Mostly OT, lightning

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

As a self confessed coward when it comes to lightning, and one who
cowered in an isolated tent (fibreglass poles but on high ground )
last night in the middle of a particularly scary storm (and someone in
the West Midlands was killed today) are there any instances of
cyclists ever being struck? I'm sure they said cars were Ok on the old
QED program of the 80's but they have fatter tyres.

Cars are OK because you are enclosed in a metal shell, while the electrical
charge flows around the outermost layer of metal and into the ground. I
believe this is called "skin effect" or "mutual repulsion of charges".

If you sat in an isolated tent on high ground during a storm, you're braver
than I am. I would have packed up and headed for lower ground, someplace
where there were a good number of trees or tall structures nearby to attract
any lightning bolts away from me.
--
mark

mark said:

Cars are OK because you are enclosed in a metal shell, while the
electrical charge flows around the outermost layer of metal and into
the ground. I believe this is called "skin effect" or "mutual
repulsion of charges".

A car acts like a Faraday cage, as long as you don't touch internal metal
[1].

[1] which is pretty difficult to do in a modern car anyway

--
Kev

MartinM said:

Quoted message said:

are there any instances of cyclists ever being struck?

I'd imagine the rubber tyres will help you - at least more than standing on
the ground.

--
Kev

On Wed, 4 Aug 2004 01:01:31 +0100, Kevin Stone <[email hidden]>

Quoted message said:

MartinM said:

Quoted message said:

are there any instances of cyclists ever being struck?

I'd imagine the rubber tyres will help you - at least more than standing
on
the ground.

This was in the CTC magazine recently. Think the gist of what they said
was not to worry too much as there are a lot of things lightning finds
more attractive, but your best bet is to find a large group of trees and
shelter amongst the lowest ones, or take shelter in a large building.
I understand the electricity would easily jump the tyres.

Chris

--
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"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

As a self confessed coward when it comes to lightning, and one who
cowered in an isolated tent (fibreglass poles but on high ground )
last night in the middle of a particularly scary storm (and someone in
the West Midlands was killed today) are there any instances of
cyclists ever being struck? I'm sure they said cars were Ok on the old
QED program of the 80's but they have fatter tyres.

iirc a man (riding a bike) was killed a few weeks ago at a model aeroplane
display being held at an airfield in Lincolnshire. I think he had gone to
collect his plane when the storm started and was stuck out in the open.

Oh, here we are . . .
http://news.bbc.co.uk/1/hi/england/lincolnshire/3762613.stm

I used to love QED.

Regards

Paul F

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Quoted message said:

I'd imagine the rubber tyres will help you - at least more than standing on
the ground.

You think the little bit of rubber contained in a bicycle tyre is going to be
of help against the amount of charge in a lightning strike??

The best thing is to get to lower ground where you aren't the highest object
off the ground and seek shelter. If you can't you need to make yourself as low
to the gound as possible by crouching.

Cheers, helen s

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Kevin Stone said:

Quoted message said:

Quoted message said:

are there any instances of cyclists ever being struck?

Quoted message said:

I'd imagine the rubber tyres will help you - at least more than standing on
the ground.

Barely. The charge is such that it can jump through hundreds of feet of
air, so I don't think it'd have trouble covering an inch or so of wet
rubber. Even if the rubber were somehow impervious to lightning, the
charge could jump the air around the tyre.

If you're caught in a storm, imagine differently...

--
Mark.
http://tranchant.plus.com/

[email hidden] (MartinM) wrote in message news:<[email hidden]>...

Quoted message said:

As a self confessed coward when it comes to lightning, and one who
cowered in an isolated tent (fibreglass poles but on high ground )
last night in the middle of a particularly scary storm (and someone in
the West Midlands was killed today) are there any instances of
cyclists ever being struck? I'm sure they said cars were Ok on the old
QED program of the 80's but they have fatter tyres.

A cyclist was killed quite recently, see:

http://news.bbc.co.uk/1/hi/england/lincolnshire/3762613.stm

The tiny bit of rubber will not have any protective values at all!
--
Simon M.

