Why being in a car during a lightning storm is the safest place to be
As watcher of weather, both as as a one-time storm chaser as well as a person who gets sent email about weather of all kinds, I’ll have to say I’ve never seen anything like this video. The National Weather Service lighting safety page reports that a person’s odds of being struck by lightning are around 1 in 775,000 at any given time with 1/10,000 in an 80 year lifetime. Capturing the event live on video has to be even higher odds.
A police car dashcam captured footage of a direct lightning strike the roof of a Toyota Landcruiser carrying a senior Russian official on a rainy Russian day – while driving down the freeway.
I was even more struck by the odds of the lightning hitting the SUV while there are taller light poles along the freeway and taller buildings in the vicinity. It was just a case of being in the wrong place and the wrong time.
While the internal electronics for the SUV are possibly fried, the occupant wouldn’t be.
So why is being in a car during a lightning storm is the safest place to be? Two words – Faraday Cage. From Wikipedia:
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks external static and non-static electric fields. Faraday cages are named after the English scientist Michael Faraday, who invented them in 1836.
A Faraday cage’s operation depends on the fact that an external static electrical field will cause the electric charges within the cage’s conducting material to redistribute themselves so as to cancel the field’s effects in the cage’s interior. This phenomenon is used, for example, to protect electronic equipment from lightning strikes and electrostatic discharges.
A Faraday cage is best understood as an approximation to an ideal hollow conductor. Externally or internally applied electromagnetic fields produce forces on the charge carriers (usually electrons) within the conductor, generating electric currents that rearranges the charges. Once the charges have rearranged so as to cancel the applied field inside, the currents stop.
If the cage is grounded, the excess charges will go to the ground instead of the outer face, so the inner face and the inner charge will cancel each other out and the rest of the cage will retain a neutral charge.
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Note: The SUV has steel belted radial tires, and thus is essentially grounded as lightning easily jumps that dielectric gap.
h/t to WUWT reader Newton Love
Cool. Been hit by lighting in an aircraft. They are an effective Faraday cage too. (As long as
the staic wicks are intact…) I would rather ride through a thunderstorm in a car however than
have that exquisite moment that you suddenly realize that you are about to go for an interesting ride. Especially when the cloud that you are in has turned a dark, sickly green…
Airplanes get struck by lightning on the ground and in-flight, damage is rare. Very high metal to glass ratio, so a reasonable “Faraday cage”. Not sure I’d want to try that in an SUV.
I haven’t seen a capture as good as this either, but I can tell you the odds of capturing all sorts of freak events in Russia are much higher than elsewhere because everybody there rides with a dash cam or a helmet cam constantly recording, collecting evidence for legal purposes, just in case (it is a wild country).
I wonder [how] a car with a fibreglass or carbon fibre body would cope?
Top Gear did a good segment on this…
http://youtu.be/GZxgYNnkBd0
I instruct navigators part time. We have a video taken at an airport in Japan where lightning strikes an aircraft shortly after take-off. It enters at the front and exits near the rear.
Last year an aircraft landing in Winnipeg was struck by lightning. passengers were not injured, but somewhat shook up.
With respect to a car, I heard (correctly?) that if you keep the windows closed you should be OK if lightning strikes.
Putin trying to prune the ranks? Running out of polonium?
RE: mwhite says:
September 27, 2012 at 7:53 am
I wonder [how] a car with a fibreglass or carbon fibre body would cope?
A good question. The new airbuses are also composite. I trust (but do not know) that they are embedding metal to carry the electrical strokes. Some new ones are 25-50 percent composite.
Not sure what they are doing to cars as the composites offer more resistance and I would expect would sustain more damage.
It’s happened to me twice, once travelling down through France during a terrible storm in a Renault 4 many years ago – we got hit repeatedly and finally stopped under the next bridge to take shelter. Then years after I got caught in a storm in Chelsea, London, with my dog. We got back in the car and it got hit – we were ok but it was scary (and the dog who hadn’t been fazed by thunder and lightening until that point) was always a basket case in a storm ever after.
Both times lightening was coming down and hitting the ground repeatedly. It’s something to see! The worst storm of that sort I ever saw was in Italy – it was right on top of us, a late summer storm, and I had two horses at livery in a field at a hilltop farm. The lightening was hitting ground in the field over and over, all around them – the poor things were terrified but I’d have had no chance of catching them even if I’d dared venture out. It was also hitting the house, and coming down via my bedroom light fitting, finding a corner, and whizzing round the room before finding a way out and down. I was in bed with the dog and cats, cowering under a duvet. I’d thought the house was earthed….
Gene that’s very interesting!
I nearly got fried on a golf course in Venezuela once…
We should build a Faraday cage around the Earth for the next Carrington Event…
@tgmccoy says:
September 27, 2012 at 7:37 am
Saw that dark sickly green over Savannah one night in 1972. Also green 2Lt at the controls of a mighty O-2. Fortunately he flew the checklist (thunderstorm penetration airspeed and all that) and got himself and one shaky Staff Sergeant (me) on the ground safely.
Rarely I’ve been very close to a lightning strike. It’s usually proceeded by a slight flash & snapping sound, then a fraction of a second later, the real bolt. Ear-drums can be busted…
I was in my car once when it got hit by lightning. The wiring was fried, but I felt nothing.
I did get shocked once holding a (land line) phone during a thunderstorm. Not as strong as an electrical outlet shock, but it was startling.
OT: The Wikipedia page of Marcel Leroux is under attack by some zealots.
http://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Marcel_Leroux
To those here who have read his work, help would be appreciated.
I have several Faraday flashlights that work quite well. Not sure I want a Faraday SUV. Yikes!
In April 1999 a two seat all GRP training glider (ASK21) was struck by cloud to cloud lightning when at approximately 2,500ft above the ground and several hundred ft above cloudbase. The airframe disintegrated on or immediately after the strike, the pilot (an acquaintance of mine) and student both parachuted to the ground safely albeit with minor injuries.
On examination, the aircraft’s main spar was found to be desiccated, i.e. all the moisture in the resin/rovings composite had gone leaving behind a structure similar in properties to tissue paper.
The AAIB accident investigation report can be found here
http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_500699.pdf
The pilot continued to fly for some years but has now effectively given up the sport.
tgmccoy says: “Cool. Been hit by lighting in an aircraft.”
It isn’t cool when the lady two rows up the aisle starts screaming. Been there, done that.
I’d like to know if the electronics in the car were “fried” as you postulate.
I had a friend get hit by lightning in his SUV, and there was no damage except a burn mark at the corner of the sheet metal by the passenger front windshield. No electronic problems at all.
Makes you wonder about the EMP disaster scenarios from both manmade and sun-caused events. I know that power lines and EMP are a potentially huge problem, but cars and consumer electronics, I’m not so sure.
My house got hit by lightning. Direct hit on the oil tank vent cap which sticks out of the foundation opposite the basement-mounted oil tank. It blew a few ground fault interruptors, took out my Dish network receiver, one 10-100 ethernet switch, and one of three HDMI ports on my LCD TV.
That’s it, from a direct strike, so again, I’m not too worried about EMP or solar events.
