Return-Path: Received: (qmail 60454 invoked from network); 5 Jan 2005 21:59:08 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 5 Jan 2005 21:59:08 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CmJA4-0000Ob-Gi for dave@picks.force9.co.uk; Wed, 05 Jan 2005 21:57:52 +0000 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CmJA2-0000Ns-US for dave@picks.force9.co.uk; Wed, 05 Jan 2005 21:57:47 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1CmJBC-000KVo-TU for dave@picks.force9.co.uk; Wed, 05 Jan 2005 21:58:58 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CmJB6-0006VI-5p for rs_out_1@blacksheep.org; Wed, 05 Jan 2005 21:58:52 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CmJB5-0006V9-Ij for rsgb_lf_group@blacksheep.org; Wed, 05 Jan 2005 21:58:51 +0000 Received: from rwcrmhc13.comcast.net ([204.127.198.39]) by relay.thorcom.net with esmtp (Exim 4.41) id 1CmJB0-0002XZ-GL for rsgb_lf_group@blacksheep.org; Wed, 05 Jan 2005 21:58:51 +0000 Received: from 204.127.197.111 ([204.127.197.111]) by comcast.net (rwcrmhc13) with SMTP id <2005010521583201500cbfhbe>; Wed, 5 Jan 2005 21:58:37 +0000 Received: from [208.54.95.129] by 204.127.197.111; Wed, 05 Jan 2005 21:58:30 +0000 From: Warren K2ORS/WD2XGJ To: rsgb_lf_group@blacksheep.org Date: Wed, 05 Jan 2005 21:58:30 +0000 Message-Id: <010520052158.117.41DC630500081A5A0000007522007374780B97010D0A020E06979D0E03@comcast.net> X-Mailer: AT&T Message Center Version 1 (Nov 22 2004) X-Authenticated-Sender: bWFyeWphbmVib3lkQGNvbWNhc3QubmV0 MIME-Version: 1.0 X-SPF-Result: relay.thorcom.net: 204.127.198.39 is neither permitted nor denied by domain of comcast.net X-Spam-Score: 2.2 (++) X-Spam-Report: autolearn=no,HTML_20_30=0.504,HTML_MESSAGE=0.001,HTML_NONELEMENT_20_30=0.07,MIME_BOUND_NEXTPART=0.106,RCVD_BY_IP=0.024,RCVD_DOUBLE_IP_LOOSE=0,RCVD_NUMERIC_HELO=1.531 Subject: LF: Gravity Waves Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_MESSAGE, MIME_BOUND_NEXTPART,MIME_HTML_NO_CHARSET autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit

Alan,

The term "Gravity Waves" as used in geophysics (as opposed to astrophysics) refers to a wave at a density discontinuity whose restoring force is gravity. You are correct in making the analogy with waves on the ocean surface, ocean waves are a type of gravity wave. One can envison a similar phenomena wherever there is a pronounced disconinuity - such as at boundary between atmospheric or ionospheric layers (tropopause, stratopause, etc.)

In my mis-spent youth I did graduate studies in geophysics!

--
73 Warren K2ORS/WD2XGJ
FN42hi

-------------- Original message --------------

> Hi Jean-Louis, sometimes it does, but I think there are a lot of different
> frequencies stimulated. I have had a few attempts to fourier analyse the
> plots, but not with a great deal of enthusiasm yet. If I look at a lot of my
> recordings there are obviously cases of beats between "waves" of different
> periods. But theory.....well no not yet....I am an empiricist.....get the
> measurements first and find a theory to fit later.
>
> I think there are things called "gravity waves" talked about in the realms
> of atmospheric and ionspheric physics (KN4LF's MF Propagation site has a
> reference to them), but I have not yet found much else of interest
> yet,except on I think it was the NOAA site, a program that prints out a
> quasi 3d representation of an oscillating sphere. I can envisage a mechanism
> that attenuates the high frequencies first but have not tried to work it
> out. I think that ocean waves might be the nearest analogue. The problem is
> that unlike water, the medium has a rapidly reducing density. Maybe there
> are some keen mathematicians around who would care to play with the ideas.
> Also the CME and solar wind is an "electro-magnetic" interaction. If it were
> not for the earths field I think the solar ions would penertrate right down
> into the atmosphere.
> Like all things it is probably a lot more complex, but at least I have a
> handle to enable me to talk about it and gather ideas.
>
> Cheers de Alan G3NYK
> alan.melia(at)btinternet.com
>
> ----- Original Message -----
> From:
> To:
> Sent: 05 January 2005 12:09
&g t; Subject: LF: RE: Re: RE: Re: DI2AG 440KHz...rapid fading
>
>
> Hello Alan
>
> Thanks for your interesting suggestion.
>
> I'm wondering why the "oscillating mirror" frequency would decrease when
> time passes.
>
> The amplitude of a jelly portion wobble decreases when the losses dampen the
> oscillations, but not the frequency which remains stable.
>
> So I would expect some diminishing QSB amplitude on the DI2AG records, and
> not QSB frequency decrease.
>
> Please what is the underlying theory about this frequency vs time decrease ?
>
> 73
>
> Jean-Louis F6AGR
>
> > -----Message d'origine-----
> > De : owner-rsgb_lf_group@blacksheep.org
> > [mailto:owner-rsgb_lf_group@blacksheep.org]De la part de Alan Melia
> > Envoyé : mardi 4 janvier 2005 18:17
> > À : rsgb_lf_group@blackshee p.org
> > Objet : LF: Re: RE: Re: DI2AG 440KHz...rapid fading
> >
> >
> > Hi Jean-Louis, and Walter. I see a rapid almost cyclical
> > fading on some
> > 136kHz signals immediately after a geomagnetic storm (we have
> > had several
> > minor storms Kp=5 recently), the period usually lengthens on
> > successive
> > nights. I have suggested that this might be due to the plasma cloud
> > "slapping" the ionosphere on one side and it then "ringing"
> > like a wobbly
> > jelly ( I must have eaten too much this Christmas !!) This
> > would cause the
> > "reflection" level to move up and down a few hundreds of
> > metres maybe even a
> > kilometre, which is quite sufficient to swing through a
> > 180degree phase
> > change. The movement required for a "null" at 440kHz is much
> > less th an at
> > 136kHz. I would certainly be interested to see if the period
> > of the fades
> > increases over the course of the next few nights.
> >
> > Cheers de Alan G3NYK
> > alan.melia(at)btinternet.com
> >
> > ----- Original Message -----
> > From:
> > To:
> > Sent: 04 January 2005 13:48
> > Subject: LF: RE: Re: DI2AG 440KHz
> >
> >
> > > Walter et al.
> > >
> > > I recorded your DI2AG sigs last night from 6 PM to 6 AM .
> > > A quick exam on the 150 ARGO snapshots during my tea time early this
> > morning tend to show a deep QSB (period around 1 minute).
> > > Have you got other similar remarks ?
> > >
> > > 73
> > >
> > > Jean-Louis F6AGR
& gt; > > Loc. JN18DQ, near Paris
> >
> >
> >
>
>
>