1 /* This macro computes the length of the day, from sunrise to sunset. */ 2 /* Sunrise/set is considered to occur when the Sun's upper limb is */ 3 /* 35 arc minutes below the horizon (this accounts for the refraction */ 4 /* of the Earth's atmosphere). */ 5 #define day_length(year,month,day,lon,lat) \ 6 __daylen__( year, month, day, lon, lat, -35.0/60.0, 1 ) 7 8 /* This macro computes the length of the day, including civil twilight. */ 9 /* Civil twilight starts/ends when the Sun's center is 6 degrees below */ 10 /* the horizon. */ 11 #define day_civil_twilight_length(year,month,day,lon,lat) \ 12 __daylen__( year, month, day, lon, lat, -6.0, 0 ) 13 14 /* This macro computes the length of the day, incl. nautical twilight. */ 15 /* Nautical twilight starts/ends when the Sun's center is 12 degrees */ 16 /* below the horizon. */ 17 #define day_nautical_twilight_length(year,month,day,lon,lat) \ 18 __daylen__( year, month, day, lon, lat, -12.0, 0 ) 19 20 /* This macro computes the length of the day, incl. astronomical twilight. */ 21 /* Astronomical twilight starts/ends when the Sun's center is 18 degrees */ 22 /* below the horizon. */ 23 #define day_astronomical_twilight_length(year,month,day,lon,lat) \ 24 __daylen__( year, month, day, lon, lat, -18.0, 0 ) 25 26 27 /* This macro computes times for sunrise/sunset. */ 28 /* Sunrise/set is considered to occur when the Sun's upper limb is */ 29 /* 35 arc minutes below the horizon (this accounts for the refraction */ 30 /* of the Earth's atmosphere). */ 31 #define timelib_astro_sun_rise_set(ts,lon,lat,hrise,hset,rise,set) \ 32 timelib_astro_rise_set_altitude( ts, lon, lat, -35.0/60.0, 1, hrise, hset, rise, set ) 33 34 /* This macro computes the start and end times of civil twilight. */ 35 /* Civil twilight starts/ends when the Sun's center is 6 degrees below */ 36 /* the horizon. */ 37 #define civil_twilight(ts,lon,lat,start,end) \ 38 timelib_astro_rise_set_altitude( ts, lon, lat, -6.0, 0, start, end ) 39 40 /* This macro computes the start and end times of nautical twilight. */ 41 /* Nautical twilight starts/ends when the Sun's center is 12 degrees */ 42 /* below the horizon. */ 43 #define nautical_twilight(ts,lon,lat,start,end) \ 44 timelib_astro_rise_set_altitude( ts, lon, lat, -12.0, 0, start, end ) 45 46 /* This macro computes the start and end times of astronomical twilight. */ 47 /* Astronomical twilight starts/ends when the Sun's center is 18 degrees */ 48 /* below the horizon. */ 49 #define astronomical_twilight(ts,lon,lat,start,end) \ 50 timelib_astro_rise_set_altitude( ts, lon, lat, -18.0, 0, start, end ) 51 52