Years ago, houses and other buildings generally had lightning rods. There are fewer lightning rods now. Perhaps that didn’t matter when there was a cast iron sewer vent sticking up and cast iron pipe to the ground, but plumbing is now plastic, and house wiring is too flimsy to deal with lightening. Should houses be equipped with lightning rods? Or were lightening rods less common in the past than I presume and lightning strikes on houses are too uncommon for lightning rods to be worthwhile?
Kids, don’t try this at home.
Heck, some of the other videos are even better!
It certainly is not always the high points that are struck. Way back in days when we were experiencing many vivid lightning storms I lived in an 18-storey apartment building. Far below us, directly across the road was a 3-storey hotel, and next to that a 10-storey YMCA. Those nights I was getting many good lightning shots, and was taking out my camera and tripod one night as a storm rumbled up. As I walked out onto the balcony, a dazzling strike barreled down right in front of my eyes, striking the hotel so very many floors further down. A wind had come up with the storm, blowing some curtains out of an open window. The flash ignited the curtains, which resulted in a huge chorus of shouts of ‘fire’ from the YMCA.
The brake lights continued to work after the strike.
The upward streamer from the ground will have come from the two street lights that the car past under as the lightening struck, the suv will have completed the circuit, you can make out the flash of the streamers from the street lights in the video if you look closely.
@ John Pickens says:
September 27, 2012 at 8:40 am
Makes you wonder about the EMP disaster scenarios from both manmade and sun-caused events. I know that power lines and EMP are a potentially huge problem, but cars and consumer electronics, I’m not so sure.
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I used to have a wrist watch that would reset itself whenever there was a big solar flare. It got to where I would notice it had reset itself again, then go look at the spaceweather.com page for solar flares, and – sure enough – there was a solar flare at about the time it had reset.
Look at the frame at 0:25 two stereamers can clearly be seen arcing from the streat lights just befor the strike! 🙂
I have had several lightening experiences.
My father, my brother, and I were on the front porch watching a thunder storm when lightning hit a telephone pole about 100 feet away. It blew off the top of the pole which landed in our front yard about 20 feet away.
Another time, I was driving down the south loop in Houston. Lightning hit a pole to my right. Shortly after that, lightning hit the corner of a building to my left. Shortly after that, it hit another pole to my left. It was like nature was shooting at me.
Another time, I was working at my computer. In the room I also had my 2 meter radio in the room (N5DXI). The antenna was on the roof. A lightning strike came though the coax into the room with me. The radio was toast but the computer survived. The UPS probably helped a lot. Most of my equipment was connected to that. Also the antenna wire ran next to a cast iron vent pipe in the wall. The flash that I saw seemed to some from where the vent pipe and the coax were next to each other. That part of the wall was open from when the coax was fished down.
Lightning… 🙂
I have never been in a direct strike, but I have been within 500 feet of a strike twice. I was a child the first time, when lightning struck a tree NE of our house. Everyone was sitting in a screened porch when it happened. I felt the hair stand up and a tingling sensation then light/boom! The second time I was grilling in the patio (not screened). Lightning struck a radio tower one block south of me. The tower was the radio-telephone tower used to page personnel and communicate with EMA. No sensation, just light/boom!
Article: “A Faraday cage or Faraday shield is an enclosure formed by conducting material or …”
Here we go again; a Faraday cage works to shield the electrostatic field (E-field) only. It has nil (negligible) effect on the magnetic (H-field) component.
The thing that REALLY protects one inside a conductive cage like a car to a dynamic (changing) signal phenomenon like a lightning stroke is the WGBCO Effect (Wave Guide Beyond Cut-Off) … the same effect that ‘kills’ reception (the signal received) on a portable AM broadcast radio when it is taken inside a car; the wavelength of AM broadcast (and the majority of the lightning strike energy) is way, way WAY longer than the distance/aperture represented by the ‘entry’ points (e.g. windows, doors) into the vehicle … the WGBCO effect forces current to flow on the *exterior* of the vehicle (or conductor or conductive box).
EMI remediation (radiated emissions) relies on this WGBCO effect; the lesson is to keep your slits or holes in your product ‘small’ compared to the wavelength of your problematic EMI/RFI producer situated inside the box.
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Look at the frame at 0:25 two streamers can clearly be seen arcing from the street lights just before the strike! 🙂
…But with respect to electronic components?
I noticed the car’s taillights and brake lights continue to function after the strike.
Biggest lightening strike I ever saw hit the railroad tracks about a mile ahead of me. Turned out a friend of mine’s car was hit as he was crossing the tracks. He was fine. Older model car didn’t even stop working.
I watched this video closely earlier, several times as a matter of fact, and I’m going to submit that it was an object (light pole or other object) JUST beyond the SUV.
Note: The tires do not seem to be flattened and there are documented cases where a car struck by lighting suffered deflation of all four tires, and the pavement was ‘marked’ where the four tires had been as well.
Also note the ‘struck’ vehicle is slowing down for other traffic ahead of it in the same (left) lane. A car is visible in the last frame or two of that video. One will have to run the vid several times or stop it and move around ‘manually’ to see it.
Haven’t had time to digest completely the following report linked below, but, there is a table titled: “Summary of type and number of vehicle related events, deaths, and injuries. ..” in this document and it seems to show 4 deaths and 77 injuries for people occupying a vehicle during a lightning strike:
“LIGHTNING-CAUSED DEATHS AND INJURIES IN THE VICINITY OF VEHICLES”
http://www.lightningsafety.com/nlsi_pls/lightning-caused-deaths-around-vehicles.pdf
Tables contain various accounts/data including the following:
30 June 2000 Wakefield, Rhode Island
“16-year-old girl passenger struck in left arm by current after flash hit
ground next to car and bounced into it; she was taken to a hospital.”
16 July 2000 Chippewa Falls, Wisconsin
“Man injured when lightning hit his car while waiting at intersection; his
arm was numb from current traveling through steering wheel.”
19 August 2000 Cumberland, N. Carolina
“23-year old man knocked unconscious when lightning hit his truck
while driving on N.C. 24.”
28 June 2001 Carmel, New York
“Man and woman driving on Route 301 when SUV was hit in antenna;
paint burned, filled with smoke, windshield cracked, two tires exploded,
and airbags deployed. The highway was damaged.”
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I was once in an airliner (about 120 passenger capacity), when its wing was struck by lightning. Plane shook, it went into brief dive, maybe 2-3 sec but it felt much longer. We were informed that it was a wing strike, on lending we could clearly see that one aluminium tile was damaged, and few more blackened.
Can we expect the number of cars hit by lightning to increase as the rate of global warming accelerates?
beng said:
“Rarely I’ve been very close to a lightning strike. It’s usually proceeded by a slight flash & snapping sound, then a fraction of a second later, the real bolt. Ear-drums can be busted…”
That is a very good description of being within a few hundred meters of a strong ground strike. In a former life, I spent a lot of time at mountain and hill top repeater sites doing communications work for a mining engineering company. I have experienced a good many of these events.
What happens is this:
Lightning strikes nearby. At the speed of light both the light and the spreading magnetic field from the bolt leave the plasma tube and radiate outward. The sonic energy from the heated air leaves at the same time but is traveling much slower (1100 ft/sec)
Then, if you are close enough for the magnetic field strength to affect your nervous system and far enough away that you can perceive the time difference between the magnetic effects and the sonic effects, you “hear” a click (sounds like two steel balls striking one another) when the magnetic field disturbs your audio nerves. Depending on the nature of the strike, you may hear one single click or several clicks in rapid succession. The clicks are followed immediately by the boom of the sonic energy some perceivable number of milliseconds later. The click and the light from the plasma are perceived simultaneously.
