Lightning - Electrics, Hammocks And The 30/30 Rule

[Moonraker]

Just read this story about using electrical items during a thunder storm and thought to post it here to remind people of the potential dangers. I love watching storms a lot but with the caution they deserve. In this case it was a mobile phone being used in a London park:

Warning: mobiles and lightning don't mix

and another one involving the use of an iPod music player:

Lightning lashes iPod-packing teenager

To put it into some kind of context, according to the U.S. National Weather Service, 73 people die from lightning strikes each year and hundreds more suffer life-debilitating injuries.

National Geographic have a really good article on this subject with lots of detail and advice which can be found here:

Key to Lightning Deaths: Location, Location, Location - 2004

It highlights a potential issue in bushcrafting, where carrying metal objects (knives, axes, rucksacks, large metal zippers on clothing etc.) is common practice and perhaps suggests that such items need to be removed during such an event if possible to minimise the danger.

Also, it made me consider the danger of being in a hammock between two trees if one gets struck

Apparently there has been at least one death in such a case just last month in the States:

Man found dead in camp hammock; lightning suspected - Sunday, June 25, 2006

And an account of the same incident from the New York Times:

A camper who was struck by lightning on Friday while resting in a hammock died over the weekend, the police said. They said that the man, who was 59 and from Holmdel, went kayaking on Friday at the Round Valley Reservoir and spent the night nearby in a hammock anchored to trees. Several thunderstorms moved through the area during that night. An autopsy will be done to determine the exact cause of death, the officials said. "It appears from what we can tell at this point that lightning struck the tree, struck the ground and hit him," Deputy Chief Sam DeBella of the Hunterdon County prosecutor's office told The Courier News of Bridgewater.

source: NY Times-Man Struck by Lightning in New Jersey Dies - June 26, 2006

Most important is the advice they included from the US National Weather Service:

Lightning Safety

To avoid death by a flash of lightning, the National Weather Service recommends following the "30/30" rule. When lightning is seen count the time until thunder is heard. If it is 30 seconds or less, seek shelter immediately and stay there for at least 30 minutes after the last rumble of thunder is heard.

"Typically, people go out and resume activity too quickly and end up getting hit," said Hodanish.

Covered picnic shelters, tents, and convertibles even with the roof up are not safe. Rakov said that shelter should be a substantial building such as a home or inside a car with a metal roof.

"If neither are available, make yourself as small a target as possible," he said. "Never stand near tall trees, metal fences, or water." Metal objects are popular targets of lightning and power lines can conduct lightning surges over large distances, he added.

According to Hodanish, who is working on a scientific paper about a man who was struck and killed by the first lightning flash of a storm on top of Colorado's Pikes Peak, "for some, no matter what precautions you take, you can be the unfortunate victim of lightning."

Be Safe Out There...

 

[janiepopps]

Cheers for getting all that info together Moonraker, I've been meaning to wise up on it after spending last weekends storm in a tent on Dartmoor :yikes: Apparently 92 sheep were killed in that storm whilst taking shelter under a tree!

I was lucky enough to have the car there, but I guess if you were out on your own it could be interesting. Didn't know you were supposed to remove metal objects either.

Thanks again mate :You_Rock_

j

 

[RHGraham]

I have a brother-in-law who is a meteorologist here in my area and it's his professional opinion that carrying your metal equiptment really has no bearing on it at all, since the items themselves are not grounded individually, it's still the body ittself in contact with ground.
The vast majority of human lightening strikes are secondary... a tree or other tall object close by is struck initially and the person gets zapped by way of proximity.
In the cases where it's a direct strike it's usually indicated that the person was in an opening or space where they were the sole tallest object.

In campgrounds it's sometimes the tent-poles that are struck also, since they can be often in direct contact with the ground.

In the case of the phone and Ipod he's very skeptical that it could have been those objects themselves responsible for attracting lightening, moreso once the arc was already established in the zone in which the person was standing then it's a matter of the lightening making contact with the highest/best spot on the person to ground.... meaning, the strike was already determined, the fact that it may have contacted the phone or the ipod initially may have been a moot point.

Fact is, folks just don't get under cover during lightening like they should, and this is really the problem. It's not uncommon to hear about a strike in a campground or a city in particular where the people were actually out watching the lightening.

Get inside a building, a vehicle, or at least the lowest area you can find nearby and it will reduce your likelyhood of being struck. The equiptment you are carrying will have very little bearing at best, and likely none.

 

[mark a.]

I agree. Someone got struck by lightning while on the phone or listening to their iPod, then the media creates a causal link (got struck because of the phone) for no real reason.

Let's see - 1 person gets hit by lightning when listening to their iPod. Hundreds of people get struck by lightning when not listening to iPods. Judging by statistics alone, perhaps we should all wear iPods when out in thunderstorms!

