how can you tell?

gray clouds covering the sky..look

and there u go, a lightning bolt!

did you see the lightning bolt there ??

and now you are going to hear the sound of thunder!

may be not

most certainly

how can u say that so confidently?

because lighting and thundering happen at the same time

when clouds bang with each other in the sky

but we see lightning first because

light travels faster than sound

eerie!

see, I mean heard that? Hehehehe