This effect does not happen once the strike is far enough away from you that the nerve disturbance threshold is not crossed by the magnitude of the magnetic pulse when it reaches you.
“Watch a severe storm front approach and witness a extremely close lightning strike of a large tree.”
Bill Parsons says:
September 27, 2012 at 9:36 am
“…But with respect to electronic components?”
Car electronics have lightning protection built in (very fast Zener diodes or thyristors or something like that).
I was going up the Malacca Strait once in heavy rain, loaded with motor spirit (gas to N. Americans) and with St. Elmo’s Fire apparent in the mast shrouds, when lightning hit the sea surface about 50 yards away.
Scary, considering that the cargo tanks were venting vapour all the time.
This happened to Apollo 12 shortly after launch. To bad cars don’t have an SCE to aux switch.
Serving at a US Army radio transmitting station (WTA}, near Manila,
P.I. , circa 1948, we had many exciting times with lightning. Located
at a former golf course, the station had about 12 or 14 rhombic antennas.
These elongated diamond-shaped antennas are made of wire stretched
on towers. Some were 700-to 800 feet long The antennas were connected to the station building by open-wire lines on wood poles. The station ceiling was crossed from two sides by wire lines that were down-connected to the transmitters.
A fine collector of lightning that is hard to beat. My introduction to
the events began one afternoon when I heard a series of loud snaps.
With one of the other technicians pointing to the top of a transmitter,
I saw a spark jump from a transmission line to a grounded wire about
a 1/4 inch from the line. He said “Storm near ” , walked to the open
door and pointed to the horizon. About 5 to 10 miles away were large
dark clouds with many lightning strikes. At most strikes a snap was
heard at one of the spark-gaps. The transmitter spark-gaps were not
the only ones, as gaps were also placed the antenna connections
and at the building wall insulator bowls where the lines came through.
That first storm passed us by, nothing more happened.
Another day a storm passed right over us and we took several direct hitson the antennas. The spark-gaps were busy and handled the strikes except one . That one produced a ball of fire that traveled across the ceiling on the wire lines and also down to a transmitter . The noise was
deafening. All the transmitters went off-line due to the strike, and we had to restart them, all except the one hit directly. Later we found that transmitter’s antenna tuning capacitor had partially melted and several
plates fused together. Some file work restored it to service.
So work on transmitters and lines and antennas was always done with an eye on the weather. Also every transmitter had two ground cables that were hooked on to the antenna connection while working on a transmitter. This was done even in the dry season as the transmitter room was rf hot. All conductors had some rf voltage on them . RF burns
are not nice.
I worked at a number of other radio stations around the world but none
had lightning like that at Manila.
rb
I suspect that our newer electronic drive-by-wire and fly-by-wire transportation is vulnerable to abnormal electrical signals, such as from lightning or other transient(?) EMF anomalies.
I personally believe the cars that have the well-publicized accelerator problems have been hit with EMF signals that are just close enough to their actual operating signals that they cause the unintended acceleration. Since it is possible to program one’s iPhone to control a car remotely, why would it not also be possible for a rogue signal to cause unintended behavior in a car or plane that uses drive-by-wire or fly-by-wire control?
I also saw a story recently where a person was getting bogus signals from their car’s tire-inflation system, telling them a tire was low. Upon inspection, it was normal. The problem happened more than once, usually at the same location in a route the person drove every day. I suspect the location that had the trigger was where a strong(?), compatible signal was being emitted all the time.
“””””…..mwhite says:
September 27, 2012 at 7:53 am
I wonder [how] a car with a fibreglass or carbon fibre body would cope?…..”””””
Carbon fiber is a perfectly good conductor in those kind of fields. Fiberglass, not so good. If the lightning can jump 10,000 ft from the cloud, it isn’t going to even notice a few inches of rubber near the ground; it will just jump right from car body to ground; so steel belt or not makes no difference. For that matter, car tires are full of carbon anyway.
Carbon fiber or even fiberglass fly rods, make excellent Lightning rods; I’ve been stung by discharges through a rod several times, in the Florida Keys, sure made me lower the rod tip fast, before the boat got blasted.
Re: vukcevic says: September 27, 2012 at 9:45 am
Forgot to mention that at the time plain was above the clouds (I would think safer) and the strike was under the wing tip. It makes me think perhaps it would be safest to fly through the cloud, in which case plane would not have surface charge different to the one of the surrounding cloud.
Any comments from pilots?
Doesn’t lightning always just follow the path of least resistance? That is, irregardless of the height of surrounding structures.
I have always told the kids…. just remember also that sharp edges and points, especially metal like umbrellas, connected to the ground in any manner, even by just a solid coat of non-pure water, tend to bleed towards the clouds as invisible streamers of ions and this just may help make YOU the path of least resistance!
Bet that SUV had a sharp antenna on top and after all, it was metal and thoroughly wet.
Power Grab says:
September 27, 2012 at 10:26 am
“I also saw a story recently where a person was getting bogus signals from their car’s tire-inflation system, telling them a tire was low. Upon inspection, it was normal. The problem happened more than once, usually at the same location in a route the person drove every day. I suspect the location that had the trigger was where a strong(?), compatible signal was being emitted all the time.”
Other possible explanation: The multi purpose car computer (the one that does audio, GPS, entertainment etc) is also responsible for the tire sensors (as that is probably an informational application, not a safety critical one). Sometimes the navigation software has bad spots in a map that can trip up a software process. A watchdog process will then usually kill that process and restart it, if not the entire computer system. That’s guesswork, but during such a malfunction it could be possible that an error cascade confuses the part of the software that checks the tire sensors.
The funny thing about this kind of error is that it drives the affected person nuts but the test department never caught it because they never drove over that road.
“””””…..DirkH says:
September 27, 2012 at 10:11 am
Bill Parsons says:
September 27, 2012 at 9:36 am
“…But with respect to electronic components?”
Car electronics have lightning protection built in (very fast Zener diodes or thyristors or something like that)……”””””
Well anyone who designs ICs knows that every single “pin” that makes a connection from the outside world to the chip inside, does so through a “pad” that is an ESD protection system, for that circuit. Standard pad designs are capable of protecting against high Voltage discharges for circuits inside the chip.
Pad designs are customised for Input pins, output pins, and power supply pins. Inputs are specially troublesome, because there often is a circuit function need for that input to have a very low capacitance to ground or any other circuit, so having to add a load of crap on there to protect the input against ESD is a nightmare for designers, specially Analog circuit designers.
I once designed an Analog CMOS IC that had only three pins; ground, power, and output. There was no input pin because the chip was an integrated photo-diode detector, and current feedback amplifier, so the input was optical, so no need to bring the amplifier input connection off the chip.
As a resut the input stray capacitance was extremely small, which enabled a very high gain bandwidth product.
There’s no excuse for car or aircraft electronics blowing up from lightning strikes.
