/* This macro computes the length of the day, from sunrise to sunset. */ /* Sunrise/set is considered to occur when the Sun's upper limb is */ /* 35 arc minutes below the horizon (this accounts for the refraction */ /* of the Earth's atmosphere). */ #define day_length(year,month,day,lon,lat) \ __daylen__( year, month, day, lon, lat, -35.0/60.0, 1 ) /* This macro computes the length of the day, including civil twilight. */ /* Civil twilight starts/ends when the Sun's center is 6 degrees below */ /* the horizon. */ #define day_civil_twilight_length(year,month,day,lon,lat) \ __daylen__( year, month, day, lon, lat, -6.0, 0 ) /* This macro computes the length of the day, incl. nautical twilight. */ /* Nautical twilight starts/ends when the Sun's center is 12 degrees */ /* below the horizon. */ #define day_nautical_twilight_length(year,month,day,lon,lat) \ __daylen__( year, month, day, lon, lat, -12.0, 0 ) /* This macro computes the length of the day, incl. astronomical twilight. */ /* Astronomical twilight starts/ends when the Sun's center is 18 degrees */ /* below the horizon. */ #define day_astronomical_twilight_length(year,month,day,lon,lat) \ __daylen__( year, month, day, lon, lat, -18.0, 0 ) /* This macro computes times for sunrise/sunset. */ /* Sunrise/set is considered to occur when the Sun's upper limb is */ /* 35 arc minutes below the horizon (this accounts for the refraction */ /* of the Earth's atmosphere). */ #define timelib_astro_sun_rise_set(ts,lon,lat,hrise,hset,rise,set) \ timelib_astro_rise_set_altitude( ts, lon, lat, -35.0/60.0, 1, hrise, hset, rise, set ) /* This macro computes the start and end times of civil twilight. */ /* Civil twilight starts/ends when the Sun's center is 6 degrees below */ /* the horizon. */ #define civil_twilight(ts,lon,lat,start,end) \ timelib_astro_rise_set_altitude( ts, lon, lat, -6.0, 0, start, end ) /* This macro computes the start and end times of nautical twilight. */ /* Nautical twilight starts/ends when the Sun's center is 12 degrees */ /* below the horizon. */ #define nautical_twilight(ts,lon,lat,start,end) \ timelib_astro_rise_set_altitude( ts, lon, lat, -12.0, 0, start, end ) /* This macro computes the start and end times of astronomical twilight. */ /* Astronomical twilight starts/ends when the Sun's center is 18 degrees */ /* below the horizon. */ #define astronomical_twilight(ts,lon,lat,start,end) \ timelib_astro_rise_set_altitude( ts, lon, lat, -18.0, 0, start, end )