Calculation of sunrise and sunset
From WickyWiki
Source:
- https://www.esrl.noaa.gov/gmd/grad/solcalc/
- https://www.esrl.noaa.gov/gmd/grad/solcalc/solareqns.PDF
Input example:
- Date --> vDayOfYear
- Date --> vLeapyear
Fractional year (radians)
vY = 2 * PI() / (365 + vLeapYear) * (vDayOfYear - 1 )
Equation of time (minutes)
vEqtime = 229.18 * (0.000075 + 0.001868 * COS( vY ) - 0.032077 * SIN( vY ) - 0.014615 * COS(2 * vY ) - 0.040849 * SIN(2 * vY )
Solar declination angle (radians).
vDecl = 0.006918 - 0.399912 * COS(vY) + 0.070257 * SIN(vY) - 0.006758 * COS(2 * vY) + 0.000907 * SIN(2 * vY) - 0.002697 * COS(3 * vY) + 0.00148 * SIN (3 * vY)
For sunrise or sunset, the zenith is set to 90.833 degrees (the approximate correction for atmospheric refraction at sunrise and sunset, and the size of the solar disk). Hours angle (radians):
vHa = ACOS( COS( TO_RADIANS(90.833) ) / COS(vLat) * COS(vDecl) - TAN(vLat) * TAN(vDecl) )
Sunrise UTC minutes
vUtcMinsSunrise = 360 * 2 - 4 * (vLon + TO_DEGREES(vHa) ) - vEqtime
Noon UTC minutes
vUtcMinsNoon = 360 * 2 - 4 * vLon - vEqtime
Sunset UTC minutes
vUtcMinsSunset = 360 * 2 - 4 * (vLon - TO_DEGREES(vHa) ) - vEqtime
Sunset local time in fractional day. For Europe/Amsterdam --> vTimezone=+1 or +2 (DST)
(vUtcMinsSunset / 60 + vTimezone) / 24
