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    Re: horizon visibility puzzle
    From: Victor Reijs
    Date: 2001 Jun 22, 5:28 AM

    Hello Aubrey,
    
    I have some javascript for this:
    http://www.iol.ie/~geniet/eng/refract.htm#sea
    I you use for local height: 777 m
    and for distant height: 401 m
    and distance between the two 35 km
    You see that the apparent altitude of the distant height is -0.73�
    The sea is from the local hill is: -.79�
    So the sea is not visible!
    
    If we decrease the distant hill to 366 m, the sea becomes visible.
    
    All the best,
    
    
    Victor
    
    P.S. I am using formulas from Thom (see the text in the page).
    
    
    Aubrey O'Callaghan wrote:
    >
    > Basically this is a distance to horizon problem:
    > On the 777 m hill you can see:
    > 1.144 sqrt( 777*3.281) = 57.76 n. miles
    > On the 401 m hill you can see
    > 1.144sqrt(401*3.281)= 41.5 n miles
    > now hills are 35 km apart 35/1.8=19.44 n. miles
    >
    > If 777 and 401 m hill were at same place the difference in distance viewed
    > would be 16.26 n miles
    > If we move 401 m hill forward 16.26 n miles we can both see the same point.
    > Therefore this is the line cutting both top of both hills to horizon.
    > But we have moved it forward 19.44 n .miles so 401 hill will block 777 hill.
    >
    > We cannot see the ocean from 777 hill due to presence of 401 hill.
    >
    > Aubrey.
    >
    > At 03:17 PM 20-06-01, you wrote:
    > >You are ashore, 777 meters above sea level, looking toward the ocean.
    > >In your line of sight, 35 kilometers away, is a hill 401 meters high.
    > >Can you see the ocean over the top of this hill?
    > >
    > >This is an actual question someone has asked. I've come up with an
    > >answer, but am curious how others might solve the problem. One person
    > >approached it from a completely different direction than I used but
    > >got the same answer.
    > >
    > >--
    > >
    > >
    > >paulhirose---.net (Paul Hirose)
    
    --
    URLs: http://www.iol.ie/~geniet
          http://www.iol.ie/~geniet/eng/archaeocosmology.htm
          http://www.iol.ie/~geniet/maeshowe
          http://www.iol.ie/~geniet/setrise
          http://www.iol.ie/~geniet/irishstones
          http://www.iol.ie/~geniet/stpatrick
    

       
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