Re: [IRCA] the big black absorptive cloud

["Donald K. Kaskey" <kaskeyfamily@xxxxxxxxx>]

The only experience I've had with this 'anomoly' was in 1955 from Keflavik, Iceland where I had decent to great reception of North America & Europe from October through the end of the year.
After New Years there was a monstrous drop off and I gave up and listened to the ham bands, which were very lively.

Don



Nick Hall-Patch wrote:

> At 14:40 03/11/2007, you wrote:
> >Hi Nick,
> >where do you find info about this cloud? I also noticed the same
> >wipeout here. Everything looked excellent still at 1200.
>
> I wish I knew, Mauno; I was joking at the time, but it seems to be a
> very real phenomenon, and one which, to my limited knowledge, still
> doesn't really have an observable solar / geomagnetic parameter
> associated with it.   What has changed since a day or two ago which
> has caused all long distance signal strengths to deteriorate so markedly?
>
> (forgive me, as I suspect you already know all the following) This
> deterioration (not always so sudden as today) was I believe initially
> described as the "mid-winter anomaly" in DX club literature in the
> sixties, and was applied to the general drop off of trans-Atlantic
> signal strengths observed as mid-winter approached, after the glory
> days of September and October.  This is an unfortunate term, because
> the same term is also used in academic literature to describe a
> daytime phenomenon of winter-time excessive absorption of signals in
> the D region, which doesn't seem to carry over to night, at least
> according to theory; I don't think I've ever seen empirical data on
> this.  To confuse the issue further, there also appears to be
> something called a "winter anomaly" associated with the F2 layer, and
> they don't appear related.
>
> At one time, some thought stratospheric warming was associated with
> this, but Carl Leutzselschwab, K9LA, the 160m propagation expert,
> pretty much debunked that in a couple of articles.
>
> I banged on about the MWA a couple of years back on the
> coastalroundtable group, but didn't get much interest at the time
> from other than John Bryant.  There are a number of references on the
> daytime winter anomaly, which you probably already have,  but
> nighttime winter anomaly conditions on medium wave just don't seem to
> have been researched particularly so far as I can tell.   So we're
> left with my not so mythical "big black absorptive cloud".
>
> best wishes,
>
> Nick
>
> >I received this from NOAA:
> >Space Weather Message Code: ALTEF3
> >Serial Number: 1397
> >Issue Time: 2007 Nov 03 0505 UTC
> >ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
> >Threshold Reached: 2007 Nov 03 0500 UTC
> >Station: GOES12
> >Observed Yesterday: Yes
> >Yesterday Maximum 2MeV Flux: 4620 pfu
> >
> >73, Mauno
> >
> >----- Original Message ----- From: "Nick Hall-Patch" <nhp@xxxxxxxx>
> >To: "Mailing list for the International Radio Club of America"
> ><irca@xxxxxxxxxxxxxxxx>
> >Sent: Saturday, November 03, 2007 4:22 PM
> >Subject: [IRCA] the big black absorptive cloud
> >
> >
> >>
> >>>   As for this morning, don't ask!   A COMPLETE wipe-out.  Not a
> >>>single audio heard between 13:47 and 14:05....first time this
> >>>season.  Doesn't look good, I'm afraid!  ...........Walt.
> >>
> >>Glad it's not just me.   I shouldn't have mentioned that (not so
> >>mythical?) absorptive cloud in the ionosphere, because it seems to
> >>have arrived over the Pacific Ocean this morning, there being no
> >>indication of geomagnetic activity on the NOAA site, just K-indices
> >>of zero and one overnight.
> >>
> >>audio traces on 612, 747 and 774 by 1420UT, just a few weak
> >>carriers otherwise.
> >>
> >>Nick
> >>
> >>
> >>
> >>
> >>****************************************************************************
> >>Nick Hall-Patch
> >>Victoria, B.C.
> >>Canada
> >>
> >>****************************************************************************
> >>
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>
> ****************************************************************************
> Nick Hall-Patch
> Victoria, B.C.
> Canada
>
> ****************************************************************************
>
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