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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 : [email protected]
> > [mailto:[email protected]]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
> >
> >
> >
>
>
>
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