but how can a cloud posses a positive or a negative charge , and you said in the answer that the cloud rub over the water drops present in the cloud how can it be possible.

Asked by ayush.mathur | 23rd Jun, 2015, 09:11: PM

Expert Answer:

Clouds are itself condensed water vapours floating in the atmosphere. When cloude develops in the sky, winds moves upwards through the cloud and make the water drops present in the cloud to rub against one another. 
 
Refer the given figure'
 
Clouds carries electric charge. If cloud having negative charges at its bottom passes over a tall building or to the ground, it induces positive charges say, on the roof of the building. When the electric charges on the bottom of the cloud become extremely large, then thses tremendous electric charges present at the bottom of the charged cloud suddenly flow to the roof of the building or to the ground and we see a flash of lightingcoming towards the building. lighting strikes the earth or its tall structures when electric charges flow between the cloud and the earth through a tall building, 

Answered by Priyanka Kumbhar | 24th Jun, 2015, 12:06: PM

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