From: Brian Atkins (brian@posthuman.com)
Date: Thu Jul 15 1999 - 21:50:22 MDT
Ocean/lake waves do not get their energy from gravity. They get
it from sustained winds or from earthquakes. Tides are caused by
gravity. Gravity may be necessary though for water wave formation
(something has to pull the water down when the wind pushes it up)
which is maybe what was being said.
Rob Harris Cen-IT wrote:
>
> > On Mon, 12 Jul 1999 13:23:50 +0100 Rob Harris Cen-IT
> > <Rob.Harris@bournemouth.gov.uk> writes:
> >
> > [Ron Kean]
> > >> Gravity waves are a different phenomenon than gravitational waves.
> > >> Gravity waves are waves
> > >> consisting of the motion of fluid matter in a gravitational field.
> > >The
> > >> ripples on the surface of a pond are called gravity waves.
> > >>
> >
> >
> > > Are you certain about this? I don't remember any of this when
> > >I did
> > >A level Physics. I would call waves in water exactly that: water
> > >waves,
> > >sound = air waves, light = wave in some kind of electromagnetic ether
> > >(spacetime?) - I don't know this part at all - anyone got the info?
> > >
> > > Rob.
> > >
> > >
> >
> >
> > Certainly surface waves in water can be called water waves, and usually
> > are (in a non-technical context), without any misunderstanding. But
> > sound travelling through water can also be called 'waves in water', so
> > the term 'water waves' is technically imprecise, or ambiguous. So the
> > waves on the surface of a pond are better called 'gravity waves along a
> > water-air fluid interface', or just 'gravity waves' for short, since
> > their propagation depends on the interaction between the earth's gravity
> > (which is perpendicular to the surface of the pond) and the density,
> > viscosity, and surface tension of the water. Without gravity those waves
> > won't happen. That's why they're called 'gravity waves', as a technical
> > term.
> >
> So, the name of the wave comes from the source of it's energy - in this case
> gravity. Not, as I thought before, the medium in which the wave exists......
> Is this correct?
> BTW - cheers for the fine explanation !
>
> Rob.
>
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