NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction.
From: Frank Reed CT
Date: 2004 Jul 9, 04:57 EDT
From: Frank Reed CT
Date: 2004 Jul 9, 04:57 EDT
I wrote earlier:
"So the net refraction (standard plus the weather front) is 4" of arc TOWARDS the zenith on one side of the zenith and 2" of arc AWAY from the zenith on the other side.
Make sense?"
Did that resolve the matter for everyone, or no? John B, does that make sense for you? You asked for a specific example (but that post more or less coincided in time with the above example so you may have missed the details). The conclusion is YES, the net refraction CAN place a star's apparent position lower in the sky than its true position, but rarely and not by much.
By the way, I don't think temperature inversions (plane parallel) make any overall difference (that is, they can't make the net refraction opposite in sign from the standard refraction); if the atmospheric density is plane-parallel, the net refraction always puts the apparent stars above the "true" stars.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"So the net refraction (standard plus the weather front) is 4" of arc TOWARDS the zenith on one side of the zenith and 2" of arc AWAY from the zenith on the other side.
Make sense?"
Did that resolve the matter for everyone, or no? John B, does that make sense for you? You asked for a specific example (but that post more or less coincided in time with the above example so you may have missed the details). The conclusion is YES, the net refraction CAN place a star's apparent position lower in the sky than its true position, but rarely and not by much.
By the way, I don't think temperature inversions (plane parallel) make any overall difference (that is, they can't make the net refraction opposite in sign from the standard refraction); if the atmospheric density is plane-parallel, the net refraction always puts the apparent stars above the "true" stars.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
