NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: horizon visibility puzzle
From: Hal Mueller
Date: 2001 Jun 20, 2:25 PM
From: Hal Mueller
Date: 2001 Jun 20, 2:25 PM
At 12:17 PM -0700 6/20/01, Paul Hirose wrote: >You are ashore, 777 meters above sea level, looking toward the ocean. Horizon distance is 58.4 nm from your location, or 108.2 km. There's a point out on the ocean, call it A, which is on the line containing your position and the hilltop. "A" is the farthest point on that line that you can see (and it's the farthest point that someone at sea level can see you). >In your line of sight, 35 kilometers away, is a hill 401 meters high. Horizon distance is 42.0 nm from this hilltop, or 77.8 km. >Can you see the ocean over the top of this hill? Point A is (108.2 - 35) km from the hilltop, or 73.2 km. You can see the hilltop from Point A. Thus, the hilltop blocks your view from your ashore location. ---- Hal Mueller hal@mobilegeographics.com Mobile Geographics LLC http://www.mobilegeographics.com/ Seattle, Washington (206) 297-9575 Get CelestNav 2.2.2! http://www.mobilegeographics.com/celestnav/
