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Lightning storm

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Ady126/07/2018 23:13:12
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3463 forum posts
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Just had a cracker go over Edinburgh, non-stop forked lightning firing out all over the place but it was almost silent, just a distant rumble even when directly overhead

Never seen anything like it in me life, quite beautiful

not done it yet27/07/2018 05:42:28
3372 forum posts
11 photos

Overhead? How high? Sound travels a mile in about 5 seconds, and is usually audible from up to 3 miles distant, or more.

Lightning cannot be quiet unless a feeble spark. Think you need to put your hearing aid in or your house is tripple glazed!.smiley

Nige27/07/2018 07:31:41
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370 forum posts
65 photos

Ady1: During one of my frequent nocturnal micturation episodes I noticed the same thing here in Peterborough, lots of lightning from many directions and very little noise. It was a strange enough experience to raise my awareness from somnambulant to almost half asleep 😊

Brian Wood27/07/2018 08:50:55
1966 forum posts
37 photos

I stood in a garden in Luton many years ago and watched a similar display, sweeping up from the south and racing north overhead. Just a steady grumble all the time, rather eerie.

Brian

Ron Laden27/07/2018 09:01:08
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1363 forum posts
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We had a storm back in April with forked lighting all over the place, I was stood outside watching it and that didnt have a lot of sound, maybe it depends on the type of lightning.

Edited By Ron Laden on 27/07/2018 09:01:39

Gary Wooding27/07/2018 09:05:05
582 forum posts
138 photos

I recall a similar thing in London some 60 odd years ago. The radio (wireless?) next day described it as a unique tropical electrical storm.

SillyOldDuffer27/07/2018 09:16:12
4719 forum posts
1010 photos

I've noticed the contradiction as well. Thunderstorms usually go 'flash, pause, bang', but sometimes you just get the flash, or - more rarely in my experience - a bang.

My guess is sound doesn't behave like light. Unlike the flash, the bang bounces off the ground and layers in the air creating dead spots. Also, when the bang arrives at your ears, it may have followed more than one route (direct plus a bounce) which might also cause dead spots and places where the noise is extra loud.

Does anyone know if the bang is equally distributed along the lightning bolt? Or is it concentrated at one end or in the middle? My guess is that most of the sound occurs near ground level where the air is thicker, which would make a difference to bounce effects.

Dave

Ady127/07/2018 09:40:27
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3463 forum posts
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It was all firing into the cloud above me which was a 10 minute flash raincloud with no groundstrikes

A layman might describe it as a high altitude lightning supercell, would have been utterly terrifying at ground level

Just a steady grumble all the time, rather eerie.

Brian

It was just that, and fabby forked lightning

Ron Laden27/07/2018 09:45:29
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1363 forum posts
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Talking of lightning/thunder storms, I live right next door to the village church and last year we had a mother of a storm travel straight over the top of us. We were sitting indoors and suddenly there was what can only be described as an explosion, as if a huge bomb had gone off.

The next morning it turned out that the church tower had taken a direct hit, the cap on the top of the flag pole was blown off as was the top parts of the weather vane. Two weeks later and talking to one of the electrical engineers doing the repairs, they found the revolving part of the vane was welded solid. The tower is fitted with a copper earth strap but the engineer said that they are not guaranteed to prevent damage. The church had to be re-wired as the wiring was wrecked with wall lights and sockets blown out of the walls but fortunately no fire.

The engineers theory was that the lightning struck the wet painted flag pole (the highest part of the church) travelled down and did its damage before the earth strap came into play. There was also structural damage to the top of the tower.

Just shows the power of an electrical storm, quite scary.

Edited By Ron Laden on 27/07/2018 09:49:17

Maurice27/07/2018 10:06:26
443 forum posts
50 photos

I doesn’t need a direct hit from lightning to do considerable damage . Induction is enough. When I started working for the G.P.O. Many years ago, most of the phone lines were fed by overhead lines on poles, sometimes for miles. A nearby strike would be enough to leave just a scorch mark on the walls in the house where the internal wiring ran, and the induction coil in the phone would burst. Quite expensive.

Martin 10027/07/2018 12:05:09
250 forum posts
6 photos

One of the 'unique ' features of the storm that destroyed the roof of York Minster back in 1984 was lightning without any sound of thunder

Alan Vos27/07/2018 19:08:40
136 forum posts
7 photos
Posted by not done it yet on 27/07/2018 05:42:28:
Lightning cannot be quiet unless a feeble spark.

Yes and no. I was once in the right place at right time to have my attention attracted by a leader reaching a nearby (75m?) high tower roundabout light. That was quiet. What happened next was not.

Mick Henshall27/07/2018 19:30:35
519 forum posts
29 photos

Isn't there a " Blood Moon " tonight ( whatever that is ) no rain or thundery stuff in my part of Dorset yet

Mick

Muzzer27/07/2018 19:34:33
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448 photos

As I understood it, lightening conductors are not intended to withstand a direct "bolt" of lightening. Instead they are designed to spray electrons into the electric field and thus sort of disarm it, thus preventing a strike in the first place. The top of the conductor is generally spiked / pointed, to increase its effectiveness in that regard. If lightening actually strikes one of these, it may well blow / vaporise the strap.

Perhaps a lightening conductor expert will be along presently....

Murray

Alan Vos27/07/2018 20:47:15
136 forum posts
7 photos
Posted by Muzzer on 27/07/2018 19:34:33:

As I understood it, lightening conductors are not intended to withstand a direct "bolt" of lightening. Instead they are designed to spray electrons into the electric field and thus sort of disarm it, thus preventing a strike in the first place.

Not an expert, but that would be a lightning deflector. My understanding is that the purpose of a lightning condutor is that *IF* your structure is hit, to conduct the current round the structure rather than through it, reducing the damage.

not done it yet27/07/2018 20:51:57
3372 forum posts
11 photos

Lightning conductors are just that - conductors of electricity. However, they are limited and there should be no sharp bends in the - particularly 90 degree corners - because the extreme electrical pulse can travel straight on at a corner and pass through the building structure causing quite severe damage (although better than no conductor at all).

Lightning conductors are actually designed not to be struck - that is the last resort defence and often means they need checking ans some replacement - but to discharge the electrical charge before the voltage builds up sufficiently to strike an arc in the atmosphere. A ‘whooshing’ sound in that scenario - but I would not recommend anyone sitting next one to find out!

That is why the end of the item is a pointed spike (back to physics at school and why Van de Graaph generators have round spheres and not sharp spikes).

richardandtracy27/07/2018 21:01:56
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938 forum posts
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I can remember putting an ammeter in a conductor at school. It was a rumbly day, and registered 10 amps with the sky positive. Very surprising,

Regards

Richard.

Muzzer27/07/2018 21:09:38
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2904 forum posts
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Sounds as if both mechanisms are expected but clearly it's controversial even after many years. Seems it's not even agreed if pointy or rounded tips are best.

Here's a bit more about it, this focusing on CTS ("charge transfer system" to reduce the probability of a strike to begin with. Presumably they have a commercial agenda...

Murray

mark costello 127/07/2018 21:15:18
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541 forum posts
12 photos

Do You have heat lightning over there?

martin perman27/07/2018 21:21:18
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1657 forum posts
67 photos

This afternoon we had a thunderstorm with all the sound but no flashes above our heads

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