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    Re: Refraction at the horizon.
    From: George Huxtable
    Date: 2008 Mar 15, 19:52 -0000

    Bill Noyce wrote-
    
    | 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?
    
    It's zero. By definition, a light-ray that just grazes the ocean surface has
    only one possible direction; tangential to that surface, and therefore
    horizontal at that point.
    
    George.
    
    contact George Huxtable at george---.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
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