In a message dated 06-08-15, mark lewis said to Holger Granholm:

Hi Mark,

ml> here we use a 4 second rule...

ml> 1. see lightening flash
ml> 2. start counting - 1onethousand, 2onethousand, 3onethousand, etc
ml> 3. stop counting when the thunder is heard
ml> 4. divide the count by four and that's how many miles away the
ml> strike was

ml> dunno how favorably that compares with sound and 3 seconds per
ml> kilometer...

Since the speed of sound is 360 m/s, 4 seconds will show that the strike
was about 1.44 km away while 3 seconds means that the lightning struck
at slightly more than 1 km away.

One mile equals roughly to 1.6 km's.

ml> what's really wild is seeing lightening flashes and counting and
ml> counting and counting and never hearing the thunder because it is so
ml> far away ;)

Yes that happens when the lightning jumps between clouds in the sky.
The flash is seen from very far away.

Have a nice day,

Holger

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