LEVELS OF NOCTURNAL ILLUMINATION
INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA RESEARCH AND ENGINEERING SUPPORT DIV
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Summary tables show, for four lunar months mid-summer, mid-fall, mid-winter, and mid-spring, the number of hours in which the illumination exceeds levels in 8 decades from 1.5 x 0.000001 lumens per square foot to 1.5 x 101 lumens per square foot the full tables list the hours, day by day, in which the illumination exceeds the same 8 levels. Note that the sum of the hours not exceeding and the hours exceeding a given level equals a constant which is the total number of hours in a lunar month. So that these tables may be more easily understood, they also have been plotted at levels of 1.5 x 0. 00001, 1.5 x 0.001, 1.5 x 0.1, and 1.5 x 101. These curves show the number of hours per day as a function of date, the time that terrestrial illumination equals or exceeds these values. There are separate sets of tables for latitudes of 0 degree, 30 degrees, and 60 degrees latitude.
- Atmospheric Physics