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#1
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I was wondering all this neet posting about lightning
i understand that lightning wants to find path of least resistance if my antenna is grounded, so over other objects on the roof, including the brick building itself nearby trees etc wouldn't my antenna then become the 'best' ground ie path of least ristance and thusly ""attract"" the lightning i get confused since, my antenna being a good conductor and grounded (both pairs when not using it) will thereby dissapate ''static'' or ionic buildup and so i think wouldn't that sorta make lighting not become super attracted to seek it out?? dunno which takes the lead here?? thanks m |
#2
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ml wrote:
"wouldn`t my antenna then become the "best" ground or path of least resistance and thusly ""attract"" the lightning." That seems right and conductivity does not have to be high. Ben Franklin found the conductivity of twine sufficient. He drained charge from the atmosphere by placing fis kite high. Height is shown to attract lightning bolts to grounded towers used for various purposes. Many are hit by nearly every passing thunderstorm. Towers take lightning bolts. They don`t always if ever discharge the earth and atmosphere in their area to eliminate hits. They do seem to divert strikes in their vicinity and offer some protection to their surroundings. I`ve spent years in broadcast plants and seen many lightning strikes. If you build it they will come. Best regards, Richard Harrison, KB5WZI |
#3
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![]() "Richard Harrison" wrote in message ... Height is shown to attract lightning bolts to grounded towers used for various purposes. Many are hit by nearly every passing thunderstorm. Towers take lightning bolts. They don`t always if ever discharge the earth and atmosphere in their area to eliminate hits. They do seem to divert strikes in their vicinity and offer some protection to their surroundings. I`ve spent years in broadcast plants and seen many lightning strikes. If you build it they will come. Best regards, Richard Harrison, KB5WZI Saw a program on lightning a year or so back that described the mechanism involved in setting up a lightning strike. Every raised object in a fairly large area below an accumulating cloud charge sends up a stepped "leader"of opposing charge, all these "leaders" advance in steps that also zig and zag randomly upward. If I remember correctly the charge in the cloud is also sending out multiple feelers in a zig zag process. When one of the clouds feelers completes a circuit by meeting a leader from the ground the circuit completes and all hell breaks loose. It's all relatively random and the leader from a golfers head may just connect before the leader from a much taller tree or tower connects. if he's a lucky golfer the taller stuff will make the connection. I've seen weather service warnings lately indicating that anything within a 25 mile radius of a stormclouds center has a chance of winning the electrical lottery. When I see lightning as I'm mowing my 7 acres here in southern Oklahoma, I now shut down and make for the house.If I have an inkling we're gonna see weather I bag the terminal end of my various coax connections before the weather starts and coil them outside away from the house Harold KD5SAK |
#4
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![]() "Harold Burton" wrote in message ... "Richard Harrison" wrote in message ... Height is shown to attract lightning bolts to grounded towers used for various purposes. Many are hit by nearly every passing thunderstorm. Towers take lightning bolts. They don`t always if ever discharge the earth and atmosphere in their area to eliminate hits. They do seem to divert strikes in their vicinity and offer some protection to their surroundings. I`ve spent years in broadcast plants and seen many lightning strikes. If you build it they will come. Best regards, Richard Harrison, KB5WZI Saw a program on lightning a year or so back that described the mechanism involved in setting up a lightning strike. Every raised object in a fairly large area below an accumulating cloud charge sends up a stepped "leader"of opposing charge, all these "leaders" advance in steps that also zig and zag randomly upward. If I remember correctly you don't. there are exceptions, but in most of the cloud-ground lightning the 'stepped leader' starts down from the cloud. it progresses downward in 50-100m steps bringing charge down from the cloud with it as it progresses (most often negative charge). as it gets closer to the ground it attracts the opposite (usually positive) charge under it, when the field strength is high enough streamers start up from the ground and connect with the stepped leader and the bolt that you see is triggered. streamers from the ground are normally not stepped, they are a single breakdown between the ground (or some other object) and the downward leader usually no more than about 100m long. the final attachment point for the stroke depends on which streamer coming up connects to the leader coming down first. |
#5
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Richard Harrison wrote:
ml wrote: "wouldn`t my antenna then become the "best" ground or path of least resistance and thusly ""attract"" the lightning." That seems right and conductivity does not have to be high. Ben Franklin found the conductivity of twine sufficient. He drained charge from the atmosphere by placing fis kite high. Height is shown to attract lightning bolts to grounded towers used for various purposes. Many are hit by nearly every passing thunderstorm. Towers take lightning bolts. They don`t always if ever discharge the earth and atmosphere in their area to eliminate hits. They do seem to divert strikes in their vicinity and offer some protection to their surroundings. I`ve spent years in broadcast plants and seen many lightning strikes. If you build it they will come. I went on a tour of a TV station tower site last year, and they had a lightning suppression system that had a number of rods with a lot of fine metal (wires?) hanging off the ends - they looked a bit like a cheerleaders pom-pom. The individual rods hung from the sides of that tower at various heights on the tower. Height was either 1000 or 1200 foot IIRC. The station engineer noted that although it was still a noisy place when a storm was approaching, it was no where as exciting as it used to be! And yes, it did protect the area around the tower. I was very impressed with the mechanics of a large tower, such as the huge suspended weight/pulley system on the guy wires, The strange elevator that takes people up to do maintenance on the tower and guy wires, the icefall protection structures (the engineer lost a car once), and of course the foot thick solid copper jacket coax! - Mike KB3EIA - |
#6
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![]() "Mike Coslo" wrote /snip/ I went on a tour of a TV station tower site last year, and they had a lightning suppression system that had a number of rods with a lot of fine metal (wires?) hanging off the ends - they looked a bit like a cheerleaders pom-pom. The individual rods hung from the sides of that tower at various heights on the tower. Height was either 1000 or 1200 foot IIRC. And yes, it did protect the area around the tower. - Mike KB3EIA - Mike, The IEEE has nearly succeeded in quashing once and for all, the last ditch efforts of a desperate group of snake-oil salesmen pushing Early Streamer Emission (ESE) and Charge Transfer System (CTS) phony-science. The latest trick of these junk-science purveyors was to hire corrupt Russian scientists to publish "findings" that the ESE/CTS systems worked. Every other lightning expert in the world has rung-in on this already, and the theory is totally discredited, and without merit. That didn't stop some engineers at various plants and stations around the world from trying the systems those CTS snake oil salesmen pushed. The system you described on that tower is CTS. And it never worked, anywhere. Anyone who still defends it today is too embarrassed to admit they paid upwards of 10x the cost of proven Franklin-rod lightning systems, for a totally discredited design that leaves them dangerously exposed to damage from lightning (if it was the only protection system). Jack Painter Virginia Beach, Virginia |
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