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    Re: Q: how to calculate refraction at higher altitudes on land?
    From: Dov Kruger
    Date: 2002 Feb 28, 14:26 -0500

    Craig wrote:
    
    >If you can see the top of a nearby mountain, measure the angle above (or
    >below) horizontal, use the topographic map for mountain top coordinates,
    >waypoint mountain top and your position, obtain distance (easy with GPS),
    >use trigonometry for difference in opposite side, which is difference
    >between your height and mountain top, simple math, and voila!
    >
    
    This is an interesting idea, but you don't know your own altitude, and
    you therefore don't know the difference in altitude.
    You can use the current uncertain altitude as a starting point and
    iterate perhaps.
    
    If GPSs display the straight line distance between two points including
    altitude, then I am unaware of it. I do not even know if I can enter the
    altitude of a waypoint on my GPS.
    I don't think this is quite so easy as Craig says ;-)
    
    
    

       
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