five second rule

31 July 2002

i learnt a rule of thumb as a child (no idea who from, probably an equally uninformed fellow child) that each second delay between the lightning and the thunder meant the storm was a mile away. i’d never questioned this until i was lying in bed this morning looking at the thunderstorm and doing maths in my head (it beat getting up, ok?). sound travels at 330 metres per second or thereabouts. so the sound of thunder will take three seconds to travel a kilometre. so there’s no way it can travel a mile in a second. it takes the sound of thunder five seconds to travel a mile.

that storm is closer than you think.