…Kevin, enjoyed your lengthy description of Current paths…where and why.
I have so much gold in my mouth - I guess I don’t have to worry about lightning!
Mookie
Just a little fyi:
Lightning does not always “look” for a negative discharge; some lightning IS negatively charged and “looks” for a positive outlet. Negatively charged lightning is not that common in cloud-to-ground discharges, although it is much more frequent in cloud-to-cloud lightning. There are many factors that determine how lightning forms.
And nevermind all those odds quoted above; lightning kills more people each year (on average) than ANY other weather-related event, including tornados, hurricanes, or floods.
Aircraft get strcuk by lightning all the time. Planes themselves build up a healthly static charge while passing through the air, which is discharged through static wicks located at the ends of the control surfaces on the wings and tail. If you’ve ever seen little black tabs that look like long candle wicks, that’s them. At night, in areas on high humidity you can even see them glow sometimes. In the cockpit, going through clouds you frequently experience st elmo’s fire on the windshield, which is just static building up. When lightning strikes a plane, it SHOULD pass through and out the static wicks, along the path of least resistance, however, I have seen it blow wicks off in the process (happens all the time) and occasionally scorch the paint at point of impact and departure. Equipment that is poorly grounded can be damaged and happens from time to time. Radar antennas seem to be particularly prone to this. Also, if you’ve ever watched videos of helicopter rescues (particularly at sea) the rescue swimmer from the helicopter will allow the hoist cable to enter the water and ground before they touch it. Helicopters create intense, sometime fatal amounts of static because of the rotors. Not much point to surviving until the rescue guys get there only to be electrocuted by the rescuer.
As usual, I am getting quite an education!
Jen
Either way… Lightning would msot likely not strike a Train Because:
Let’s say the lighning is postivively charged:
A) the train tracks are positively charged, therfore the magnetic field it emits is Posotive and putting 2 posotives together is like putting to magnets together at points S and S … what happens… they repel each other… so Lightning would NOT, as I previously stated) be attracted to Tracks
Let’s say the lightning is Negatively charged:
The current travellign through a rail… is… i’m not quite sure of the EXACT I/E ( I = Current intensity, AKA amperage, E = Volts) however, opposite poles ARE attracted to each other, but the low voltage travalling through the tracks (I’m assuming it’s a low voltage, if it isn’t, then it’s the LOW amperage) either one of those factors, the LOW E, or the LOW I, cause a very weak Magnetic field, and the lightning would much rather come into contact with A higher, more prodominant, metallic object, such as a powerline (If the lightning Charge is Negative)
Negative lighning charges are rare, You are surrently sitting, on the negative battery if the world was one giant battery, everyhting would be negative… thats why power lines are in the air, or under ground insulated From the ground… Negative lightning Rarely strikes ground because of
(-)(-) the TWO negative charges! rememebr same poles Repel each other.
Now, in as much electrical studies i have done, everyone knows that they have 3 wires comming from the power lines
the black one: 120 V
The red one: 120 V
The bare one: the Standerdized ground (AKA white wire)
note: lots of power companies don’t color code them on the telephone poles black and red, they are mostly black and black.
Between the Black and the ground, or the red and the ground you get 120 Volts.
Between the black and the Red you get 240 Volts, for heating Devices, stoves… blah blah… all major appliances.
It’s not about “magnetic” charges - it’s “static” electricity - electrical potential - voltage differences - between the cloud and ground.
The voltage necessary to generate that huge (3 times hotter than the sun) arc discharge between cloud and ground is hundreds of thousands (or even millions) of volts.
Power lines are indeed struck with some frequency - they are often higher than the surrounding conductors, and regardless of what charge the power company puts on them (which is by the way AC not DC so it’s neither always positive nor always negative) they are close to ground compared to the charge the cloud is unleashing. They have spark-gap lightning arresters which arc over and take the brunt of the strike to ground (so most of it does not end up coming into everyone’s house).
