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    Re: Refraction at the horizon.
    From: Bill Noyce
    Date: 2008 Mar 15, 15:10 -0400

    George Huxtable wrote, concerning timing sunsets:
    >  But on second thoughts, does that matter a jot?. No, it isn't a coastal
    >  site, it's an ocean site, as far as sunset timings are concerned. Those are
    >  only affected by what's going on in the atmosphere, further out than that
    >  distant horizon. Atmospheric effects, between that horizon point and the
    >  observation point, have no effect at all, inversions or not, because they
    >  bend light from the Sun upper-limb and light from the horizon in EXACTLY the
    >  same way. If I've got that right, the only relevant temperature profiles
    >  would be those taken from 50 to say 150 miles out to sea. If Marcel knows of
    >  such information, it could be of interest."
    I think the refraction between the observer and his horizon *does*
    make a bit of difference in how sunsets are timed.  Specifically, it
    affects how distant that horizon actually is, and therefore affects
    the direction of the light-ray that just grazes the ocean surface.
    How big is this effect?
        -- Bill N
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