A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2019 Nov 23, 14:19 -0800
In winter I do pactice taking sights at 60°N 30°E across the Finnish Gulf.
Non-horizontality of ice is not the biggest source of erors, the most influencing one is by refraction. It is rarely that any table or formula is capable to account for the bizarre air temperature conditions over the icy surface.