What are lightning and thunder?

          Rain is often accompanied with thunder and lightning. Even though lightning and thunder are simultaneously produced in the clouds, the flash of lightning reaches us much before the sound. This is because light travels much faster than sound.

          Although lighting seldom reaches the Earth, there have been instances of death by lightning. When it flashes, a bright streak is drawn in the clouds. In reality, this streak is there either between two clouds or between the clouds and the Earth. Whenever a charged cloud approaches the Earth’s surface, opposite charge is produced in it. When the potential difference between the two is much higher than the resistance of the air, electricity flows through the air towards the Earth. As a result, lightning flashes. Similarly, when two charged clouds approach each other, there is a flash of lightning. This flash can be as long as 50 km.

           The lightning produced between the Earth and the clouds, is dangerous for high buildings. In order to protect these buildings from lightning, pointed metallic rods are fixed at the roof-tops of these buildings and these rods are taken through the walls down to the Earth and buried in it. They are called lightning conductors. Buildings fitted with these conductors cannot be damaged by lightning.

          Scientists are of the view that once you have seen the flash, you are completely safe from the ill-effects of the lightning. Thus, when lightning flashes, one should not get frightened and rush indoors, but come out in the open.