Question

Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?

Answer 1

Thunder and lightning occur simultaneously. It is known that the speed of light in air is [$3\times10^8m/s$], while the speed of sound in air is [$330\ m/s$].

Because the speed of light is significantly greater than the speed of sound, the flash is observed well before the sound of thunder during a lightning event.