Kevin Stone said:

mark said:

Cars are OK because you are enclosed in a metal shell, while the
electrical charge flows around the outermost layer of metal and into
the ground. I believe this is called "skin effect" or "mutual
repulsion of charges".

A car acts like a Faraday cage, as long as you don't touch internal metal
[1].

[1] which is pretty difficult to do in a modern car anyway

If it did act as a Faraday cage it wouldn't matter if you did touch the
internal metal but as it doesn't it does. Mark is right, the skin
effect confines the current to the outer skin of the metal shell.

People can be and have been killed in cars by lightning.

Tony

Kevin Stone said:

MartinM said:

Quoted message said:

are there any instances of cyclists ever being struck?

I'd imagine the rubber tyres will help you - at least more than standing on
the ground.

Another popular misconception. The lightning path is set up by the
static charges for which the rubber is irrelevant, the lightning strike
by dynamic currents for which the rubber is irrelevant.

Tony

dirtylitterboxofferingstospammers said:

The best thing is to get to lower ground where you aren't the highest object
off the ground and seek shelter. If you can't you need to make yourself as low
to the gound as possible by crouching.

Crouch in a low spot, feet close together and balancing on your toes,
head down and covered with hands together and elbows in touching the
knees. Then pray.

Most people are not killed by a direct lightning strike but by the
potential difference created in the ground by the currents flowing
outward from the strike - hence feet together to stop you getting
electrocuted by the voltage between you feet and tip toes to minimise
the contact area. Some people try to get really low by lying down - big
mistake.

The hands over the head minimise the head damage in a direct strike by
directing the current down the arms into the legs and the ground
avoiding the head and trunk where the damage is more likely to be fatal.

Tony

"mark" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

As a self confessed coward when it comes to lightning, and one who
cowered in an isolated tent (fibreglass poles but on high ground )
last night in the middle of a particularly scary storm (and someone in
the West Midlands was killed today) are there any instances of
cyclists ever being struck? I'm sure they said cars were Ok on the old
QED program of the 80's but they have fatter tyres.

Quoted message said:

If you sat in an isolated tent on high ground during a storm, you're braver
than I am. I would have packed up and headed for lower ground, someplace
where there were a good number of trees or tall structures nearby to attract
any lightning bolts away from me.

I did think about that, but waking kids up (yes they slept through it
amazingly) and dragging them into the car at 3am did not appeal, but
after hearing about the poor kid in his back garden will certainly do
next time.

in message <[email hidden]>, MartinM

(') said:

As a self confessed coward when it comes to lightning, and one who
cowered in an isolated tent (fibreglass poles but on high ground )
last night in the middle of a particularly scary storm (and someone in
the West Midlands was killed today) are there any instances of
cyclists ever being struck? I'm sure they said cars were Ok on the old
QED program of the 80's but they have fatter tyres.

This seems to come up regularly on this group, and people seem to me to
take the risk absurdly out of proportion. Yes, of course, you *can* be
struck by lightning while riding a bike. Someone last year was. But in
order to be struck by lightning you have to be the easiest path to
ground locally; in other words (because a human body on a rubber tyred
bike is not a spectacularly easy path to ground) you have to be higher
than anything else for a considerable radius around you.

The guy who was struck last year was in the middle of an airfield.

It's a bit like winning the lottery. It is possible, but I wouldn't
recommend relying on it.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; ... exposing the violence incoherent in the system...

Tony Raven said:

If it did act as a Faraday cage it wouldn't matter if you did touch
the internal metal but as it doesn't it does.

A car is not a perfect faraday cage (as non can actually exist in practice),
and since there are holes which allow paths for electric fields within the
'cage', since also as humans conduct elec, I certainly wouldn't recommend
touching it.

--
Kev

dirtylitterboxofferingstospammers said:

You think the little bit of rubber contained in a bicycle tyre is
going to be of help against the amount of charge in a lightning
strike??

Yes! Given the choice, I'll have the rubber please. Anything which makes the
path more resistant will increase your chances of not being hit.

--
Kev

Simon Brooke said:

This seems to come up regularly on this group, and people seem to me to
take the risk absurdly out of proportion. Yes, of course, you *can* be
struck by lightning while riding a bike. Someone last year was. But in
order to be struck by lightning you have to be the easiest path to
ground locally; in other words (because a human body on a rubber tyred
bike is not a spectacularly easy path to ground) you have to be higher
than anything else for a considerable radius around you.

