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A NEW TABLE AND APPROXIMATION FORMULA FOR THE RELATIVE OPTICAL AIR MASS,
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER N H
A table is presented which is computed from the air density profile of the ARDC Model Atmosphere, 1959, up to 84 km height n sub 0 1.000276 is taken corresponding to air of 15C and 1013.25 mb ground level values of the ARDC Model Atmosphere, 1959 and to the wavelength 0.7 mu. This wavelength is more representative for the whole solar spectrum than 0.54 mu because it divides the solar spectrum into two parts of equal energy. A new approximation formula for the relative optical air mass m as function of solar altitude gamma deg is presented also. The values of the relative optical air mass calculated from the approximation formula are in very good agreement with the tabulated values. The deviation is less than 0.1 for gamma 4 deg. The highest deviation, 1.25, occurs at gamma 0.5 deg. The approximation formula can be applied as well to the old Bemporad table and to the table of the relative optical water vapor mass computed by Schnaidt 1938 then the constants have the values a 0.6556, b 6.379, c 1.757, and a 0.0548, b 2.650, c 1.452, respectively.