Tracks might as well be ground. Whatever signal-activating voltage is there is low (24 volts or less is my guess - kids don’t get electrocuted shorting tracks together with a length of wire to see the crossing signals go on) and is not relevant to the attractiveness of them as a ground-like target. They have 6" metal spikes driven into the dirty and wet (it’s raining, remember) ties sitting on dirty and wet ballast sitting on ground. It may not exactly be zero ohms from the point of contact on the rail to earth, but the rails conduct and those spikes and ties up and down several hundred yards of the line make a pretty good ground. The lightning struck through a few thousand feet of air so that last few inches of ties and ballast looks pretty good as a conductor by comparison. Put a metal, 16-foot-high, steel-wheeled train on those rails and in open areas it’s a juicy target.
The anecdotes 2 or 3 others have posted here about lightning-struck engines in their shops within the last few months would seem to indicate it happens a bit more frequently than lottery winning. From NASA… "Typically, more than 2,000 thunderstorms are active throughout the world at a given moment, produci
Three times hotter then the sun? Never heard that before evn on the discovery channel!
top line emeits a magnetic field, and whats this Bull about a static electricity, which plays no role, FOR THE RECORD, power lines are the least likely to get struck by lightning
Wow, that is Stupid, see Trains have Axels, and the wheel one one track is connected to the wheel on the other track, if those were opposite charges, we’ed be crap out of luck and be shorting everyhting out every time a train goes over the tracks… Wow, obviously not troubled with the smarts are we?
[quote]
QUOTE:
The anecdotes 2 or 3 others have posted here about lightning-struck engines in their shops within the last few months would seem to indicate it happens a bit more frequently than lottery winning. From NASA… "Typically, more than 2,000 thunderstorms are active throughout the world a
Kevin-
FYI
Regarding the temperature of lightning, the statement about lightning being three times hotter than the sun is a conservative number. The surface of the sun averages about 10,000 degrees Farenheit, whereas the temperature of lightning can reach 50,000 degrees Farenheit, FIVE times hotter than the surface of the sun.
And your derogatory comments directed towards the other posts that you quoted are quite unnecessary and are not welcome. [V]
Come on Kevin, you’ve done some quality posts and comments before, why resort to name calling?
I agree with zardoz and cosmi. I was a welder for 7 years and that short lillte arc (between 200 and 650 amps…mig, submerged arc is even higher in amperage) can be in excess of 10,000 degrees F.
Kev, chill out. I tend to be a little fiery myself, but, when I flame an old head, I usually end up looking like the ***.
Ken
i am by far no expert however i do know, believe it or not lightning strikes 2 ways one of from cloud to cloud the other is from the ground up yeah thats right lightning strikes up not down remember electron flow the earth has a negative charge you must also remember lightning like any other voltage is realative to somehting. static electricity looks for a diffrence of potential thats how it can go from cloud to cloud they may both be positive compared to the earth however one may be negative when compared yo the other, hence the diffrence of potential. i agree train tracks are not the best ground being located on a bed of gravel and the main part touching the ground is the wooden tie however i do know lighting hit the 779 and i dont doubt that it hit the AC 4400 dkemd mentioned i do not know why it strikes where it does i dont know why it struck a 15 foot peach tree in my back yeard instead of a 70 foot oak in my neighbors it is however one of natures most intriguing phenomena ask a golfer. i hear they get struck by lighting 300 times a year or more i wonder how many lighting strikes a pair of golfers pants are good for ?
Wow,
Hey Kev, take a deep breath and chill for a minute.
You know me, sorta, so you know I dont tell lies.
My train was hit, twice within seconds.
Down here on the gulf coast, we see summer thunderstorms almost daily.
We were pulling a track out to switch, and a bolt hit a UP reefer twice, once on the frame that holds the compressor and heat exchanger, and once on the roof.
It tripped the ground relay on the locomotive, and blistered the paint off the roof of the car. The frame had a small piece, about two inches long, that looked like a drunk welder tried to cut it off.
And it was quick, all we heard was a double boom! and the locomotive quit loading.
At first, we though we had busted something in the engine, but when my engineer reset the ground relay, every thing worked fine.
