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#1
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There is much correspondence on these walls about protecting equipment
and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. |
#2
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I think most of us choose to ignore risks that are beyond our
perceived control. We have some pretty violent storm activity in the area I live (central North Carolina) but death and structure damage seem to be rare. Most of the time the human body represents a higher impedance path than its surroundings. On the other hand, electronic property damage is common. It seems to go with certain locations. I live in one of those locations and I have taken all of the precautions I can think of over the winter months. We have had a couple of storms in the past week without noticeable damage. I am certain that the house took a hit on Saturday morning on the new lightning rod system at the east end of the structure. It sounded different than the usual damaging strike. It was more of a drawn out event (half a second or so) than the damaging explosive sound. I am speculating of course. Last night a less threatening storm came through with no damage noted. However I have two Labrador Retriever dogs, "Shadow" an 85 pound black female that is especially smart, and "Bear" 130 pounds of white macho male. Shadow always takes refuge in the bath tub and Bear gets as close to me as he can for a storm. Last night I spent two hours on the floor comforting Bear during the storm and wondering if the dogs might simply be smarter than I! I have had strikes in the past that resulted in "fireballs" bouncing through the room. The dogs came by the fear as a result. IMHO, the difference between bravery and stupidity is how you choose to perceive it! On a more positive note, I worked Italy, Spain, Wales and Poland on 20 meters yesterday afternoon with my new TenTec Jupiter transceiver. I believe this little ridge is a very good radio location... de W8CCW John On Wed, 26 Apr 2006 11:50:05 +0100, "Reg Edwards" wrote: There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. John Ferrell W8CCW |
#3
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A often faulty memory seems to recall that lightning deaths in the USA
are generally around 75/year and several hundred injured. Mostly, these occur at outdoor events such as picnics, barbecues, ball games, etc. As is stated in another response: if you can't control it we tend to ignore it. /S/ DD, W1MCE Reg Edwards wrote: There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. |
#4
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Reg:
Every year there are a few reports of people struck by and often killed by lightning. Indeed Florida is the leading place in the whole world for lightning activity and lightning deaths. In Florida we have really vicious thunderstorm activity throughout the summer months. These storms come up fast, thunderheads rising upwards of 50,000 feet, with black wall clouds decending to ground level and the air thick with static and rain so hard that you cannot see more than 25 feet. Impressive stuff! I have never personally met anyone who was struck by lightning. One of my own [arbitrary length] dipoles was simply vaporized by a strike when I was not at home... the ladder line that fed it's center was also missing and there was a two foot diameter hole about a foot deep in the lawn where I had left the end of the line laying on the ground. That's where I place the ladder line when not in the shack. When I returned home after that storm, I found the rope ends at the two supports simply swinging in the wind with the insulators on the ends still intact. During the annual ARRL Field Day event, held at the peak of Florida lightning season, in June of each year, I/we quickly disconnect feedlines and throw them well away from the transmitter sites during thunderstorm approach, on several occasions during those Field Days, and from a distance and under appropriate shelter, I have personally watched arcs jumping across the air gap between the conductors of the end of ladder line lying on the ground during the passage of thunderclouds. But I have never witnessed an actual strike on one of those antennas. I don't have statistics at hand, but I can relay that most of the news reports of lightning deaths that I recall here in Florida were of the deaths of unfortunate golfers who failed to take shelter during a thunderstorm approach. I do recall a news report of someone killed by lightning on a Florida beach within the past couple of years. It would be my guess that most who are struck by lightning in Florida are visitors... As far as I can tell, most folks who live in Florida year round are very well aware of the dangers of lightning and take appropriate cautions. -- Pete k1po Indialantic By-the-Sea, FL "Reg Edwards" wrote in message ... There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. |
#5
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Peter O. Brackett wrote:
Reg: Every year there are a few reports of people struck by and often killed by lightning. Indeed Florida is the leading place in the whole world for lightning activity and lightning deaths. In Florida we have really vicious thunderstorm activity throughout the summer months. These storms come up fast, thunderheads rising upwards of 50,000 feet, with black wall clouds decending to ground level and the air thick with static and rain so hard that you cannot see more than 25 feet. Impressive stuff! I have never personally met anyone who was struck by lightning. One of my own [arbitrary length] dipoles was simply vaporized by a strike when I was not at home... the ladder line that fed it's center was also missing and there was a two foot diameter hole about a foot deep in the lawn where I had left the end of the line laying on the ground. That's where I place the ladder line when not in the shack. When I returned home after that storm, I found the rope ends at the two supports simply swinging in the wind with the insulators on the ends still intact. During the annual ARRL Field Day event, held at the peak of Florida lightning season, in June of each year, I/we quickly disconnect feedlines and throw them well away from the transmitter sites during thunderstorm approach, on several occasions during those Field Days, and from a distance and under appropriate shelter, I have personally watched arcs jumping across the air gap between the conductors of the end of ladder line lying on the ground during the passage of thunderclouds. But I have never witnessed an actual strike on one of those antennas. I don't have statistics at hand, but I can relay that most of the news reports of lightning deaths that I recall here in Florida were of the deaths of unfortunate golfers who failed to take shelter during a thunderstorm approach. I do recall a news report of someone killed by lightning on a Florida beach within the past couple of years. It would be my guess that most who are struck by lightning in Florida are visitors... As far as I can tell, most folks who live in Florida year round are very well aware of the dangers of lightning and take appropriate cautions. -- Pete k1po Indialantic By-the-Sea, FL "Reg Edwards" wrote in message ... There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. But are the thunderclouds lumped elements or transmission lines, peter? 73, Tom Donaly, KA6RUH |
