at a time when it is cloudy .there may be  frequent thunder and lighting .the sound of thunder take some time to reach you after you see the lighiting.

can you answer why this happen.measure  this time interval using the digital  wrist watch and stop watch.calucalate the distance of lighting nearing point, speed of sound in air is 346m/sec

Light travels faster than sound. So, sound of thunder take more time to reach us and hence we hear the sound of thunder after we see the lightning.

Suppose, you see a lightning ‘t’ time before you hear the roaring sound of thunder and ‘S’ be the distance between you and the near point of the lightning. Since, velocity of light (299792458 m/s) is very large compared to the speed of sound. We can neglect the time interval between the lightning and the instant we see. So, the distance the sound had to travel with speed 346 m/s in time ‘t’ s to reach you is,

S = 346t m