Hi Dave,
> When a rain or snow storm moves toward the my location the noise level
> rises precipitously (no pun intended). Especially in the case of snow
> storms. On 160m I can hear them coming hours before they arrive. The
> noise is not due to contact by rain droplets or snow flakes upon my
> antenna's elements as the precipitation has not yet reached my
> location.
I observe the same effect, except I have low-height directional
receiving antennas that are up to 1/2 mile from my transmitting
antennas.
> I expect some of what I'm hearing is the electrical noise generated by
> the rain or snow interacting with the metal roofs of buildings,
> bridges, and the electrical grid network many miles away.
Not in my experience, or the experience of others.
1.) When I start hearing precipitation static, the direction of noise is
always from the direction of my tallest tower.
2.) When others observe this noise, they hear it much less on low
antennas. The same source is "supplying" the rain or snow hitting
all the antennas, yet the lower antennas (despite being struck by
just as much moisture) are much quieter.
3.) The noise on a high directional antenna out in the clear prior to
moisture hitting it is always non-direction. If the noise was
propagated in from even a few hundred feet, it would be directional.
4.) Having been on tall structures long before the storm hits, I've
heard sharp points protruding from the structure "sizzle" and get
louder and louder until lightning discharges in the distance. The
tower goes quiet at the exact moment of the strike, and then
smoothly builds up corona again.
It is pretty clear the noise comes from the antenna or other objects near the
antenna that have corona discharge.
> So perhaps there is a combination of things happening here, not just
> the direct noise from charged rain and snow particles dis-charging on
> the antenna elements but also electrical noise from faulty grid
> components and just the billions of rain and snow flakes dis-charging
> on the planets surface.
I don't think a small particle could carry enough charge to create a
problem like that. Remember it would have to greatly affect the
charges in the conductor it hits, since that would be the "antenna"
that radiates or conducts the noise to the receiving system. If the
noise was from thousands or millions of charged droplets "hitting"
something and discharging it would sound like white noise...not a
sizzle.
73, Tom W8JI
w8ji@contesting.com
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