 

[stevec]

there is some interesting info in lofty wiseman's book about this i think, ie not being near to a hil, no sheltering in a cave etc!

30 seconds gap, so thats about 6 miles away by my reconing.

speed of sound 320-340 m/s so sound travels a mile in roughly 4.7-5 seconds.

interestin stuff

 

[Wills]

I heard a theory at school from a physics teacher that if you are caught out in a field then the best thing to do is get on all fours and shove your backside in the air
The theoretical madness being that the current will pass through the legs/ torso.

Bonkers if you ask me

 

[davef]

Na I think your teacher was just trying to win the "most embarassing position to be found dead in after a lightening storm" competition.... or trying to get a Dawin Award nomination!

 

[Adi]

As a bit of a lightning - thunderstorm fan i enjoy getting out in the storms and taking photos and video footage.

Last year i watched French import storm cross the channel in a spanish plume all day on sferics and radar. Most were passing to the west of the Isle of White so i could only see them ion the distance.

As last light began to fall i notice on radar that there was a cell which looked to track to the east of the Isle of White, the sfarics confirmed it was an an active cell and i knew it was going to intensify as it made landfall. I headed down to Langston harbour to get photos of the storm as it passed near by. I Expected the storm to pass over Chichiest harbour. I got to the location and set up and watched the storm approach, my position did not alow me to take photos whilst the storm was out to sea, I needed to wait till it had moved in land which suited me as i wanted the storm to intensify. I then saw lightning over the Hayling ferry which worried me as i did not expect to see it there. Then it started to rain and it was then i realised i was the cell was going to pass directly overhead. The rain got really heavy and i started to try and get photos of the lightning but had to shield my camera from the rain. The lightning was out of this world and relentless. I watched it striking boats, the sea and buildings on Hayling Island. It struck the traffic lights some 40 meters behind me, Portsmouth collage about 80 meters behind me. Then whilst i was taking a photo there was huge rush of air past me a blinding flash and a bang that nearly knocked me over. Lightning had struck the beach meters in front of me i actually saw it shoot across the ground towards me, thank god it did not reach me. At that point i decided to pack up the camera kit and sit the storm out before going home. The storm lasted for two and a half hours and that day was one of the highest lightning active day last year. The image below is the one right in front of me unfortunately i managed to get a lot of my hand trying to shield the camera from the rain.

If you are caught in a storm and there is cloud to ground lightning in your location. Sit down on a bag or something if possible tuck your legs up so your knees are at your chest and your ankles are tucked in to your bum. tuck your head down and hold onto your ankles. By sitting like this you are shielding all your vital organs and if lightning strikes it will pass through your back, arms and legs into the ground.

Don't hang out of a bedroom window or stand in the doorway watching a storm because if the lightning strikes your house it will travel down the walls and when it reaches a gap it will leap across and into you if you are in the gap.

If you are in a car stay in it and dont touch the metal.

The biggest risk whilst using a phone is not from electrocution but thermal shock a high piched crack that can blow your ear drum out.

 

[MattW]

Yep - I've always been told that it all boils down to just not making yourself a target - i.e. don't make yourself the highest point on the landscape and don't think that being under a tree will shelter you (if the top of the canopy is struck, the strike will often flow around the periphery of the canopy and earth itself to ground via the person standing under the canopy, rather than the trunk). You are better of just lieing flat on the ground away from the trees.

Also, due to the nature of high voltages, most of the conduction takes place in the outside of the conductor, so if inside a building / car don't lean on the wall.

One final thought is that most ground strikes actually involve two discharges, the first being an often invisible discharge which goes from the ground to the cloud. This ionises a path from the earth to the high potential cloud, through which the main strike travels down to the earth. So in effect, lightning strikes upwards!

Matt (who rather likes meteorology )

edit: our posts crossed Adi - cool pics!

 

[Adi]

Lightning Safety

To avoid death by a flash of lightning, the National Weather Service recommends following the "30/30" rule. When lightning is seen count the time until thunder is heard. If it is 30 seconds or less, seek shelter immediately and stay there for at least 30 minutes after the last rumble of thunder is heard.

"Typically, people go out and resume activity too quickly and end up getting hit," said Hodanish.

Covered picnic shelters, tents, and convertibles even with the roof up are not safe. Rakov said that shelter should be a substantial building such as a home or inside a car with a metal roof.

"If neither are available, make yourself as small a target as possible," he said. "Never stand near tall trees, metal fences, or water." Metal objects are popular targets of lightning and power lines can conduct lightning surges over large distances, he added.

