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Fred,
I see, this sounds reasonable.
But then I need a barometer, or to correct
the pressure from the Weather channel for
my altitude, because,
if I understand correctly, the pressure broadcast
for the weather prediction is reduced to the sea level.

Alex

On Tue, 31 Oct 2006, Fred Hebard wrote:

>
>
> Alex,
>
> Use the actual pressure.  That is the determinant for the refraction
> correction.  The elevation above sea level has an insignificant
> effect on parallax, when you consider that the radius of the earth is
> about 3400 nautical miles, but significantly reduces refraction via
> the effect on barometric pressure.
>
> Fred
>
> On Oct 31, 2006, at 8:27 AM, Alexandre E Eremenko wrote:
>
> > Related question: the barometric pressure in the refraction formula.
> > Should I use the actual pressure at my observation site,
> > or should I "reduce it to the sea level"?
> > The actual pressure at my site reflects not only the deviation
> > from the standard atmosphere but also my altitude over the sea level.
> >
> > Alex
> >
>
>
> >


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