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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction at the horizon.
From: George Huxtable
Date: 2008 Mar 19, 20:50 -0000
From: George Huxtable
Date: 2008 Mar 19, 20:50 -0000
Marcel's graphs are plotted in terms of Zenith distance. But is this true zenith distance, or is it apparent zenith distance, after the light has been refracted? And whichever it is, if the plots were made instead in terms of the other one, and the ratios were computed for constant values of that other angle intead, would they look any different? Not that it would answer the problems. It's going to be hard to explain the very different amount of refraction change in response to a 10% increase in absolute temperature, and to a 10% reduction in pressure, either of which should have exactly the same effect on air density. If you made both those changes together, the air density should remain constant, and so the refraction should be unchanged. Judging from those graphs, that isn't going to happen. So the question needs to be asked- why the hell not? That may point to whatever's going wrong. George. contact George Huxtable at george@huxtable.u-net.com or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
