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Re: 2005 Nautical Almanac refraction table
From: Marcel Tschudin
Date: 2005 Aug 29, 21:22 +0300
From: Marcel Tschudin
Date: 2005 Aug 29, 21:22 +0300
Fred, you wrote refering to the question regarding standard conditions of the Nautical Almanac: > Whatever are the standard conditions for the Nautical Almanac, which I > don't have here at work. As I recall it's about 29.9 inches of mercury > for air pressure and about 50 F for air temperature. I was finally able to find the answer on a page in Google's cache: quote Altitude Corrections -- Enter the tables at the front and back of the Nautical Almanac with ha to find the total Altitude Correction for all three of: 1.. R = atmospheric refraction; correction owing to varying atmospheric density with altitude, always minus (all bodies), ...... The standard refraction corrections are based on 10oC, 1010 mb, humidity 80% and wavelength 0.50169 micrometers. The Main Altitude Correction accounts for general atmospheric refraction, but an Additional Refraction correction can also be made to account for local temperature and barometric pressure when hs is very low (< 10o), or when conditions are significantly different from the standard mean refraction values for 10oC and 1010 mb: see table A4 Almanac. The Almanac's mean refraction also includes humidity 80% and wavelength 0.50169 micrometers. unquote 1010mb coerresponding to 29.83 inch of mercuy 10degC corresponding to 50degF Congratulations, Fred, for your memory! Marcel