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Re: horizon visibility puzzle

Subject: Re: horizon visibility puzzle
From: Victor Reijs (geniet@XXX.XXX)
Date: Fri Jun 22 2001 - 07:27:39 EDT

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@XXX.XXX (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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