"Shortwave Sportfishing" wrote in message
...
On Sun, 11 Dec 2005 17:44:44 -0800, "-rick-" wrote:


"Shortwave Sportfishing" wrote wrote ...

Another interesting phenomena is wind sheer at this set of
frequencies. If the prevailing wind is from the right direction,
sometimes you can hear conversations and calls from as much as 200
miles distance - sometimes even more. It happens in the spring and
fall more than any other time.

Hey Tom,

I've never heard of wind significantly effecting EM wave propagation. Do you
have a reference handy? I'd like to understand it and google came up empty.

Of course it does - how do you think Doppler radar measures wind
speed? Or radar for that matter?


Um... I thought by measuring the change in time or carrier phase/frequency
associated with a reflection, certainly not by measuring attenuation associated
with wind.


I will admit that they are at
higher frequencies, but it happens all the time at lower frequencies.
It happens mostly in the Spring and Fall along pressure/wind fronts,
mostly those moving from south to north. For example, where I live,
several radio stations that I like to listen to are marginal in terms
of signal strength - in particular at the 96.9 frequency. When the
weather is right, WTTK in Boston is obliterated by WFPG in Atlantic
City, NJ - usually short duration until the front passes. Happens
with WEEI, 103.7 by WMGM also in Atlantic City, NJ. Several New York
stations and one in PA when it all is right.

It does happen. You just have to pay attention and listen for it.

No references?

-rick-