Airplanes formerly were protected from the effects of lightning strikes by copper wire wound around and around the fuselage. The technology is evolving, but the same idea of creating a “super” Faraday cage applies:
http://www.dexmet.com/Aircraft-Lightning-Strike-Protection.html
On the sub-thread of flying through electric storms:
My wife and I flew into Austin for a wedding about ten years ago. We traveled through the most intense thunderstorm I hope I ever see up close: constant lightning flashes, several elevator-shaft plunges when encountering sheer. The hail was so thick that the plane sounded like a giant metal scooper being sent through crushed ice at 300 mph.
My experience is that airplane pilots like to underplay such adventures. Our captain that night, as we taxied to the gate in Austin, said this: “I’m not going to lie to you folks. That was one hell of a ride.”
Lightning can be good for cars:
http://tesladownunder.com/Tesladownunder%20Car%20Theft%20Protection%201000.jpg
What are the dangers in a convertible (top up) It’s just a frame with fabric over it.
Broadband EMI susceptibility-testing by the automakers weeds out all but perhaps the ‘keying’ of a 5 watt hand-held transceiver (HT or walkie-talkie) right next to the engine-control computers; the ham community discussion ‘reflectors’ also discuss this, because, some operators run 500 to 1,000 Watts output from amplifiers and they *do* on occasion see strange indications on the dash, but none have reported ‘instantaneous, uncommanded acceleration’ to my knowledge (one tends to remember such events and #2 for such an event word spreads like wildfire thru the ham community …)
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TomRude says:
September 27, 2012 at 8:22 am
OT: The Wikipedia page of Marcel Leroux is under attack by some zealots.
http://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Marcel_Leroux
To those here who have read his work, help would be appreciated.
Thanks Tom for posting that. Actually it is Leroux’s Global Warming skepticism that is the reason why he should be deleted from Wikipedia:
They say they want to clean out bad articles here:
http://meta.wikimedia.org/wiki/Association_of_Wikipedians_Who_Dislike_Making_Broad_Judgments_About_the_Worthiness_of_a_General_Category_of_Article,_and_Who_Are_in_Favor_of_the_Deletion_of_Some_Particularly_Bad_Articles,_but_That_Doesn%27t_Mean_They_Are_Deletionists
Why is the article about Marcel Leroux bad? Because of his “fringe theories” !:
http://en.wikipedia.org/wiki/Wikipedia:Fringe_theories/Noticeboard
“Non-notable scientist that seems only to have an article because peopl like his fringe views on climate — Preceding unsigned comment added by xxx (talk • contribs)
Looks like warmista-zealot with an agenda to me.
My clothesline was hit by a lightening strike some years ago now. It hit near the metal joiner/tightener was located. I did not see it but I heard it, because I had my windows open at the time. The whole house shook with the intensity of the sound after it hit. Where my clothesline is placed is just a foot and half away from my back door. The poles holding the clothesline is wood, so we didn’t have any fires except for charring, and cracking on the plastic coating of the line itself. Some of the braided wire also separated where the coating disappeared, but it was still up and still usable afterwards.
It was one of my neighbours tell me it hit the line, they thought it was an electric line, but it was just a clothesline, as most of our power and phone lines are buried here in this neighbourhood. So it was luck that it hit the clothesline and not the house. (It is still up, but will soon be changed because winters here are not kind to old clotheslines.)
Ummm … no. It begins as a chaotic process involving gas molecules in a strong static electric field, with free electrons stripped from some gas molecules which begin to impinge on other gas molecules and at some point an ‘avalanche’ effect takes over eventually resulting in a ‘plasma path’ through which the bulk of the electron ‘charge’ is transferred.
The determination of the exact path being dependent on many, many local factors including cosmic rays (they assist in creating free electrons) dust/particulates present … by and large it is the local ionization of successive air ‘parcels’ locally as the stepped leader of about 50 meters in length each that determines the ‘path’ taken.
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(Reference: Martin A Uman and his book “Lightning”)
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In an odd way that video has the same ‘script’ as the other Russian car videos on the web. Search youtube for “Russian Driver” and you’ll see.
The usual pattern is like this: Everyone is casually zooming along bumper-to-bumper at 80 MPH on a surface of glare ice. Suddenly a car flashes into the scene from an impossible angle at 120 MPH, very much like a stroke of lightning. A dozen cars spin around in a blender for a few seconds. The cars that didn’t get blended continue to proceed casually at 80 MPH.
While a car body seems to provide some lightening protection it is a long ways from being a Faraday cage, if it were a Faraday cage your cell phone would not get any reception while inside the car.
I watched some great lightning in Kuala Lumpur striking the Petronas towers. I guess they were built with a metal cladding to act as a big lightning conductor, but they were taking a real pasting with 3-4 strikes a minute.
I was in a swimming pool in a nearby hotel and I remember wondering it I was safer in the pool or out of it – does anyone have any thoughts on whether staying in a pool (where you are nice and flat) is better than getting out in a thunder-storm?
@Retired Engineer: Airplanes get struck by lightning on the ground and in-flight, damage is rare.
Depends on the planes. Commercial airliners, not so much. But I’ve seen the result of strikes on several of our 1900s and it’s never pretty- radomes with holes blown in them and the weather radar fried, static wicks blown off, and navcom antennas split open or missing completely.
Another interesting feature of lightning that is rarely mentioned is the X-ray and gamma flash that is produced. The flash can produce a latchup condition is poorly designed CMOS IC’s. It can also upset bits in poorly constructed memories that rely on a stored charge in a gate. The good thing is that the radiation drops of at 1/R*2.
The semiconductors used in aircraft and satellites are S class, which means they have been tested for ESD/latchup and have also been tested for radiation hardness, among the many tests.
We have a lot to thank Faraday for.
FYI… Commercial and military avionics lightning protection is covered by what is call DO-160 specifications, this was derived from a SAE specification and SAE is automative.
I have seen the results of indirect lightning (near field) strikes on industrial and consumer electronic devices. It’s not a pretty sight… burnt it’s cooking and soot it’s done.
Nothing is left but a pile of ash (carbon). Hardened electronic devices can withstand to a cretin degree some near field surges, but taking a direct hit, all that can be done is direct the lightning to ground and pray it doesn’t take anything with it.
I watched one storm from a truck on the Oregon coast many years back. Lightning strikes hitting power poles, trees, the ground. The thing that impressed me the most was watching a bolt hit the top of a house, bounce off, hit a barbed wire fence, run the fence and finally blow up a pump house! I stayed in my truck!
Earlier this year, ballplayers and umps were scattered by a huge thunderclap following a strong lightning strike outside the Texas Rangers’ stadium in Arlington on 7/18/2012:
http://texas.rangers.mlb.com/video/play.jsp?content_id=22970091&c_id=tex
I’ve had several close calls (c100-200 meters) while caught outdoors in the open, and I can understand the reactions of the ballplayers. The sound was overpowering, the ground seemed to jump beneath my feet as if slammed by Odin’s hammer, and my hair was standing on end. Rrrrip flash bang!
While flying over Honshu in a “Scare America” DC-4 back in the 60s, our plane was hit by lightning. I was dozing at the time, but my recollection is that the cabin lights went out briefly, and the pilots had to restart the engines. Dark and silent is an uncomfortable set of sensations in a passenger aircraft, but the entire sequence occurred within about 10 seconds, so the fear came after the event was over. Later, the stews informed us that the bolt went in one wingtip and out the other.
vukcevic says: September 27, 2012 at 10:35 am
Forgot to mention that at the time plain was above the clouds (I would think safer) and the strike was under the wing tip. It makes me think perhaps it would be safest to fly through the cloud, in which case plane would not have surface charge different to the one of the surrounding cloud.
