/** Returns true, if the sun is up all day (no rise and set). */
private boolean isSunUpAllDay(Calendar calendar, double latitude, double longitude) {
Calendar cal = DateTimeUtils.truncateToMidnight(calendar);
Sun sun = new Sun();
for (int minutes = 0; minutes <= MINUTES_PER_DAY; minutes += CURVE_TIME_INTERVAL) {
setSunPosition(calendar, latitude, longitude, sun);
if (sun.getPosition().getElevation() < SUN_ANGLE) {
return false;
}
cal.add(Calendar.MINUTE, CURVE_TIME_INTERVAL);
}
return true;
}
/** Calculates the sun position (azimuth and elevation). */
public void setSunPosition(Calendar calendar, double latitude, double longitude, Sun sun) {
double lw = -longitude * DEG2RAD;
double phi = latitude * DEG2RAD;
double j = DateTimeUtils.dateToJulianDate(calendar);
double m = getSolarMeanAnomaly(j);
double c = getEquationOfCenter(m);
double lsun = getEclipticLongitude(m, c);
double d = getSunDeclination(lsun);
double a = getRightAscension(lsun);
double th = getSiderealTime(j, lw);
double azimuth = getAzimuth(th, a, phi, d) / DEG2RAD;
double elevation = getElevation(th, a, phi, d) / DEG2RAD;
Position position = sun.getPosition();
position.setAzimuth(azimuth + 180);
position.setElevation(elevation);
}
private Sun getSunInfo(Calendar calendar, double latitude, double longitude, boolean onlyAstro) {
double lw = -longitude * DEG2RAD;
double phi = latitude * DEG2RAD;
double j = DateTimeUtils.midnightDateToJulianDate(calendar) + 0.5;
double n = getJulianCycle(j, lw);
double js = getApproxSolarTransit(0, lw, n);
double m = getSolarMeanAnomaly(js);
double c = getEquationOfCenter(m);
double lsun = getEclipticLongitude(m, c);
double d = getSunDeclination(lsun);
double jtransit = getSolarTransit(js, m, lsun);
double w0 = getHourAngle(H0, phi, d);
double w1 = getHourAngle(H0 + SUN_DIAMETER, phi, d);
double jset = getSunsetJulianDate(w0, m, lsun, lw, n);
double jsetstart = getSunsetJulianDate(w1, m, lsun, lw, n);
double jrise = getSunriseJulianDate(jtransit, jset);
double jriseend = getSunriseJulianDate(jtransit, jsetstart);
double w2 = getHourAngle(H1, phi, d);
double jnau = getSunsetJulianDate(w2, m, lsun, lw, n);
double Jciv2 = getSunriseJulianDate(jtransit, jnau);
double w3 = getHourAngle(H2, phi, d);
double w4 = getHourAngle(H3, phi, d);
double jastro = getSunsetJulianDate(w3, m, lsun, lw, n);
double jdark = getSunsetJulianDate(w4, m, lsun, lw, n);
double jnau2 = getSunriseJulianDate(jtransit, jastro);
double jastro2 = getSunriseJulianDate(jtransit, jdark);
Sun sun = new Sun();
sun.setAstroDawn(new Range(DateTimeUtils.toCalendar(jastro2), DateTimeUtils.toCalendar(jnau2)));
sun.setAstroDusk(new Range(DateTimeUtils.toCalendar(jastro), DateTimeUtils.toCalendar(jdark)));
if (onlyAstro) {
return sun;
}
sun.setNoon(
new Range(
DateTimeUtils.toCalendar(jtransit),
DateTimeUtils.toCalendar(jtransit + JD_ONE_MINUTE_FRACTION)));
sun.setRise(new Range(DateTimeUtils.toCalendar(jrise), DateTimeUtils.toCalendar(jriseend)));
sun.setSet(new Range(DateTimeUtils.toCalendar(jsetstart), DateTimeUtils.toCalendar(jset)));
sun.setCivilDawn(new Range(DateTimeUtils.toCalendar(Jciv2), DateTimeUtils.toCalendar(jrise)));
sun.setCivilDusk(new Range(DateTimeUtils.toCalendar(jset), DateTimeUtils.toCalendar(jnau)));
sun.setNauticDawn(new Range(DateTimeUtils.toCalendar(jnau2), DateTimeUtils.toCalendar(Jciv2)));
sun.setNauticDusk(new Range(DateTimeUtils.toCalendar(jnau), DateTimeUtils.toCalendar(jastro)));
boolean isSunUpAllDay = isSunUpAllDay(calendar, latitude, longitude);
// daylight
Range daylightRange = new Range();
if (sun.getRise().getStart() == null && sun.getRise().getEnd() == null) {
if (isSunUpAllDay) {
daylightRange =
new Range(
DateTimeUtils.truncateToMidnight(calendar),
DateTimeUtils.truncateToMidnight(addDays(calendar, 1)));
}
} else {
daylightRange = new Range(sun.getRise().getEnd(), sun.getSet().getStart());
}
sun.setDaylight(daylightRange);
// morning night
Sun sunYesterday = getSunInfo(addDays(calendar, -1), latitude, longitude, true);
Range morningNightRange = null;
if (sunYesterday.getAstroDusk().getEnd() != null
&& DateUtils.isSameDay(sunYesterday.getAstroDusk().getEnd(), calendar)) {
morningNightRange =
new Range(sunYesterday.getAstroDusk().getEnd(), sun.getAstroDawn().getStart());
} else if (isSunUpAllDay) {
morningNightRange = new Range();
} else {
morningNightRange =
new Range(DateTimeUtils.truncateToMidnight(calendar), sun.getAstroDawn().getStart());
}
sun.setMorningNight(morningNightRange);
// evening night
Range eveningNightRange = null;
if (sun.getAstroDusk().getEnd() != null
&& DateUtils.isSameDay(sun.getAstroDusk().getEnd(), calendar)) {
eveningNightRange =
new Range(
sun.getAstroDusk().getEnd(), DateTimeUtils.truncateToMidnight(addDays(calendar, 1)));
} else {
eveningNightRange = new Range();
}
sun.setEveningNight(eveningNightRange);
// night
if (isSunUpAllDay) {
sun.setNight(new Range());
} else {
Sun sunTomorrow = getSunInfo(addDays(calendar, 1), latitude, longitude, true);
sun.setNight(new Range(sun.getAstroDusk().getEnd(), sunTomorrow.getAstroDawn().getStart()));
}
// eclipse
SunEclipse eclipse = sun.getEclipse();
MoonCalc mc = new MoonCalc();
double partial =
mc.getEclipse(calendar, MoonCalc.ECLIPSE_TYPE_SUN, j, MoonCalc.ECLIPSE_MODE_PARTIAL);
eclipse.setPartial(DateTimeUtils.toCalendar(partial));
double ring = mc.getEclipse(calendar, MoonCalc.ECLIPSE_TYPE_SUN, j, MoonCalc.ECLIPSE_MODE_RING);
eclipse.setRing(DateTimeUtils.toCalendar(ring));
double total =
mc.getEclipse(calendar, MoonCalc.ECLIPSE_TYPE_SUN, j, MoonCalc.ECLIPSE_MODE_TOTAL);
eclipse.setTotal(DateTimeUtils.toCalendar(total));
return sun;
}