a result of this process, the positive charges collect near the upper edge and the negative charges accumulate near the lower edge of the cloud and also near the ground. As the charge gets accumulated, its magnitude becomes very large. Water droplets in the air act as a conductor of this charge.

These charges flow to meet, thus producing strikes of lightning and thunder. For this phenomenon to occur, a sufficiently high electric potential between two regions and a high resistance medium must be present.

Sometimes lightning may be seen before the thunder is heard and this is because the distance between the clouds and the surface is very long and the speed of light is much faster than the speed of sound and hence lightning can be seen before the thunder is heard. You must know that the lightning frequency is around 40-50 times a second on Earth.

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Practise This Question

During lightning, which of the following occurs?