Any comments from pilots?
Most all of my strikes have been inside clouds, big or little airplanes. There’s always been some sort of damage, little pinholes, melted spots, etc. Never had the electronics go out.
I think what some are referring to as “streamers from the light poles” is the refractive edge of two raindrops that hit the windshield at exactly the instant before the strike.
What was most curious to me about this recorded lightning strike was the color of the lightning strike. Most lightning strikes are bright white to blue to deep purple, – ie favoring the ultraviolet end of the spectrum, because of the extremely energy intensive plasma in which the lightning’s current is traveling. Air, made up of 70% nitrogen and water (ie. its raining) usually produce deep purple to blue plasma arcs (see for instance the simultated lightning in the Top Gear video posted by Jud.) In this video the lightning appears red. Either the video camera doesn’t adequately capture the actual spectrum (most likely), or the lightning in this case lit up a higher than normal concentration of Neon, Helium or dust particles coming down with the rain containing metals or metal salts like lithium carbonate, strontium carbonate or calcium chloride.
The only close call I had was on the campus at Sacramento State in the ’70s. Crossing the library quad during what, up to that time had just been a heavy rain storm, I felt everything start to prickle, had time to wonder, “wha…” when there was a flash and a simultaneous boom so loud that my ears rang for the better part of an hour. Never did discover just where the actual strike was. I suspect the Engineering Building which was next to me.
I was at Ranger stadium earlier this year when the strike occurred. It hit across the street at Six Flags, which puts the stadium some 200-300 yards away. The sound reverberated quite well inside the stadium. It was quite jarring.
We quickly evacuated to the ramp area.
“a person’s odds of being struck by lightning are around 1 in 775,000 at any given time”: what on earth does that mean?
I first heard the term “Faraday cage” a few months ago when I rented “The Darkest Hour”.
http://www.imdb.com/title/tt1093357/
I should have waited for WUWT to bring it up. 🙂
“a person’s odds of being struck by lightning are around 1 in 775,000 at any given time: what on earth does that mean?
In law, the term “a given time” refers to a calendar date, unless stated otherwise. The statement would mean a probability of 1/775,000 of being struck by lightning on any particular day.
Growing up in Phoenix, I’ve seen a lot of lighting strikes hitting a lot of things including my neighbors Honda. The camera that took this video was unable to capture the true magnificence of the event. BTW, most of the electronics probably survived.
BTW, I work in a Faraday Cage within another Faraday Cage with an “Air Lock” for a door.
Glad you have reported on the Faraday cage and the “skin effect”. Too many people come to Florida to play golf and assume that the rubber tires of a fiberglass golf cart will protect them from lightning. Now, how many of you have seen lightning come out of clear skies in front of a moving storm? That is another way visitors to Florida get hit by lightning. Rule of Survival: if you hear thunder, it is time to take shelter.
It’s something of a myth that lightning strikes tall objects.
Twice is Singapore I saw lightning strike the ground next to tall buildings. Once within 5 meters of a 4 storey building and the other time about 10 meters from a 20 storey building.
While Singapore has a high rate of lightning strikes, the death rate per million population is half that of the USA. (0.35 vs 0.6). I assume because in an urban environment you are less likely to be outdoors in a thunder storm.
I remember having a bolt strike a tree ~400 yards from my house. Shattered the Yellow Poplar it hit (formerly emergent canopy position) throwing splinters over 200 yards. Difference in step potential between the House ground and the ground on the Cable line sent a surge that fried 2 DVD players, Cable modem, and network card. Strangest was the frying of a firewire card and drive cage from induced voltage (firewire cable ran parallel to the Co-ax). Loud boom followed by the smell of burning plastic, not fun.
carrying a senior Russian official on a rainy Russian day
It was the vodka. Its not called white lightning for nothing.
Driving in Arkansas on I-30 going North just past Texarkana when simultaneous flash bang of lightning strike. Spot on right rear door top top of ’85 Astro Van looked like a BB had hit it. Killed the cruise control, but did no other damage. Was kinda scary though.
Back in 1975, I was working for Green Giant Co. Ripon WI, as a field mechanic during peas, beans, and sweet corn harvesting seasons. We had a hard rain fall one day, that made harvesting impossible as the equipment was constantly getting stuck in the mud. The pea combine drivers were sent home, the foreman left the field, and I stayed behind to finish repairing a broken combine. There was a small bit of lightning on the horizon but none within 10 miles of the field site…. no problem!
A light rain was falling as I was stretched out under the broken combine, welding up a cracked frame member. I had a rubber rain coat under me to keep me off the wet ground and another one pulled over me to roll the hot sparks from the welding off of me as they fell. Of course, with a welders face shield over my head much of the time, my attention focused on the weld repair, and a noisy portable welder unit running near by, I wasn’t aware that another squall line was moving into the area.
The repair was progressing fairly well….. until a hickory tree in the fence row about 100 feet away was hit by lightning! The concussion sent me crab scuttling sidewise out from under the combine to see what had blown up! The tree had a steaming strip of barkless trunk about 2 inches wide running into the ground and up to the branches near the top. Bits of steaming bark had been blown out into the field and even the dirt had been blown up off of the root that had carried the the charge ‘to ground’! I could hardly hear my gas engine powered welder running, from the thunder clap after effects on my hearing.
I climbed into my mechanics truck for shelter and, after my hearing had returned to something approaching normal, I called the Green Giant mechanics shop (business band radio, “Truck 304 to Base….”) to tell them I was packing up and heading in to the plant. “Did you get that combine repaired?” I was asked. “No.” I replied. “Why are you coming in before the job is finished?” they queried. “Because I just had a direct order from God telling me it was time to quit!” I replied. “I’ll tell you all about it when I get there…”
Ahhhhh……. the Good Old Days!
Old school rule is for a lighting rod or something that acts as one, the area protected must be under a slope of one foot hight for three feet distance. The other rules still apply such as it’s better to be inside and stay away from trees because they are not true lighting rods.
Our house got hit some years ago. The bolt hit the gable of our bedroom. It blew bricks off the gable. I slept through it.
Firstly, it is called “lightning” – not lighting (illumination); not lightening (make weigh less).
Secondly, lightning is a half-wave at very high frequency – not static electricity. So what you have from a lightning strike on a metal container is high frequency skin effect – NOT a Faraday Cage:
Skin Effect
_Jim:
“Ummm … no. It begins as a chaotic process involving gas molecules in a strong static electric field, with free electrons stripped from some gas molecules which begin to impinge on other gas molecules and at some point an ‘avalanche’ effect takes over eventually resulting in a ‘plasma path’ through which the bulk of the electron ‘charge’ is transferred.”
Basically, isn’t that what I said about the pointed umbrella and ions? I still say that lightning always follows the path of least resistance, cloud to ground or vice versa, and you are correct that ion streamers, “plasma paths”, caused by the local electric field strength are what weaken the resistance making that path the least one (but usually multi-branched and rarely a straight one). Also, there are usually even much smaller and weaker sub paths dissipating the change differences.
mwhite says: “I wonder [how] a car with a fibreglass or carbon fibre body would cope?”