According to Hodanish, who is working on a scientific paper about a man who was struck and killed by the first lightning flash of a storm on top of Colorado's Pikes Peak, "for some, no matter what precautions you take, you can be the unfortunate victim of lightning

The 30/30 rule is a very important rule and is the main rule in the US. The reason it is so important is that lightning can travel 10 miles from the Storm cell and this takes 30 seconds so if you are within that 10 miles you are at risk. I dont recall the actual distance but 3 golfers were killed in the US and it was just over ten miles to the storm cell. The cheapest lightning detectors start recording lightning strikes 40 miles and all outdoor sports and activities in the US have to start packing up and taking shelter when the detector starts going off.

It highlights a potential issue in bushcrafting, where carrying metal objects (knives, axes, rucksacks, large metal zippers on clothing etc.) is common practice and perhaps suggests that such items need to be removed during such an event if possible to minimise the danger

This is often advised but there is little evidence that lightning is attracted to metal any more than it is attracted to us. Metal objects can glow blue and hum which is amazing to experience, if you feel threatened by this just lay the metal object down on the ground near by.

Lightning is not attracted to an object. all objects sticking above the ground give of positive ions in the for of a streamer attracted in to the sky, the thunder storm releases a stream of negative ions which are attracted to the ground in the form of a step leader. When this step leader meets the streamer you get the lightning.

 

[anthonyyy]

I was told by an electronics lecturer that if you going to touch something which might give you a shock;

"use your right hand and stand on your right leg."

The theory is that the current takes the shortest route to earth and in this posture you are protecting the heart.

So, if you stuck out in a thunderstorm; put your right hand in the air and hop on your right leg.


Even if it ise'nt effective against lightning strikes it will protect you from muggers as they will be scared to go near you.

 

[fred gordon]

I thought getting down on all fours and sticking your backside in the air was all to do with how to make an emergency cycle rack!

 

[Moonraker]

Nice to get plenty of feedback on this.

One the point of whether the metal objects attract the lightning, it is not just this that the article refers to. It is more the effect any metal (or water) has on the flow of electricity across the body.

.....When a person is hit by lightning, the high resistance of human skin causes the lightning charge to flow over the body - often known as an 'external flashover'.

But some of the current can flow through the body. The more that flows through, the more internal damage it causes.

Conductive materials in direct contact with the skin such as liquid or metal objects increase the risk that the current will flow through the body and therefore cause internal injury.

source: BBC - Mobile phone risk during storms. 22 June 2006

agree. Someone got struck by lightning while on the phone or listening to their iPod, then the media creates a causal link (got struck because of the phone) for no real reason.

Let's see - 1 person gets hit by lightning when listening to their iPod. Hundreds of people get struck by lightning when not listening to iPods. Judging by statistics alone, perhaps we should all wear iPods when out in thunderstorms!

In a sense you are right mark a., as the ipod conducted the charge away from the chest area (via the headphone lead) and might have aided their survival.

If you don't trust the media then perhaps the British Medical Journal:

In the British Medical Journal, they highlight the case of a teenager left with severe injuries after being struck by lightning when talking on her phone.

The metal in the phone directs the current into the body, they say.

source: see link above to BBC article. BMJ article reference is: 'Injury from lightning strike while using mobile phone'. Esprit et al. BMJ.2006; 332: 1513

The main point was on basic avoidance or reduction of the risk posed by lightning and how it may relate to bushcraft activities. I think the risk when hammocking is potentially that much greater given that wet rope is an excellent conductor and it would be attached to trees.

There is some good, detailed information here too from the American Meteorological Society specifically for outdoors situations:

Lightning Risk Reduction Outdoors

There advice included if you have no safe location nearby is:

Do NOT seek shelter under tall isolated trees. The tree may help you stay dry but will significantly increase your risk of being struck by lightning. Rain will not kill you, but the lightning can!

Do NOT seek shelter under partially enclosed buildings
Stay away from tall, isolated objects. Lightning typically strikes the tallest object. That may be you in an open field or clearing.

Know the weather patterns of the area. For example, in mountainous areas, thunderstorms typically develop in the early afternoon, so plan to hike early in the day and be down the mountain by noon.

Know the weather forecast. If there is a high chance of thunderstorms, curtail your outdoor activities.

Do not place your campsite in an open field on the top of a hill or on a ridge top. Keep your site away from tall isolated trees or other tall objects. If you are in a forest, stay near a lower stand of trees. If you are camping in an open area, set up camp in a valley, ravine, or other low area. A tent offers NO protection from lighting.

Wet ropes can make excellent conductors. This is BAD news when it comes to lightning activity. If you are mountain climbing and see lightning, and can do so safely, remove unnecessary ropes extended or attached to you. If a rope is extended across a mountain face and lightning makes contact with it, the electrical current will likely travel along the rope, especially if it is wet.

