Hi Chuck,
At 07:00 AM 11/2/02, Charles Hutton wrote:
>But the original subject that I was discussing is:
I understood. This has become become a rather lengthy and convoluted
thread. And I was attempting to comment on several of its disparate
aspects, perhaps not as clearly as I might have.
> "Thomas KN4LF Says: As a retired Meteorologist and Space Weather
> Forecaster
>I can say that temperature and moisture discontinuities in the vicinity of a
>cold front can refract 160 meter signals in unpredictable ways."
Chuck, I'll agree with you that there's absolutely nothing in the
Kazimirovsky & Kokourov review that's even peripherally related to a
physical mechanism that is based upon refraction at discontinuities.
A simple check of the order of magnitude of the possible effects shows why
refraction is simply the wrong place to be looking. The maximum difference
in the radio index of refraction between cold/dry air and warm/wet air is
less than 1 part in 1000. If such a discontinuity is placed approximately
perpendicular to the direction of propagation then the maximum angular
deviation one expects to see across the discontinuity is thousandths a degree.
>The Russian paper didn't touch on that subject, if my attention didn't
>wander too much while scanning it. I'm still curious as to whether there are
>studies on the long term effects of cold fronts, as opposed to the short
>term effects of lightning which is what some of the comments so far have
>been about.
Even though the specific mechanism of refraction is clearly not very
significant, it should not be surprising to eventually find some
correlation between fronts and ionospheric conditions. The effect may be
causal with fronts acting as a source of dynamic disturbances that generate
upwardly propagating waves. Or the effect may be indirect, with fronts
serving as surrogates for changes in the state of the lower atmosphere.
Both of these possibilities are hinted at by research that's referenced in
Kazimirovsky & Kokourov.
73,
Mike K1MK
Michael Keane, K1MK
k1mk@alum.mit.edu
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