Fiberglass might have trouble because it is an insulator.
However, carbon fiber is a conductor and should perform well. There even supposed to be some TEMPEST type products that use it to create EM shielding (faraday cage).
As long as we’re telling stories.
Weather permitting I always watch thunderstorms outside.
Once had lightning hit REALLY close, I instantly smelled burning hair.
It wasn’t mine, I checked.
??
Question for those knowledgeable. Will wrapping a grounded mast or vertical exposed metal pipe with barbed wire reduce the likelihood of a lightning strike?
eyesonu, more likely it would seems. Wasn’t it Franklin who discovered that sharp points on lightning rods were much better than smooth surfaces in drawing the lightning to itself?
Speaking of masts, I had a pretty large sailboat for over twenty years and never had a problem with lightning, but I guess that because the twenty-five foot mast was not stepped on the lead ballast but on the upper deck giving about a four foot gap that was merely a large dry timber within the cabin. But in stormy weather, and I did a lot of that running under storm jib only, I always made sure not to list too much, putting one of the stays down and very close to the water for that very reason.
I suppose on the open ocean or great lakes without trees nearby on the shore you would probably be a much greater target for a lightning hit. That ‘path of least resistance’ rule has never let me down to date. ☺
Man, you got that right. They are the world’s foremost exporter of incredible traffic accident videos!
Fully agree. But YouTube is way too tame and stuff just disappears. IMHO a much better site is LiveLeak.
They have too many dashcam recorded fatal car accidents in Russia to count. Example. Here is a nasty video of the aftermath of one of these crashes. Show these to your teenagers, you’ll be doing them a favor.
They have lots of Lightning Strikes too. Example.
And then there is the related category of Electrocution which also serve as a public service announcement to remind us of what happens with a very small fraction of the current of a lightning strike. Example. Here is Another.
Well Lightning strikes are a static electricity phenomenon; well; until it decides to zap you.
So whether it is a go or no go, is a question of static electric fields.
And I’m flabbergasted that nobody here seems to know the key parameters. The electric field near a charged wire is inversely proportional to the local radius of curvature of the wire, or 1/r^2 for three dimensional curvature so that is why it is sharply pointed objects that promote a breakdown of the air. Obviously nobdy seems to have smashed their plasma T&V screen yet. The plasma cells inside that display, use field emission electron sources. There are sharp points inside each pixel to create an electron beam under high electric fields.
So the usual advice if caught out in the open, in an electric storm, is to make yourself look like a “hemispherical boss on an infinite plan”e, so you should get down on the ground in the fetal position and make your self look as round as you can. Don’t worry, at those sort of electric fields, the lightning sees you as a perfect conductor.
Another example of the phenomenon is the Geiger counter, which consists of a very fine usually Tungsten wire in the center of a metallized glas cylinder. A high Voltage is applied between the wire and the surface metallization, so it sets up an electric field that increases in strength the closer it is to the wire. When an ionizing particle strikes a gas atom in the cyclinder (low pressure) it ionizes the gas, and electrons are swept towards the wire, with the ions then drifting towards the glass. If the Voltage is high enough the electrons accelerate enough to ionize another atom or molecule, so that the current can be greater than just the number of electrons released in the original ionization event. In this range, it is usually called a proportional counter, and the total charge released is proportional to the energy of the ionizing particle, so it is using positive feedback to create a charge gain.
At higher Voltages still, the electrons gain energy so fast, that they create a veritable avalanche of charge, and the ionisation starts right at the tube wall. In this mode, the thing is totally non-linear, and the same total chage is released from the very first ionisation event, no matter what the energy. This is the Geiger region, and the pulses are now saturated and independent of ionising radiation energy. Such tubes can also detect non charged particles like neutrons and gamma rays. The incoming neutron strikes an atom and kicks out a proton from the nucleus. This “knock on” proton then starts the accelerated charge ionisation process. In the case of gamma rays (high energy photons), it is an electron that is kicked out of the atom. Proportional counter tubes designed for neutron detection usually contain carboniferous gases and materials, because carbon is a good source of knock on protons . Even so, proportional gas counters for neutrons are quite inefficient, and maybe only count one in 10^4 neutrons, but they can be made totally insensitive to gamma radiation. Modern scintillation crytals and materials like Anthracene and Stilbene are much better neutron detectors.
Bt it is that 1/r electric field or 1/r^2 for spherical points that promotes the discharge. I believe there are some quite recent papers, that show the lightning rod process is somewhat more complicated than just the sharp point business.
But once the zap gets going it will go where it damn well pleases
Having been hit once by lightning all I recall is the biggest camera flash imaginable going off in my face and being thrown backwards about 3 meters. Other wise no injuries apart from a few bruises and singes. I was out in the open, but never sure as to why I was not more seriously injured.
TomRude says: September 27, 2012 at 8:22 am
OT: The Wikipedia page of Marcel Leroux is under attack by some zealots.
http://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Marcel_Leroux
To those here who have read his work, help would be appreciated.
Done. Like I did (thanks to someone else’s find of the article on the Wayback Machine) for Tim Ball, an even more scandalous deletion by WhackaPedia.
This page has a world map of lightning frequency distribution.
Russia seems far less likely to receive lightning strikes than the US.
There are a lot of good YouTubes on lightning strikes, I’d say many are more interesting than the above.
I took out single frames from one of these, in order to observe how the path, narrow at first, is widened during the strike in order to let the electric plasma through more efficiently.
I was a commerical pilot for 35 years and and have been struck by lighting only once. The plane was a DC-9 and the strike burst the navigation lights on the right wing and made several pinholes in the wing tip. No other signs of the strike . The thunder clap was very loud. Many times in other cases static electricity grew so strong on the a/c you could see spikes moving back and forth from the nose of the plane. Sometimes this charge would jump off on a cloud and cause what appeared to be a lighting strike along with a loud clap of thunder. This seems to be the cause of lots of “lighting strikes” and it is really static build-up. You can stop the build up sometimes by slowing down or turning , but sometimes in daylight you don’t see the build-up before the discharge.
The driver thought he had hit a typical Russian pot hole 😉
You should check the “we love Russia” compilations on Youtube for crazy Russian stuff!
Some one mentioned that an aircraft is also a good faraday cage, that can depend on your definition of good. In a 727 as a flight engineer out of darwin, a rather tropical place we faced thunderstorms to 70,000ft with with no gaps. We were climbing and descending at 10,000ft per minute without doing anything when the lightning started.
Then it got interesting, it fried and blew off or up every aerial on the aircraft and took out the electrical system. Thus we had a boy scout compass on the combing panel and a battery that powered enough instruments to tell us which way was up for twenty minutes. So far a lot of fun then the saint Elmo’s fires crept all over the cockpit.
That was special, could hardly see the instruments and everyones hair was standing on end, that was the fun part, the turbulence was so rapid that we suffered eye ball bounce whereby your eyes can not keep up with the movement, blurred vision and creepy green fire was a tad surreal.
We were continually struck by lightning maybe five hundred times by the burn marks later counted.
The problem of no generating power was the foremost problem, Boeing in their wisdom made the system such that the fault that shut down the generators could only be reset by turning off the battery and thus not knowing which way was up. That was a gamble, not knowing if it would turn back on again, that was a small problem, the blurred vision and the hands going up and down trying to manipulate switches and circuit breakers was a real challenge.
