sunrise2.html

日出日落计算程序的网页源代码 从网络上搜索到的

	}


//***********************************************************************/
//* Name:    calcTimeJulianCent							*/
//* Type:    Function									*/
//* Purpose: convert Julian Day to centuries since J2000.0.			*/
//* Arguments:										*/
//*   jd : the Julian Day to convert						*/
//* Return value:										*/
//*   the T value corresponding to the Julian Day				*/
//***********************************************************************/

	function calcTimeJulianCent(jd)
	{
		var T = (jd - 2451545.0)/36525.0;
		return T;
	}


//***********************************************************************/
//* Name:    calcJDFromJulianCent							*/
//* Type:    Function									*/
//* Purpose: convert centuries since J2000.0 to Julian Day.			*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   the Julian Day corresponding to the t value				*/
//***********************************************************************/

	function calcJDFromJulianCent(t)
	{
		var JD = t * 36525.0 + 2451545.0;
		return JD;
	}


//***********************************************************************/
//* Name:    calGeomMeanLongSun							*/
//* Type:    Function									*/
//* Purpose: calculate the Geometric Mean Longitude of the Sun		*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   the Geometric Mean Longitude of the Sun in degrees			*/
//***********************************************************************/

	function calcGeomMeanLongSun(t)
	{
		var L0 = 280.46646 + t * (36000.76983 + 0.0003032 * t);
		while(L0 > 360.0)
		{
			L0 -= 360.0;
		}
		while(L0 < 0.0)
		{
			L0 += 360.0;
		}
		return L0;		// in degrees
	}


//***********************************************************************/
//* Name:    calGeomAnomalySun							*/
//* Type:    Function									*/
//* Purpose: calculate the Geometric Mean Anomaly of the Sun		*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   the Geometric Mean Anomaly of the Sun in degrees			*/
//***********************************************************************/

	function calcGeomMeanAnomalySun(t)
	{
		var M = 357.52911 + t * (35999.05029 - 0.0001537 * t);
		return M;		// in degrees
	}

//***********************************************************************/
//* Name:    calcEccentricityEarthOrbit						*/
//* Type:    Function									*/
//* Purpose: calculate the eccentricity of earth's orbit			*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   the unitless eccentricity							*/
//***********************************************************************/


	function calcEccentricityEarthOrbit(t)
	{
		var e = 0.016708634 - t * (0.000042037 + 0.0000001267 * t);
		return e;		// unitless
	}

//***********************************************************************/
//* Name:    calcSunEqOfCenter							*/
//* Type:    Function									*/
//* Purpose: calculate the equation of center for the sun			*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   in degrees										*/
//***********************************************************************/


	function calcSunEqOfCenter(t)
	{
		var m = calcGeomMeanAnomalySun(t);

		var mrad = degToRad(m);
		var sinm = Math.sin(mrad);
		var sin2m = Math.sin(mrad+mrad);
		var sin3m = Math.sin(mrad+mrad+mrad);

		var C = sinm * (1.914602 - t * (0.004817 + 0.000014 * t)) + sin2m * (0.019993 - 0.000101 * t) + sin3m * 0.000289;
		return C;		// in degrees
	}

//***********************************************************************/
//* Name:    calcSunTrueLong								*/
//* Type:    Function									*/
//* Purpose: calculate the true longitude of the sun				*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun's true longitude in degrees						*/
//***********************************************************************/


	function calcSunTrueLong(t)
	{
		var l0 = calcGeomMeanLongSun(t);
		var c = calcSunEqOfCenter(t);

		var O = l0 + c;
		return O;		// in degrees
	}

//***********************************************************************/
//* Name:    calcSunTrueAnomaly							*/
//* Type:    Function									*/
//* Purpose: calculate the true anamoly of the sun				*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun's true anamoly in degrees							*/
//***********************************************************************/

	function calcSunTrueAnomaly(t)
	{
		var m = calcGeomMeanAnomalySun(t);
		var c = calcSunEqOfCenter(t);

		var v = m + c;
		return v;		// in degrees
	}

//***********************************************************************/
//* Name:    calcSunRadVector								*/
//* Type:    Function									*/
//* Purpose: calculate the distance to the sun in AU				*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun radius vector in AUs							*/
//***********************************************************************/

	function calcSunRadVector(t)
	{
		var v = calcSunTrueAnomaly(t);
		var e = calcEccentricityEarthOrbit(t);
 
		var R = (1.000001018 * (1 - e * e)) / (1 + e * Math.cos(degToRad(v)));
		return R;		// in AUs
	}

