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    Re: 2005 Nautical Almanac refraction table
    From: Marcel Tschudin
    Date: 2005 Aug 29, 21:22 +0300

    Fred, you wrote refering to the question regarding standard conditions of
    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:
    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
      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.
    1010mb coerresponding to 29.83 inch of mercuy
    10degC corresponding to 50degF
    Congratulations, Fred, for your memory!

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