Richard wrote:

On 3/9/2013 1:10 PM, Jim Wilkins wrote:
wrote in message
...
On 3/8/2013 7:01 PM, Michael A. Terrell wrote:
...

Tune to channel 13 and turn the brightness control down to the
point
where the image is nearly--not completely--black. Then turn to
channel
2. Lightning will register as horizontal streaks on the screen.
When the
picture becomes bright enough to be seen, or when the screen glows
with
an even light, there's a tornado within 20 miles, ...

What makes you think that's even remotely likely to be so?
Lightning isn't at all necessarily indicative of tornadic
activity--certainly tornadoes are spawned from t-storms, but I'm
pretty sure it's news to the folks in Norman (NOAA severe weather
office) there's predictive capability in the lightning...


We rarely have tornados but the idea of watching my spectrum analyzer
for lightning pulses sounds interesting. I put a scanner antenna on it
that receives 25 to 1300 MHz.

However the RF spectrum of lightning falls off far below Ch2, which
covers 54-60MHz:
http://www.stormwise.com/striking.htm
http://www.progettomem.it/appr_noise.php?id=5
When I was young I built a receiver and big loop antenna to listen to
sferics, tweeks and whistlers. Radiation from AC power lines drowned
out everything else unless I took it a few miles into the woods, which
is not a good place to be during a storm.

This is a commercial lightning indicator:
http://www.seaerospace.com/bfg/wx500pg.pdf

jsw



You are not looking for lightening!

Tornados create an electrical disturbance somewhere in the 55 megahertz
range, close to the frequency band assigned to channel 2.

With this phenomenon in mind, Newton Weller, an electronics technician,
has devised the following method for using your TV set as a tornado
warning device.

Tune to channel 13 and turn the brightness control down to the point
where the image is nearly--not completely--black. Then turn to channel 2.

Lightning will register as horizontal streaks on the screen.

When the picture becomes bright enough to be seen, or when the screen
glows with an even light, there's a tornado within 20 miles, and it's
time to find Toto and head for the basement.



Hard do with a modern TV with a digital tuner. They look for sync on
analog channels, and the right type of data stream for digital.
Otherwise they display the blue screen of contempt.