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Title: A new table and approximation formula for the relative optical air mass
Authors: Kasten, Fritz.
Keywords: Solar radiation
Mathematical analysis
Mathematical models
Mathematical tables
Atmospheric optics
Optical properties
Air masses
Issue Date: Nov-1964
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (Cold Regions Research and Engineering Laboratory (U.S.)) ; 136.
Description: Technical Report
Summary: A new table of the relative optical air mass as a function of solar altitude is computed from the air density profile of the ARDC Model Atmosphere, 1959, up to 84 km ; refractive index of air at ground level equal to 1.000276 corresponds to air of 15°C and 1013.25 mb and to the wavelength 0.7 micron. This wavelength is more representative for the whole solar spectrum than 0.54 micro (peak of the visibility spectrum) because it divides the solar spectrum into 2 parts of equal energy. The new appoximation formula contains constants which were calculated from the new tabulated values of the relative optical air mass as a function of solar altitude [deg] by successive approximation, applying the method of least squares to obtain each approximation. The values from this formula are in very good agreement with the tabulated values. The deviation is less than 0.1 percent for solar altitude greater than 4 deg. The highest deviation, 1.25 percent, occurs at solar altitude equal to 0.5 deg. The formula can also be applied to the old Bemporad table and to the table of relative optical water vapor mass computed by Schnaidt (1938).
Appears in Collections:CRREL Technical Report

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