Stay away from metal objects, such as fences, poles and backpacks. Metal is an excellent conductor. The current from a lightning flash will easily travel for long distances

If lightning is in the immediate area, and there is no safe location nearby, stay at least 10 feet apart from other members of your group so the lightning won't travel between you if hit. Keep your feet together and sit on the ground out in the open. If you can possibly run to a vehicle or building, DO so. Sitting or crouching on the ground is not safe and should be a last resort if a enclosed building or vehicle is not available.

 

[Ben Trout]

Typically before a strike a number of 'risers' build up, risers being the coloums of ionised air mentioned. The main strike will 'choose' one of the risers, whichever is the path of least resistance. The phenomenon of glowing, humming and sparking of metal objects that Adi mentioned is a sure sign of being in a riser and hence having a high risk of taking a strike. Adi, if you've seen this a number of times then I conider you to be very lucky! The course of action you suggest is much the same as MLTB teaches. If you can get a look at the ML book, it covers lightning safty in some detail.

 

[Wills]

Moonrakers post has reminded me of something I learnt whilst completing my electrical apprenticship.

If a high voltage overhead cable comes into contact with the ground then feet should be kept together to reduce the potenial difference :yikes: . Also if you were in a digger, you should jump clear and land with both feet together. It was taught to us as part of electrical safety, building sites in particular.

I didn't know that lighting could still arc and get you even though it hasn't actually struck you!

The power in nature never fails to amaze me.

 

[Adi]

Ben Trout, in deed streamers are a worry but recent research has found that all objects above ground level give off streamers under the storm cell.

I would advice that people avoid going out in storms especially to photograph or film them. When i am out photographing them i try to position myself in the updraft region of the storm which is located to the south of the cell. I have a very good understanding on what is going on and can recognise important changes in the cloud and can recognise the different types of storm cell. I also have access to the most up to date weather data and have experience of interpreting it and I still get it wrong at times.

I didn't know that lighting could still arc and get you even though it hasn't actually struck you!

Yeah i have watch it strike cranes down the docks but still carry on to the ground but not follow the crane. Two girls were killed in one of the parks in central London one evening when lightning struck a tower block and arced at a 45 degree angle from the building hitting a tree they were walking past. some 300 meters from the building, That was in 2004 or 2005 and reported in the news.

 

[Ben Trout]

Adi, glad to hear that you know more than me! Nice pictures further up the page, too.

 

[Adi]

Adi, glad to hear that you know more than me! Nice pictures further up the page, too.

I dont think its a case of knowing more, your posts have demonstrated that you have good knowledge of the subject.

 

[nickg]

I once watched an artillary officer on hohne ranges in germany get hit by lightning. It blew him about 30 feet across the tarmac. He survived the combats he was wearing were totally drenched and caused the discharge to track down the moist outside of his clothing. I found his beret - it had two charred black pinholes (red Para Beret) presumably where it hit. The whole strike took milliseconds, does anybody really thing that he would have time to put both feet on the ground - or raise one foot and one arm - Sorry guys thats B*****ks.
He was surrounded by a load of centurian Mk5 tanks, 8 of them, all fully ammo-ed up and fully fueled with 220 gals of petrol, all soaking wet and solid metal (not even rubber track pads) and all at least 13 feet high not counting radio antennas, so much for making yourself small. He had rubber soled boots on, so much for insulation. 30/30 rule, guys there are places in Cumbria that would keep you indoors for a week if you went by that maxim.
Dont jump off a vehicle if power lines fall on it - if it didnt explode on contact then sweat it until they stop crackling and then get off (after the trips in the sub-station have kicked out which they will do). Honestly I have seen an arc through a squaddie who jumped off a bridgelayer with power lines draped on it (he survived with some 2nd deg burns).
Dig this subject up on the web and you will find people who have been struck inside their houses, people who have been struck 20 times ( in fact statistically the chances of bieng struck twice are HIGHER than the odds of bieng struck a first time.
I really dont know what the logicial probability of a strike is nor how to really avoid it but i would take some of the ideas here with a large pinch of salt.
I DO know that standing under a tree is a BAD idea since if the tree is srtuck the moisture content of the sap will turn to steam and explode sending masses of splinters and scalding jets of steam for at least the spread of the branches distance, assuming of course that the whole b***dy tree doesnt fall on you.
Sleep tight.

 

[RAPPLEBY2000]

so given a fairly standard bushcraft scenario:
you're in a large wooded area prehaps miles from "SAFE"shelter
(lets say you hiked there!)
you have a standard tarp or poncho,
natrual leaf shelters,
and a hammock

what is the best option to the bushcrafter?

do you run, laydown, or get in one of the above shelters?

would a aluminium lined sheet or tin foil offer any form of protection if you made it into a Faraday cage?(electric cage?)