We survived and arrived with one generator and two fried ones and an aircraft with almost nothing working, lightning is not very friendly. Willis’s thunder storms to get rid of the heat are a reality.
I have several lightning related stories I will tell my most memorable. A friend invited me sailing one evening in Tampa Bay. A typical afternoon thunderstorm rolled through with strong gusts of wind and occasional lightning. We furled the sails set the anchor and asked the ladies to go below.
The anchor pulled and we were struggling to keep from being driven ashore when when suddenly we were in the most spectacular lightning storm I have ever experienced. Bolts were snapping at a rate of one per second! It seemed to last for a hour but I am certain it was less than 5 minutes. It lasted long enough for both my friend and I to see the big aluminum mast with suspicion and to our horror discover the fuel tank for the kicker motor under the boom with lines inches from it. After moving the fuel tank as far from the boom as possible we waited for the storm to pass while fighting our continued drift with the dragging anchor and the kicker motor.
Nothing more than extreme apprehension occurred and a memory of hundreds of snap boom lightning strikes at a rate I would have considered impossible.
@Paul Jackson
>…if it were a Faraday cage your cell phone would not get any reception while inside the car.
Unless, as explained above, the openings in the cage are larger than about 1/4 of a wavelength in which case the signel passes right through. A radio wave ‘reflector’ does not have to be a solid object, only have holes smaller than 1/4 of a wavelength such as chicken wire and a TV signal.
That is why a microwave oven has a perforated metal plate behind the glass in the door. It keeps all the microwaves inside because the hole is much smaller than the wavelength of the EM bouncing around inside.
i did. It’s above. You just missed it. And no mention in yours about stepped leaders, and which accounts for the crazy circuitous routes lightning takes sometimes since it is the *stepped leaser* which establishes the path for the return strike and its large and more visible current flow (but to your credit you did mention the avalanche effect). Maybe you are adverse to my shorter blurb rather than a dissertation on the subject?
How does this work for lakes and other flat bodies of nothing but water (I have witnessed this and it was while I was transiting the Lake Texoma dam bridge during a thunderstorm while on field assignment with a cellular carrier)? I ask rhetorically … but the answer lies in the downward-moving leader and the local ‘breakdown’ of successive air parcels (and in different directions each time based on what has been seen during observations) as the stepped leader progresses downward …
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Well, I latched onto your statement “Doesn’t lightning always just follow the path of least resistance?” and actually there is no ‘path’ of least resistance until the stepped leader has finished its work, and since lightning *begins* with that DOWNWARD stepped leader process until that part is over, there isn’t any path even!
Lightning is a little more complicated than most folks visualization of a simple series circuit and the simple application of Ohm’s Law determining ‘paths of least resistance’ and where current will flow; lightning involves high voltage static field, gas molecules, free electrons, an avalanche effect evolving into a “conductive gas plasma” and what has been described as the “4th state of matter” … since each stepped leader segment is about 50 meters in length (see: Uman’s book for the research on this) it is the LAST leader segment that determines what gets hit … and ANYTHING that enhances the BREAKDOWN of the air and subsequent avalanche effect in that last parcel will determine the eventual target of that leader and then become the source of the return stroke … present thinking is that SHARP POINTY OBJECTS on potential *ground* targets *reduces* the possibility of the object with the SHARP POINTY THINGY being the *object* or target of the downward-stepping leader stroke, and THIS CONCEPT runs COUNTER to most people’s thoughts on this subject re: ‘paths of least resistance’ et al, as inspection of comments on this thread seems to show …
I think the category of device you are describing is an “ESE Devices” – for Early Streamer Emission devices … there is a debate currently before certain technical committees regarding manufactures claims, and the legitimacy of those devices and the ‘claimed’ protection radius; they are *not* living up to claims …
This is the Yahoo group on this topic if you are interested:
http://tech.groups.yahoo.com/group/LightningProtection/
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The statement would mean a probability of 1/775,000 of being struck by lightning on any particular day.
with a world population of something over 7 billion, wouldn’t that mean that ~10,000 people get struck by lightning every day? This would seem very high.
or does it mean that there are 10,000 lightning strikes every day, one of which would have to hit you?
or that of the 10,000 daily strikes, one in 775,000 hits a person? meaning one person gets hit every 77 days? This would seem low (with 400-500 reported every year in the US alone).
I suspect that this is 1/775,000 in the US. With a population of 300 million, this would work out to about 400 people per day, which is about right.
math is easy. communication is what’s hard…
and, of course, I communicated that incorrectly…
that would be 1/775,000 in a year, with about 400 strikes per year
Reblogged this on WrAnTz and commented:
Have always known about the Faraday effect for cars but have never heard of a one being struck while being driven. Amazing.
“””””….._Jim says:
September 27, 2012 at 11:37 am
wayne says September 27, 2012 at 10:37 am
Doesn’t lightning always just follow the path of least resistance?
…
Ummm … no. It begins as a chaotic process involving gas molecules in a strong static electric field, with free electrons stripped from some gas molecules which begin to impinge on other gas molecules and at some point an ‘avalanche’ effect takes over eventually resulting in a ‘plasma path’ through which the bulk of the electron ‘charge’ is transferred……””””
The hell you say _Jim; you certainly did !! Dunno how I skipped over that. And what’s more, you covered all the bases in a more concise and cogent statement than I did.. Sorry Mate, I’ll pay more attention.
And further on the static electric field business, some commenters have implied that it is some sort of high frequency RF effect.
Not so; but once the discharge gets going, you do get a gigantic high field EM pulse effect (Transient) and simple signal theory explains that that will generate a broad spectrum of EM waves depending on the length of the pulse, and things like the rise and fall times of the pulse; and of course in the wild random streamer structure, it will be a complex pulse.. It will take something in the 5-20 microseconds range to reach earth, and last somewhat longer than that. In practice, it turns out that the RF spectrum is actually concentrated in the audio range from a few Hertz to a few KHz. A lightning strike at one point on earth will launch an EM wave train that propagates through the ionosphere, guided also by the earth magnetic field, so some time later, and echo will be received on the other side of the earth. This arriving signal, will partially reflect from the partially conducting ground plane, and return via the filed guiding to the original or nearby location. This bouncing back and forth can occur several times.
There are listening stations at strategically located places, that co-operatively record these signals , to generate interleaving signals of the very same lightning strike. As it turns out, the ionospheric transmission path is dispersive, so the different audio frequency waves travel at different speeds and the higher frequencies get there first (usually), which is the same as waves on water. So the signal received at each station is a whistle that starts out high frequency and sweeps to a lower frequency as the slow pokes arrive. So each subsequent transit, is further stretched out so the two listening stations can match their records, and see the beautiful interleaving of chirped signals.
They are actually called “Whistlers ” by those who study these atmospheric EM phenomena. Well there are also Howlers which as I recall chirp up in frequency rather than down, and then there is “dawn chorus” and some other named types.
The DSIR in Wellington NZ used to be one such recording station hooked to another station in Scandinavia somewhere. I spent a summer there in the early 1950s when they were doing that stuff. Well I was doing my Radio-Physics courses at the time.
