The same storm .. or another has just arrived over my office in Dartford. The same effect is apparent, that the first sound appears 3 - 10 secs after the flash but the rumblings continue for up to 45 secs. Unless the lightning bolt is 10 miles long, (how long are they ??) I can but assume we are getting echos back from ground features.
If my recollection is correct : speed of sound = 760 mph = 760 miles in 3600 secs. So 1/760 x 3600 = 4.7 secs/ mile.
Or is it that the lightning starts a mile away, which I hear 5 seconds (ish) later but also the sound travels 5 miles and reflects back (from Thurrock Shopping centre or something) and between 5 seconds and 45 seconds I am also getting all the other noise from the middle and other end of the lightning flash plus all the other ground refections as well until they reduce in volume and I don't hear them.
Is there somthing in heavy rain bearing cloud that allows sound to reflect back and too inside them as well ?? because it is really pretty flat in these parts.
DGG
