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This is just a fun with physics type of question. Seeing that both the speed of sound (In air) and the speed of light are a known constant is it possible to measure the amount of time between you seeing the flash of light from the lightning and hearing the thunder clap and then deduce how far the lightning struck from you?

Now this could happen in a 360 degree circle from you. So maybe a bit hard to deduce where exactly the lightning struck, but is it possible to get tot the distance?

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    $\begingroup$ Yes. This is a standard thing done for those who want to play with this. You might have some uncertainty from the loud part being above ground rather than at ground level. $\endgroup$
    – naturallyInconsistent
    Commented Jul 7, 2023 at 9:06

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Sure. Sound travels through air at roughly $340$ m/s under standard conditions. Light travels so quickly that for all intents and purposes you can consider the flash from the lightning to arrive instantaneously. Therefore, if the time between the flash and the boom is $T$ seconds, then the distance from you to the lightning strike is roughly $340\cdot T$ meters. Alternatively, it takes sound $4.73$ seconds to travel 1 mile through ambient air, so as a loose estimate the distance (in miles) between you and the lightning strike is equal to the number of seconds between the flash and the boom divided by 5.

Of course, as mentioned by user @naturallyInconsistent in the comments, this distance is really the distance between you and the origin of the sound, which I would imagine to be the nearest part of the strike path to you (after all, lightning strikes can take very complex paths, and need not even terminate on the ground).

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To complement the excellent answer by J Murray, I would add that one of the reasons why the sound of the thunder lasts much longer than the flash of the lightning is precisely because the lightning flash is very spread out, so the sound from all of the different parts of it takes a different amount of time to reach your ear, hence you hear a protracted rumble rather than a short sharp bang.

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    $\begingroup$ also because of echoes off mountains (or buildings depending on where you live) $\endgroup$
    – AXensen
    Commented Jul 7, 2023 at 10:32
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    $\begingroup$ Complimentary to all the aforementioned reasons, the fact that the phenomenon is well into the non-linear acoustics regime introduces some dispersion (frequency-dependent speed of sound), at least for the first moments (close to the lightning) which could (most probably to a lesser extent though) to the spreading of the thunder. $\endgroup$
    – ZaellixA
    Commented Jul 7, 2023 at 10:43

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