I was mowing the 10th fairway on a Toro 5100D when lightning struck the roof. For a few seconds prior to the strike I could feel my hair standing on end and the air smelled different. Then a huge flash followed by the biggest bang I ever heard. I could see the flash moving down the window posts and the arms of the mower. My vision afterwards had streaks like when you look at an arc flame or at the sun. The mowing electronics were fried but the diesel engine started right up again and the hydraulics were fine. There were 5 rectangular burnt patches on the turf where the cutting units completed the circuit. No-one believed me until they saw those patches and the couple of scortched and blackened spots on the roof.
I would be remiss if I didn’t include these two references on the subject of ESE Devices (which roughly includes “Franklin Rods’ as well as other devices) regarding the shape and propensity to ‘attract’ or ‘get hit’ more or less often per my address to/discussion above with wayne:
From: http://www.lightningsafety.com/nlsi_lhm/early-streamer-emission.pdf
Titled: “A review of studies on Early Streamer Emission and Charge Transfer System conducted in Malaysia”
I extract this part re: sharp tips vs blunt tips (where they observe that blunt tips get ‘hit’ *more* often than sharp tips – which at first pass sounds counter-intuitive, but that has been the reported observation by researchers):
A similar observation is made in this document on Pg 15, 2nd paragraph, 9th line down:
http://www.nfpa.org/assets/files/PDF/Research/ESE_Air_Terminals_segment_1.pdf
Titled: Early Streamer Emission AIr Terminals Lightning Protection Systems,
Literature Review and techniacl Analysis,
by NFPA
By these observations, then, allowing or enhancing corona discharge, allowing a ‘bleeding off’ of charge locally into the local air parcel at/near ground level, it appears that the voltage difference seen by a descending stepped leader could be reduced such that the strike does _not_ occur to the sharp-tipped Franklin Rod or ESE device, but rather some other unlucky ‘target’ in the vicinity will get zapped as the stepped leader approaches and causes the ‘avalanche’ breakdown toward that target instead … using this technique there would appear to be some degree of ‘protection’ that could be obtained … and therein also lies the claim by ESE Device manufacturers.
Given the nature of lightning though, the ESE devices deployed in real-world situations have not always ‘warded off’ lightning strikes as intended, but it appears to me that in these situations nobody provided any ‘targets’ for the impending lightning bolt to strike either … the simple deployment of an ESE Device will not ward off an on coming bolt, rather, it looks to me like the deployment of blunted Franklin Rods are what are called for; perhaps manufacturers have found it unwise to advertise (or recommend for installation!!) a device that is warranted to attract lightning?
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My wife and I “read” a verbal biography of Ben Franklin while driving up to the Shenandoah Valley for vacation (All touring and historical, new museums and new monuments every day!). Yeah – We’re nerds. Both engineers. Even have our private research librarian MS/programmer MS/math BS/physics BS as a daughter.
The “sharp point” vs “blunt point” arguments – for and against!! – his lightening rods were vehemently discussed, printed, written, and argued in his day across every continent and in every scientific society of the day.
Best summary:
Yes, lightening rods only protect a limited area – You NEED an well-grounded lightening rod on YOUR house to prevent a lightening bolt from burning YOUR house when lightening strikes YOUR house.
However, your lightening rod will not protect your neighbor’s house, nor the far end of your (big) house nor your nearby barn unless it is very far up above the rest of the area. In that case, your big tall lightening rod WILL attract more lightening than a short unprotected house or unprotected barn without any lightening rod at all.
An ungrounded or poorly grounded lightening rod, or a too-short lightening rod will NOT protect your house as well as it should do if it were properly grounded and attached, and MAY attract stray lightening bolts that would have otherwise gone done someplace else.
Up close – where all easy-to-do demonstrations and laboratory tests and simple experiments tend to be run – a sharp-pointed lightening rod is much, much more effective than Franklin’s opponents in the French legislature and scientific societies’ “rounded end” lightening rods.
However, in the real world where a building is several thousand feet below the clouds and their various static electric charges, the actual little bitty point on a little bitty lightening rod is meaningless. Round or sharp, the thousands of feet of travel for the initial charge can’t “find” the few feet of improved attraction distance that a sharp point rod provides.
Thus, either lightening rod “point” is equally good.
Ummm … are there any cites or references you can provide (like I provided)? Conjecture has its place, but I always like something I can ‘lay’ my eyeballs on …
Note also: I am not about to provide advice, counsel, hints or recommendations on what type, make or model of air terminal, ESE Device or FR (Franklin Rod) for protection of any structure, building, dwelling, barn or abode … the above postings by me, at least, are for DISCUSSION purposes ONLY. My best advice is to consult a PE in your area whose practice is lightning protection, or become informed, learned and practiced and perhaps credentialed (and aware of NEC requirements) yourselves in order to adequately address any and all safety concerns (no one needs to try and ‘engineer’ a lightning rod system ONLY to endanger themselves and family owing to erroneous materials selection or incomplete or unsafe construction of same.)
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This just in (had it parked in a tab in Chrome) – for those who might want to roll their own or read the recommendations of the National Fire Protection Association:
NFPA standard #780, “Standard for the Installation of Lightning Protection Systems”, 2004 Edition
A brief excerpt of the ‘scope’ and ‘purpose’ sections:
1.1 Scope.
1.1.1 This document shall cover traditional lightning protection system installation requirements for
the following:
(1) Ordinary structures
(2) Miscellaneous structures and special occupancies
(3) Heavy-duty stacks
(4) Watercraft
(5) Structures containing flammable vapors, flammable gases, or liquids that give off flammable
vapors
1.2 Purpose.
The purpose of this standard shall be to provide for the safeguarding of persons and property from hazards arising from exposure to lightning.
– – – – – – – – – – – – – – – – – –
This document spells out the size of ‘air terminals’, size of conductors, recommendations where to mount the air terminals on various roof topologies, ‘Zone of Protection’ calculations, etc.
For the entire thing see:
http://uqu.edu.sa/files2/tiny_mce/plugins/filemanager/files/4310333/Appendix_-_NFPA_Standard_780_2004.pdf
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_Jim, now that aspect of actually bleeding off charges by very sharp points does make some real sense but I was speaking of all of these effects included. You can see that effect from various geometries about a Van der Graaf generator or Tesla coil and I’ll stand corrected on a couple of my statements not being so clear. But also keep in mind that if sharp points are in fact locally bleeding the charge differential that does also make that path more resistant so another metallic object at same distance not bleeding charges will then become the path of least resistance. Will you agree to that?
@ Anyone:
Here’s a neat lecture on Faraday cages:
(see the demo near the end of this video)
http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/lecture-5-electrostatic-shielding-faraday-cage/
Here’s another lecture on static charges and electric fields on a non-smooth surface (ie. sharp points):
http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/lecture-6-high-voltage-breakdown-and-lightning/
When I was in Florida as a kid, I remember mom driving in the rain. The other side of the road was dry as could be, while we were getting pounded. At a stop light the car in front of us got hit by lightning. It was the car closest to the light poles. Totally hit the lower lying car and skipped the pole.
Luckily, not hit personally or in a car.
However, our last house was hit and it killed our (vinyl, LP) turntable: the copper on the PSU pcb was evaporated and nicely painted the interior of the plinth. That’s as close as I ever want to be!