NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction at the horizon. was: Re: Celestial Navigation without a sextant.
From: Marcel Tschudin
Date: 2008 Mar 14, 23:47 +0200
From: Marcel Tschudin
Date: 2008 Mar 14, 23:47 +0200
I missed to reply on one important item: George wrote: > refraction depends on temperature gradients at FAR greater heights.[than the observer near sea level] The word far (even written in upper case) may lead here to a misunderstanding. The air layers near the observer (below his eyes and above them) contribute most to the total refraction. Air layers high above him contribute only an epsilon to the total. In case of inversions, only those in layers close to the observer may cause ducting (infinite refraction); an inversion at a layer having a great distance (in height) to the observer can't produce ducting because the angle of incidence is too large. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