Its not quite as easy as that. The path is chosen by the build up of
the electrostatic field. Which is why you should worry if your hair
starts to stand on end. Electrostatic fields are not too worried about
the resistivity of the materials - after all they are dealing with a few
hundred/thousand feet of insulating air - just in finding the shortest
path to earth. That field distribution will then dictate the line that
the leader will take and after that the main discharge takes care of any
resistivity by ionising the material in its path.

OTOH the risk is, as you say, relatively small - yesterday's lightning
toll was a fraction of yesterdays road toll.

Tony

in message <[email hidden]>, Tony Raven

(') said:

dirtylitterboxofferingstospammers said:

The best thing is to get to lower ground where you aren't the highest
object off the ground and seek shelter. If you can't you need to make
yourself as low to the gound as possible by crouching.

Crouch in a low spot, feet close together and balancing on your toes,
head down and covered with hands together and elbows in touching the
knees. Then pray.

Easy on the hysteria, guys.

Your chances of being struck by lightning as you stand on the top of a
hill in the worst thunderstorm imaginable are substantially less than
your chances of being killed by a car as you cycle down a suburban
street. Do you 'pray' when you cycle down a suburban street? Of course
you don't. Cars are a risk we're familiar with. Lightning is a risk
we're less familiar with. But it still isn't much of a risk.

I don't much like sailing in thunderstorms because it means I'm sitting
at the bottom of a ten metre metal pole which categorically is the
highest thing often for many miles around. But I've done it many times.
I've *heard* of boats being struck by lightning, but I've never seen a
boat that's been struck by lightning, and as far as I know I've never
met anyone who has. And the risks of boats being struck by lightning is
(for the reasons I've given) several orders of magnitude higher than
the risk of bicycles being struck by lightning.

Yes, it could happen. You could win the lottery. And all the molecules
in your hostesses undergarments could suddenly jump one metre to the
left. But, uhhhmmm, don't hold your breath.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

IMHO, there aren't enough committed Christians, but that's care
in the community for you. -- Ben Evans

Kevin Stone said:

Tony Raven said:

If it did act as a Faraday cage it wouldn't matter if you did touch
the internal metal but as it doesn't it does.

A car is not a perfect faraday cage (as non can actually exist in practice),
and since there are holes which allow paths for electric fields within the
'cage', since also as humans conduct elec, I certainly wouldn't recommend
touching it.

Its not a question of whether its a Faraday cage or not - Faraday cages
deal with static electricity and form an isopotential within them. Yes
the windows may cause some field fringing but a car will still be
essentially isopotential inside for static charges - cabriolets and
plastic bodied cars excluded.

A lightning strike is not static electricity - its essentially a half
cycle of AC current. You could stand inside a closed metal box and get a
shock from a lightning strike that you would not get with a static
charge. The only reason you are protected is that AC currents have a
thing called skin depth which restricts the current to flowing on an
outside sheath of the car bodywork and not on the inside. With a
thinner bodyshell or a lower frequency that would go away and the
protection would be reduced.

Have a look at the "Touching Lightning" section of the Boston Museum of
Science's Theater of Electricity web site for more details:
http://www.mos.org/sln/toe/toe.html

It also explains why you are wrong about tyres.

Tony

Simon Brooke said:

Easy on the hysteria, guys.

Your chances of being struck by lightning as you stand on the top of a
hill in the worst thunderstorm imaginable are substantially less than
your chances of being killed by a car as you cycle down a suburban
street. Do you 'pray' when you cycle down a suburban street? Of course
you don't. Cars are a risk we're familiar with. Lightning is a risk
we're less familiar with. But it still isn't much of a risk.

Agreed but like cycling it helps to know what to do if you are cycling
down the high street (primary position etc) or caught out in a
thunderstorm (as above) to minimise the risk.

You chances of being struck are significantly lower mainly because most
people don't stay out in a thunderstorm and there are only a few days of
storms a year. On an exposure basis its probably about equals.

Tony