[TenTec] OT: Lightning and Grounds

[CATFISHTWO@aol.com]

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 at 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..