Rain is often accompanied with thunder and lighting. Even though lightning and thunder are produced simultaneously in the clouds, we see the flash of lightning much before the sound is heard. This is because light travels much faster than sound. The speed of light is 300,000 kilometres per second, while sound travels 340 metres per second. Although lightning seldom reaches the Earth, there have been instances of death by lightning. When it flashes, a bright spark is drawn between 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 air, electricity flows through the air towards the Earth. As a result, lightning takes place. Similarly, when two charged clouds approach each other, there is a flash of lightning. The flash of a lightning can be as long as 50 kilometres. The lightning produced between the Earth and the clouds, is dangerous for high-rise buildings. In order to protect these buildings from lightning, pointed metallic rods are fixed on the rooftops of these buildings and these rods are connected to metal plates buried in the Earth. They are called lightning conductors. Lightning does not damage buildings fitted with these conductors. 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.