//***********************************************************************/
//* Name:    calcSunApparentLong							*/
//* Type:    Function									*/
//* Purpose: calculate the apparent longitude of the sun			*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun's apparent longitude in degrees						*/
//***********************************************************************/

	function calcSunApparentLong(t)
	{
		var o = calcSunTrueLong(t);

		var omega = 125.04 - 1934.136 * t;
		var lambda = o - 0.00569 - 0.00478 * Math.sin(degToRad(omega));
		return lambda;		// in degrees
	}

//***********************************************************************/
//* Name:    calcMeanObliquityOfEcliptic						*/
//* Type:    Function									*/
//* Purpose: calculate the mean obliquity of the ecliptic			*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   mean obliquity in degrees							*/
//***********************************************************************/

	function calcMeanObliquityOfEcliptic(t)
	{
		var seconds = 21.448 - t*(46.8150 + t*(0.00059 - t*(0.001813)));
		var e0 = 23.0 + (26.0 + (seconds/60.0))/60.0;
		return e0;		// in degrees
	}

//***********************************************************************/
//* Name:    calcObliquityCorrection						*/
//* Type:    Function									*/
//* Purpose: calculate the corrected obliquity of the ecliptic		*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   corrected obliquity in degrees						*/
//***********************************************************************/

	function calcObliquityCorrection(t)
	{
		var e0 = calcMeanObliquityOfEcliptic(t);

		var omega = 125.04 - 1934.136 * t;
		var e = e0 + 0.00256 * Math.cos(degToRad(omega));
		return e;		// in degrees
	}

//***********************************************************************/
//* Name:    calcSunRtAscension							*/
//* Type:    Function									*/
//* Purpose: calculate the right ascension of the sun				*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun's right ascension in degrees						*/
//***********************************************************************/

	function calcSunRtAscension(t)
	{
		var e = calcObliquityCorrection(t);
		var lambda = calcSunApparentLong(t);
 
		var tananum = (Math.cos(degToRad(e)) * Math.sin(degToRad(lambda)));
		var tanadenom = (Math.cos(degToRad(lambda)));
		var alpha = radToDeg(Math.atan2(tananum, tanadenom));
		return alpha;		// in degrees
	}

//***********************************************************************/
//* Name:    calcSunDeclination							*/
//* Type:    Function									*/
//* Purpose: calculate the declination of the sun				*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   sun's declination in degrees							*/
//***********************************************************************/

	function calcSunDeclination(t)
	{
		var e = calcObliquityCorrection(t);
		var lambda = calcSunApparentLong(t);

		var sint = Math.sin(degToRad(e)) * Math.sin(degToRad(lambda));
		var theta = radToDeg(Math.asin(sint));
		return theta;		// in degrees
	}

//***********************************************************************/
//* Name:    calcEquationOfTime							*/
//* Type:    Function									*/
//* Purpose: calculate the difference between true solar time and mean	*/
//*		solar time									*/
//* Arguments:										*/
//*   t : number of Julian centuries since J2000.0				*/
//* Return value:										*/
//*   equation of time in minutes of time						*/
//***********************************************************************/

	function calcEquationOfTime(t)
	{
		var epsilon = calcObliquityCorrection(t);
		var l0 = calcGeomMeanLongSun(t);
		var e = calcEccentricityEarthOrbit(t);
		var m = calcGeomMeanAnomalySun(t);

		var y = Math.tan(degToRad(epsilon)/2.0);
		y *= y;

