All of this information is covered in the paper on Lightning Protection for
the Home and Station.
Yes, there is clear factual evidence that the initiation of a lightning
stroke is two fold. Streamers from the ground upward do exist as well as
streamers from the clouds downward. The entire objective of a lightning
protection system is to provide an ignition means to control the currents
with minimum or no damage. The overall construction and implementation of
system grounding will achieve this goal.
73
Bob, K4TAX
----- Original Message -----
From: <CATFISHTWO@aol.com>
To: <tentec@contesting.com>
Sent: Friday, July 01, 2005 1:49 PM
Subject: Re: [TenTec] OT: Lightning and Grounds
>
> In a recent science channel show there is a couple of shots describing
> most
> lightning striking initialy from the ground up. There are "streamers" or
> fingers of modest electron flow from the ground which actually initiates
> the
> strike. Comments from the "experts" claimed every thing from a grounded
> structure can actually cause lightning to develop from its ground, to the
> good
> grounds dissipate the charge and help prevent lightning.
>
> They also shot small rockets trailing a grounded wire into clouds and
> caused
> strikes, and in some of those the initial strikes is from the ground up
> not
> going from the cloud to the earth. They also showed a couple of
> different
> types of lightning such as some really incredibley powerful strikes (
> several
> hundred times the ground strikes , called super lightning) between two
> clouds, also going from the bottom cloud to the top cloud, and several
> other
> phenomena such as st. elmos fire , and lightning strikes on aircraft,
> which usually
> cause very little damage considering what could be possible
>
> So bottom line is the jury is still out on a lot of stuff we don't know
> about lightning in general, how it decides to strike, how it strikes, and
> such.
> The photography showing a strike orignating from the ground up was
> astounding,
> you could actually see small tendrils of lightning ( current, power??)
> form
> from the ground and reach up and as they approched the cloud the strike
> jumped
> from the cloud to the tendril and then down.
>
> Thank goodness we only deal with those here in northern california
> infrequently. Usually only a couple to 4 or 5 bad thunder and lightning
> storms per
> year here, and those usually well in the distance.
>
> Remember light travels at 186,000 miles per second ( almost instantanious)
> and sound travels in air at about 1100 feet per second, so when you see
> the
> flash, count "one thousand and one, one thousand and two, and for every 5
> seconds, the lightning is a mile away, so if you make it to one thousand
> and
> fifteen, the strike was roughly 3 miles away. a fun tidbit.
>
> tom N6AJR
>
>
>
> In a message dated 7/1/2005 7:24:23 A.M. Pacific Standard Time,
> rdetweil@hotmail.com writes:
>
> Reminds me of the phrase, "Lightning follows the path of least
> resistance."
>>
>>That phrase is true but I believe lightning follows all the other paths,
>>too.
>>
>>73, Mike N4NT
>>
>
> Well, if the ground system can handle the current load of a lightning
> strike, then like water, it's not going to flow up hill, If the ground
> system can't handle the current, then it will backup just like a dam and
> flow into everything else.
>
> If I had it to do over, I'd still add more stuff in my ground system..
>
>
>
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|