It wasnt until we were shoving back into the yard that the yardmaster told us we had been hit, (he had seen it from the tower) and which car had been hit.
Down here, all the high power line pylons have a additional ground rod attached to them, because their legs sit in huge concrete pileings and do not offer a good ground.
Was watching a program about lightning on the Discovery channel a few weeks back, and part of the program discussed the fact that, occasionaly the earth sends up a small charge they refered to as a leader or feeler charge, as if it was trying to attract a strike.
They captured this on film, it shows up a micro scecond before the strike, reaching upwards like a small ribbon about 4 to 6 feet long.
Without going into a lot of the techno poop, it seem that some clouds create a large magnetic field which makes electrons line up underneath it in some objects. This in turn creates a static charge opposite the charge of the cloud, and as the cloud get closer or lower, the charge flows up any object it can, trying to get to the cloud from ground, creating the feeler or leader.
They captured this several times, coming from trees, the edg
If you watch sometimes, lightning will flash 7-8 times in a row. This means it’s found a good place to ground…
okay it seems i have come under fire with my posts, Rereading the comments of… Csomervi i took one of his statements as a personal attack and got well somewhat angry… or very angry and started name calling, which i should not have done… seen where trhis goes before mine as well make up amenze before i get too many people angry at me.
Life is to short to be angry at people, And to become so angry at A misunderstood coment really brings to light the immaturity still in me, I use no excuse to justify that behavior, nor am i going to pin the blame on a misunderstanding.
And i tell you all who read this, you should all go out AND DESTROY your enemies right now! Abraham Lincoln, Once said, “I destroy my enemies by making them my friends.” That is the only way to Destroy your Enemy.
on that note, i offer my apologies too… CsomeRVI… i am sorry for misunderstanding you, and taking your coments in a completely opposite way for which they were originally intended.
By the way, Kev,
One of the ways you can tell who a real gentleman is when he is man enough to reconize he has made a mistake, and how he goes about rectifing the mistake.
Good job, Sir.
Ed
Hey, Kev - no problem.
I was just trying to clarify some of the involved phenomena - those two web sites I gave links for pretty much describe it.
As for signals - I don’t know how they do it today, or in other locations, but when I was in college (late '60s) we knew of a grade crossing near Ann Arbor Michigan where shorting one rail to the other near the crossing set off the signals. (OK - I was one of those “kids” I mentioned.) Indeed, with metal wheels and axels, trains “short” the two rails… complete a connection ( just like turning on a light switch completes a connection) for the signal-control and the signal goes off. We walked up and down the rails, and found the point beyond where the signal no longer went off when shorted - there was a point there where the rail continued on after a small gap formed by the two rail sections not quite touching. I’m sure there was a similar gap a similar distance away from the crossing in the other direction, leaving this section of rail several hundred yards either direction from the crossing which was connected by a wire to the signal control box (we located the wire) and the opposite rail also was connected by another wire to the box.
Then they put a relatively low voltage difference on the two wires, and anything shorting the rails completed the circuit and current flowed (through a relay no doubt back in 1965 - perhaps an electronic circuit today) and the crossing signal activated. We didn’t measure the voltage - we should have to make the experiment complete.
I expect the presence of a train in a block is sensed in a similar way, so the dispatcher’s displays and the block signals can react appropriately.
Hey, now - it wasn’t vandalism. We were young Electrical Engineering majors, it was a low-traffic area, and it was late at night. We were conducting “experiments” to see how it all worked. 
In the late '70s I worked for Dayton
I was taught that pure silver was a better conductor than gold, but it tarnishes so fast in air, that its resistance will increase greatly in time. I want to be an electrical engineer so I would like to know if this is true, because I feel it is important.
Adrianspeeder
Well, for those of you that have served, remember, the two most useless ranks, O-1 and O-4 (Ensign/2LT and Lieutenant Commander/Major) are gold and the rest of the ranks are in silver…so there must be some merit to that argument
I learned the AF ranks many years ago, so this really cracked me up!
La Mook [:D]