This web page produces a numerical table of sunrise, sunset,
daily insolation at top of atmosphere, and sunlight-weighted cosine of
the zenith angle at a single specified location. The produced table
contains data for a single month, or if a month is not provided, data
for a single calendar year. Latitude and longitude must be given in
degrees and hundredths of degrees, not degrees and minutes. Default
location is the Central Park weather station, New York City.
As explained in the file
SRERROR.TXT, the Atmosphere-Ocean Model
assumes that the Sun is a point source. The columns for daily
insolation (sunlight)
and mean zenith angle in the produced table continue to use this
assumption. The maximum error for this assumption occurs at the poles
during the equinoxes where the table's algorithm would indicate no
insolation but in reality there should be about x.xx (W/mē). The
columns for sunrise and sunset, however, do consider the radius of the
Sun's disk as seen from the Earth (0.267° on average) and atmospheric
refraction of sunlight (approximately 0.583° on the horizon). The
table should be accurate to within one minute. During equinoxes,
points on the equator see about 12 hours and 7 minutes of daylight.
The 7 minutes are due to the radius of the Sun's disk and atmospheric
refraction.
SRLOCAT.FOR is the Fortran source code of
the program used on this web page.
