NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction at the horizon.
From: Bill Noyce
Date: 2008 Mar 15, 15:10 -0400
From: Bill Noyce
Date: 2008 Mar 15, 15:10 -0400
George Huxtable wrote, concerning timing sunsets: > But on second thoughts, does that matter a jot?. No, it isn't a coastal > site, it's an ocean site, as far as sunset timings are concerned. Those are > only affected by what's going on in the atmosphere, further out than that > distant horizon. Atmospheric effects, between that horizon point and the > observation point, have no effect at all, inversions or not, because they > bend light from the Sun upper-limb and light from the horizon in EXACTLY the > same way. If I've got that right, the only relevant temperature profiles > would be those taken from 50 to say 150 miles out to sea. If Marcel knows of > such information, it could be of interest." 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? -- Bill N --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---