#6
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Hi Tom:
Hmmm... Thunderclouds, lumped or distributed? It all depends upon the application requirments... if the occurence is infrequent one may make a quasi-static assumption and invoke DC conditions. Then we can make an approximation and treat the lightning stroke just as a DC conductor. Now... Just what is the steady state DC value for a lightning stroke? Ignoring the parasitic capacitance between strokes... we can approximate it as a long vertical wire, without loading... Then... Well you get the picture [grin]. Incidently we are in a very unusual dry spell here on the barrier island off Florida's East coast... we have only had about 1/8 inch of rain in the past three months, and the whole County is on fire! Regards, -- Pete k1po Indialantic By-the-Sea, FL "Tom Donaly" wrote in message . net... Peter O. Brackett wrote: Reg: Every year there are a few reports of people struck by and often killed by lightning. Indeed Florida is the leading place in the whole world for lightning activity and lightning deaths. In Florida we have really vicious thunderstorm activity throughout the summer months. These storms come up fast, thunderheads rising upwards of 50,000 feet, with black wall clouds decending to ground level and the air thick with static and rain so hard that you cannot see more than 25 feet. Impressive stuff! I have never personally met anyone who was struck by lightning. One of my own [arbitrary length] dipoles was simply vaporized by a strike when I was not at home... the ladder line that fed it's center was also missing and there was a two foot diameter hole about a foot deep in the lawn where I had left the end of the line laying on the ground. That's where I place the ladder line when not in the shack. When I returned home after that storm, I found the rope ends at the two supports simply swinging in the wind with the insulators on the ends still intact. During the annual ARRL Field Day event, held at the peak of Florida lightning season, in June of each year, I/we quickly disconnect feedlines and throw them well away from the transmitter sites during thunderstorm approach, on several occasions during those Field Days, and from a distance and under appropriate shelter, I have personally watched arcs jumping across the air gap between the conductors of the end of ladder line lying on the ground during the passage of thunderclouds. But I have never witnessed an actual strike on one of those antennas. I don't have statistics at hand, but I can relay that most of the news reports of lightning deaths that I recall here in Florida were of the deaths of unfortunate golfers who failed to take shelter during a thunderstorm approach. I do recall a news report of someone killed by lightning on a Florida beach within the past couple of years. It would be my guess that most who are struck by lightning in Florida are visitors... As far as I can tell, most folks who live in Florida year round are very well aware of the dangers of lightning and take appropriate cautions. -- Pete k1po Indialantic By-the-Sea, FL "Reg Edwards" wrote in message ... There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. But are the thunderclouds lumped elements or transmission lines, peter? 73, Tom Donaly, KA6RUH |
#7
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In article . net,
Peter O. Brackett wrote: But are the thunderclouds lumped elements or transmission lines, peter? Hmmm... Thunderclouds, lumped or distributed? It all depends upon the application requirments... if the occurence is infrequent one may make a quasi-static assumption and invoke DC conditions. I suspect that they're more correctly modelled as resonant circuits... specifically, as quartz-crystal oscillators. I keep hearing pilots talk about "clouds full of rocks"... -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#8
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Peter O. Brackett wrote:
Hi Tom: Hmmm... Thunderclouds, lumped or distributed? It all depends upon the application requirments... if the occurence is infrequent one may make a quasi-static assumption and invoke DC conditions. Then we can make an approximation and treat the lightning stroke just as a DC conductor. No!! A much better model is a capacitor arcing over. The current in the strike goes from zero to Imax [100,000 amperes] in less than 1 microsecond. This is followed by a decaying current [approximate exponential decay] that reaches 'steady state' in several 10s of milliseconds. This is followed by an secondary exponential decay of up to 500 milliseconds at somewhere around 500 to 600 amperes [this is basically the sustaining or continuing channel current. The static we hear is caused by the displacement current in the initial discharge. The bandwidth of the static is determined by the rise and fall times of the initial discharge characteristics. Now... Just what is the steady state DC value for a lightning stroke? 90% of all lightning strikes in the USA have a "continuing channel current" [long term channel current] of less than 600 amperes. It continues for less than 1 second. Ignoring the parasitic capacitance between strokes... we can approximate it as a long vertical wire, without loading... Balanced SNIPPED |
#9
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On Wed, 26 Apr 2006 11:50:05 +0100, "Reg Edwards"
wrote: There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? .... What on earth made you think that hams are generally safety conscious? From my experience, I suggest that most place little value on safety (fire safety, electrical safety, safe working at heights, safe vehicular installations, protecting immediate family and other would be rescuers from risk in the event of an accident). I am not saying that no one does it, just very few. A walk around most amateur stations reveals uncontrolled hazards. And the statistics say that the probability of adverse outcome is low. So in an unconscious risk managed approach, it seems most people assess that "it won't happen to me". Owen PS: there are standards or codes that relate to lightning and electrical hazards in most modern jurisdictions, but amateurs seem rarely familiar with them, and to the extent that there is any compliance, it is entirely accidental and unintended. -- |
#10
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![]() "Reg Edwards" wrote in message ... There is much correspondence on these walls about protecting equipment and property from lightning strikes. But there is never anything said about protecting people. Where are your concerns? In this country, UK, I can't remember the last time I read in the newspaper about anybody being killed by lightning. It is extremely rare. It doesn't appear to give US citizens much cause for concern. Are you all very brave? Or have you just got used to it. Just curious. What is the annual death rate due to lightning, per head of population, in states like Florida? Do you keep statistics? How does it compare with the death rate from being chewed to death by alligators in Florida swamps? Or dying from rattlesnake bites in Arizona? Does lightning make it to the newspapers? ---- Reg. http://www.torro.org.uk/TORRO/research/lightning.php |
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