NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Refraction at altitude
From: Gary LaPook
Date: 2012 Apr 16, 01:17 0700
From: Gary LaPook
Date: 2012 Apr 16, 01:17 0700
I have was contacted by a guy who figured that Fred Noonan didn't to need know the refraction correction from his 10,000 foot altitude to produce an accurate LOP by calculating the time of sunrise, he thought that you could just use the distance to the horizon table instead. I looked into it and I was surprised, it worked. Conceptually you are looking over the shoulder of a person on your horizon who is observing the sun rise from sea level and applying the standard 34' refraction correction for a sea level horizon shot. But you are actually looking downward toward that horizon by the dip of 97' so your Hs is actually  1° 37' and the refraction correction for that negative altitude is 50' from the refraction table in the Air Almanac. Any idea why this works? I have include my email to the guy that came up with this.  On Sun, 4/15/12, Gary LaPook <glapook@pacbell.net> wrote:
