[USMA:35438] Lightning and thunder

[Pat Naughtin]

Title: Lightning and thunder

Dear All,

Yesterday, there was a summer storm that went past us near Geelong. Sometimes we saw the lightning and then heard the thunder and at other times we just heard the thunder.

I used the time honoured technique of counting seconds (one thousand, two thousand, three thousand . . .) to estimate the time interval between lightning and thunder and then divided the time interval by 3 to estimate our distance from the storm in kilometres. This technique is based on the idea that the speed of sound in air is about 340 metres per second — or about one kilometre in three seconds.

However, I soon realised that this seemed to be only useful for a distance a bit over 3 kilometres (. . . nine thousand, ten thousand . . .) as I didn’t have an instance of anything longer. Perhaps this was just a property of this particular storm.

But this experience posed the following questions in my mind and I thought that someone on this list might be able to answer them.

>From what distance can lightning be seen?

>From what distance can thunder be heard?

Cheers,

Pat Naughtin
PO Box 305 Belmont 3216
Geelong, Australia
61 3 5241 2008
[EMAIL PROTECTED]
http://www.metricationmatters.com

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