View Single Post
  #10   Report Post  
Parallax
 
Posts: n/a
Default LIGHTNING STRIKE PROBABILITY

"rnh17" wrote in message ...
How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...



As I said, effective area is defined as pi*9*(mast height squared).
This is comes from the distance over which a conductor over a flat
conducting plane (3* mast height) has minimal effect on the electric
field distribution(you know, the area of a circle being pies are
squared.

Telephone poles have conductors attached to them and normally have a
ground wire. Trees on the top of a tall hill all alone would not last
long if active thunderstorms passed over them often enough. Around
here, tall pines get hit and die while many other trees survive
strikes. Look at pines with vertical slashes on them running waaaay
up the tree, this is often caused by lightning strikes.

If you do not believe my 1 in 20 chance, consider the number of
golfers who get hit each year here in FL playing during thunderstorms.
Furthermore, find something wrong with my reasoning. Since the math
is correct, the only possibility is that the cloud to ground strike
rate is too high but I watched such strikes during a storm to get this
rate.

I believe my analysis is correct, and until I did this simple
calculation based on area, my experience with electrostatics had
caused me to think the probability should be MUCH higher with this set
of assumptions.