[50mhz] [PNWVHFS] Update Cycle 24

[Bill VanAlstyne W5WVO]

Pete,

As more and more inexplicable things are observed about E-layer propagation 
on 6 meters, I'd be the last one to suggest that any idea is ridiculous. (I 
used to think that way, when I was a 6m newbie and thought I knew it all.) 
What is clear is that metallic meteors constantly drizzle into the 
atmosphere... They ablate, ionize (providing meteor-scatter propagation), 
and then slow down enough to recapture electrons, all at around 90 km up or 
so, plus or minus... And then, sometimes, they get themselves turned into 
ions again, seemingly in a variety of ways. And It is pretty clear at this 
point that we really don't understand all the ways this reionization can 
happen.

There is ample evidence that high-speed horizontal wind shear at about this 
height is responsible for a lot of the ionization that we call sporadic-E --  
but what causes the wind shear? What causes it to be seasonal? What causes 
it to happen more often at certain places on Earth and less often at other 
places (if that is actually true)? What part (if any) is played in these 
anomalies by irregularities in Earth's geomagnetic field? What part (if any) 
is played by coronal mass ejections during intense solar activity? What part 
(if any) is played by energetic events that occur in the troposphere or 
stratosphere? Some of these questions have hypotheses (and in a few cases 
some half-decent theories) attached to them, but we're a long way from 
understanding how it all works together.

So no ridicule from me. If somebody can come up with a reasonable model that 
suggests how tropospheric weather events can cause ionization of metallic 
atoms at 90 km or so up, I'd love to hear it. So far, I haven't seen any, 
but that in itself means nothing except that I am ignorant -- either more 
ignorant than scientists who know better, or at worst, just as ignorant as 
scientists who know no more than I do. :-)

Bill W5WVO


-----Original Message----- 
From: Pete
Sent: Tuesday, November 23, 2010 16:36
To: doc at kd4e.com
Cc: 50 MHZ Mailing List
Subject: Re: [50mhz] [PNWVHFS] Update Cycle 24

Doc,

I have often observed brief 6m openings while centered precisely between or 
on the edge of severe WX fronts, and was ridiculed for suggesting a 
connection, only because no hard data exists. Weather (and any propagation 
phenomena as a result) just changed too fast for a reasonable study... until 
now perhaps. Computer programming and capability have improved tremendously 
since I discussed this last around 1987. Maybe someone will pick up the 
torch.

Fifteen to twenty years ago, I remember a (2 part?) article in QST about 
this very topic, (severe thunderstorm fronts?) but aside from anecdotal and 
circumstantial events, I seem to recall that the theory was left unresolved, 
again mostly due to insufficient data. The article entertained the 
possibility that shear and front patterns may be what's RESPONSIBLE for 
producing ionization at VHF regions to stimulate Es as we know it, and NOT 
that the annual Es seasons happen to fall during the times of year we get 
the most violent weather.

The subject may have since been revisited in a publication I haven't seen or 
heard about, and anyone on the list can tell me if it has; I'd like to know.

One thing for sure; even if there ever comes a time when everything about 6m 
propagation becomes completely understood and predictable, it will never 
lose its charm for me as the Magic Band.

-Pete / NL7XM
_________________________
ʎɐqǝ uo pɹɐoqʎǝʞ ɐ ʎnq ı ǝɯıʇ ʇsɐן ǝɥʇ sı sıɥʇ

<doc at kd4e.com> wrote:
> Some 6M openings appear to be related to storm-fronts, it may be worth 
> making a study of geographically-regional openings cross-tabbed with 
> different types of weather patterns.
>
> It may prove an insufficiently-linked association to represent a 
> predictable pattern ... or maybe there are some associations to be 
> discovered for some 6m propagation forecasting.
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