NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Dip
From: Alexandre Eremenko
Date: 2021 Mar 5, 20:16 +0000
From: Alexandre Eremenko
Date: 2021 Mar 5, 20:16 +0000
I remember seeing this many times in my childhood, when traveling by ship in Black sea. The article says incorrectly that this phenomenon is rare in moderate latitudes. In the later years I did not travel much by ships, but once we measured Sun altitude with Bill, on lake Michigan, with two different sextants, and when correcting our observations discovered a huge systematic error. This case has been reported on NavList, and after a long discussion it was concluded that the most likely explanation was "anomalous dip" which should be called more correctly "anomalous refraction at the horizon". In all these cases that I remember the weather was very nice (like in the photo), and there was absolutely no reasons to expect that something was wrong. Alex.