>
> Good point. At higher altitude, the dielectric strength of air is
less, so
> the voltage cannot build up as much before the strike starts, so the
> clouds
> cannot build as much energy as they can in Florida.
>
> 73,
> Didier KO4BB
>
> At 07:41 AM 3/22/2004, you wrote:
> > From personal experience there is a lot of lightning in CO,
> >but the intensity is somewhat less since the ground elevation
> >is at 5,000 ft so the storms have 5,000 ft less elevation to
> >develop their charge.
>
statistically the change is relatively small. In a typical area of
central Florida the median stroke current is about 25kA, where in
central Colorado it is about 20kA. In the highest current range
(200-300kA) there are actually more strokes in Co .03% vs .02% in Fl.
Note, the database my software uses only covers 10 years so there is
still probably a fair amount of uncertainty in it.
A note on observing single storms. I have also seen the phenomena
mentioned where lightning seems to stop before it reaches my station and
then starts again on the other side. However in examining the
distribution of strokes for that time period it showed that the storm
approaching me was dying and the strokes were spaced out well before
they could have 'seen' my tower farm, and then a new (or rejuvenated)
cell started striking again on the other side. In my case I am near the
high point on a long wide n-s oriented ridge so it is not uncommon for
cells to be steered or disrupted by the uplift on one side... and I have
fairly frequently seen cells develop quickly on the eastern downslope
even when there was nothing to the west. A good analysis of strokes to
an area as small as a ham station would take many years of data,
probably much more than is available in the current u.s. dataset. Even
for detailed studies of power lines the minimum size data block we
normally use is 10 minutes on a side (about 10mi) and we average the
data over a 10 year period.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|