		var sin2l0 = Math.sin(2.0 * degToRad(l0));
		var sinm   = Math.sin(degToRad(m));
		var cos2l0 = Math.cos(2.0 * degToRad(l0));
		var sin4l0 = Math.sin(4.0 * degToRad(l0));
		var sin2m  = Math.sin(2.0 * degToRad(m));

		var Etime = y * sin2l0 - 2.0 * e * sinm + 4.0 * e * y * sinm * cos2l0
				- 0.5 * y * y * sin4l0 - 1.25 * e * e * sin2m;

		return radToDeg(Etime)*4.0;	// in minutes of time
	}

//***********************************************************************/
//* Name:    calcHourAngleSunrise							*/
//* Type:    Function									*/
//* Purpose: calculate the hour angle of the sun at sunrise for the	*/
//*			latitude								*/
//* Arguments:										*/
//*   lat : latitude of observer in degrees					*/
//*	solarDec : declination angle of sun in degrees				*/
//* Return value:										*/
//*   hour angle of sunrise in radians						*/
//***********************************************************************/

	function calcHourAngleSunrise(lat, solarDec)
	{
		var latRad = degToRad(lat);
		var sdRad  = degToRad(solarDec)

		var HAarg = (Math.cos(degToRad(90.833))/(Math.cos(latRad)*Math.cos(sdRad))-Math.tan(latRad) * Math.tan(sdRad));

		var HA = (Math.acos(Math.cos(degToRad(90.833))/(Math.cos(latRad)*Math.cos(sdRad))-Math.tan(latRad) * Math.tan(sdRad)));

		return HA;		// in radians
	}

//***********************************************************************/
//* Name:    calcHourAngleSunset							*/
//* Type:    Function									*/
//* Purpose: calculate the hour angle of the sun at sunset for the	*/
//*			latitude								*/
//* Arguments:										*/
//*   lat : latitude of observer in degrees					*/
//*	solarDec : declination angle of sun in degrees				*/
//* Return value:										*/
//*   hour angle of sunset in radians						*/
//***********************************************************************/

	function calcHourAngleSunset(lat, solarDec)
	{
		var latRad = degToRad(lat);
		var sdRad  = degToRad(solarDec)

		var HAarg = (Math.cos(degToRad(90.833))/(Math.cos(latRad)*Math.cos(sdRad))-Math.tan(latRad) * Math.tan(sdRad));

		var HA = (Math.acos(Math.cos(degToRad(90.833))/(Math.cos(latRad)*Math.cos(sdRad))-Math.tan(latRad) * Math.tan(sdRad)));

		return -HA;		// in radians
	}


//***********************************************************************/
//* Name:    calcSunriseUTC								*/
//* Type:    Function									*/
//* Purpose: calculate the Universal Coordinated Time (UTC) of sunrise	*/
//*			for the given day at the given location on earth	*/
//* Arguments:										*/
//*   JD  : julian day									*/
//*   latitude : latitude of observer in degrees				*/
//*   longitude : longitude of observer in degrees				*/
//* Return value:										*/
//*   time in minutes from zero Z							*/
//***********************************************************************/

	function calcSunriseUTC(JD, latitude, longitude)
	{
		var t = calcTimeJulianCent(JD);

		// *** Find the time of solar noon at the location, and use
        //     that declination. This is better than start of the 
        //     Julian day

		var noonmin = calcSolNoonUTC(t, longitude);
		var tnoon = calcTimeJulianCent (JD+noonmin/1440.0);

		// *** First pass to approximate sunrise (using solar noon)

		var eqTime = calcEquationOfTime(tnoon);
		var solarDec = calcSunDeclination(tnoon);
		var hourAngle = calcHourAngleSunrise(latitude, solarDec);

		var delta = longitude - radToDeg(hourAngle);
		var timeDiff = 4 * delta;	// in minutes of time
		var timeUTC = 720 + timeDiff - eqTime;	// in minutes

		// alert("eqTime = " + eqTime + "\nsolarDec = " + solarDec + "\ntimeUTC = " + timeUTC);