Solar Calculator

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Equation of Time:
Solar Declination:
Apparent Sunrise:
Apparent Solar Noon:
Apparent Sunset:

Apparent Sunrise UTC:
Apparent Solar Noon UTC:
Apparent Sunset UTC:

var solarRiseSet = new Array();
solarRiseSet.sunrise = “”;
solarRiseSet.utcSunrise = “”;
solarRiseSet.sunset = “”;
solarRiseSet.utcSunset = “”;
solarRiseSet.solnoon = “”;
solarRiseSet.utcSolnoon = “”;
solarRiseSet.eqTime = “”;
solarRiseSet.solarDec = “”;
solarRiseSet.dbug = “”;

/**
* Global input variables
*/
var solarDateTimeLatLong = new Array();
solarDateTimeLatLong.latDeg = “”;
solarDateTimeLatLong.latMin = “”;
solarDateTimeLatLong.latSec = “”;
solarDateTimeLatLong.lonDeg = “”;
solarDateTimeLatLong.lonMin = “”;
solarDateTimeLatLong.lonSec = “”;
solarDateTimeLatLong.hrsToGMT = “”;
solarDateTimeLatLong.mos = “”; // January = 0, December = 11
solarDateTimeLatLong.day = “”;
solarDateTimeLatLong.year = “”;
solarDateTimeLatLong.daySavings = “”; // = 0 (no) or 60 (yes)

/**
* List of months and days (for non-leap years) used by isValidInput, calcDateFromJD, and calcDayFromJD
*/
var monthList = new Array();
var i = 0;
monthList[i++] = new month(“January”, 31, “Jan”);
monthList[i++] = new month(“February”, 28, “Feb”);
monthList[i++] = new month(“March”, 31, “Mar”);
monthList[i++] = new month(“April”, 30, “Apr”);
monthList[i++] = new month(“May”, 31, “May”);
monthList[i++] = new month(“June”, 30, “Jun”);
monthList[i++] = new month(“July”, 31, “Jul”);
monthList[i++] = new month(“August”, 31, “Aug”);
monthList[i++] = new month(“September”, 30, “Sep”);
monthList[i++] = new month(“October”, 31, “Oct”);
monthList[i++] = new month(“November”, 30, “Nov”);
monthList[i++] = new month(“December”, 31, “Dec”);

function month(name, numdays, abbr) {
this.name = name;
this.numdays = numdays;
this.abbr = abbr;
}

/**
* Returns 1 if the 4-digit yr is a leap year, 0 if it is not
*/
function isLeapYear(yr) {
return ((yr % 4 == 0 && yr % 100 != 0) || yr % 400 == 0);
}

/**
* isPosInteger returns false if the value is not a positive integer, true is returned otherwise. The code is from taken from Danny Goodman’s Javascript Handbook, p. 372.
*/
function isPosInteger(inputVal) {
inputStr = (“” + inputVal);
for (var i = 0; i < inputStr.length; i++) {
var oneChar = inputStr.charAt(i);
if (oneChar < “0” || oneChar > “9”)
return false;
}
return true;
}

/**
* isValidInput makes sure valid input is entered before going ahead to calculate the sunrise and sunset.
* False is returned if an invalid entry was made, true if the entry is valid.
*/
function isValidInput(index) {
if (solarDateTimeLatLong.day == “”) { // see if the day field is empty
alert(“You must enter a day before attempting the calculation.”);
return false;
}
else if (solarDateTimeLatLong.year == “”) { // see if the year field is empty
alert(“You must enter a year before attempting the calculation.”);
return false;
}
else if (!isPosInteger(solarDateTimeLatLong.day) || solarDateTimeLatLong.day == 0) {
alert(“The day must be a positive integer.”);
return false;
}
else if (!isInteger(solarDateTimeLatLong.year)) {
alert(“The year must be an integer.”);
return false;
}
else if ((solarDateTimeLatLong.year < -1000) || (solarDateTimeLatLong.year > 3000)) {
alert(“The algorithm used is not valid for years outside of/nthe range -1000 to 3000.”);
return false;
}
// For the non-February months see if the day entered is greater than the number of days in the selected month
else if ((index != 1) && (solarDateTimeLatLong.day > monthList[index].numdays)) {
alert(“There are only ” + monthList[index].numdays + ” days in ” + monthList[index].name + “.”);
return false;
}
// First see if the year entered is a leap year. If so we have to make sure the days entered is <= 29. If not a leap year we make sure that the days entered is <= 28. else if (index == 1) { // month selected is February the screwball month if (isLeapYear(solarDateTimeLatLong.year)) { // year entered is a leap year if (solarDateTimeLatLong.day > (monthList[index].numdays + 1)) {
alert(“There are only ” + (monthList[index].numdays + 1) + ” days in ” + monthList[index].name + “.”);
return false;
}
else
return true;
}
else { // year entered is not a leap year
if (solarDateTimeLatLong.day > monthList[index].numdays) {
alert(“There are only ” + monthList[index].numdays + ” days in ” + monthList[index].name + “.”);
return false;
}
else
return true;
}
}
else
return true;
}

/**
* Converts any type of lat/long input into the table form and then handles bad input
* Nested in the calcSun function.
*/
function convLatLong(f) {
if(solarDateTimeLatLong.latDeg == “”) {
solarDateTimeLatLong.latDeg = 0;
}
if(solarDateTimeLatLong.latMin == “”) {
solarDateTimeLatLong.latMin = 0;
}
if(solarDateTimeLatLong.latSec == “”) {
solarDateTimeLatLong.latSec = 0;
}
if(solarDateTimeLatLong.lonDeg == “”) {
solarDateTimeLatLong.lonDeg = 0;
}
if(solarDateTimeLatLong.lonMin == “”) {
solarDateTimeLatLong.lonMin = 0;
}
if(solarDateTimeLatLong.lonSec == “”) {
solarDateTimeLatLong.lonSec = 0;
}
var neg = 0;
if(solarDateTimeLatLong.latDeg.charAt(0) == ‘-‘) {
neg = 1;
}
if(neg != 1) {
var latSeconds = (parseFloat(solarDateTimeLatLong.latDeg))*3600 + parseFloat(solarDateTimeLatLong.latMin)*60 + parseFloat(solarDateTimeLatLong.latSec)*1;
solarDateTimeLatLong.latDeg = Math.floor(latSeconds/3600);
solarDateTimeLatLong.latMin = Math.floor((latSeconds – (parseFloat(solarDateTimeLatLong.latDeg)*3600))/60);
solarDateTimeLatLong.latSec = Math.floor((latSeconds – (parseFloat(solarDateTimeLatLong.latDeg)*3600) – (parseFloat(solarDateTimeLatLong.latMin)*60)) + 0.5);
}
else if(parseFloat(solarDateTimeLatLong.latDeg) > -1) {
var latSeconds = parseFloat(solarDateTimeLatLong.latDeg)*3600 – parseFloat(solarDateTimeLatLong.latMin)*60 – parseFloat(solarDateTimeLatLong.latSec)*1;
solarDateTimeLatLong.latDeg = “-0”;
solarDateTimeLatLong.latMin = Math.floor((-latSeconds)/60);
solarDateTimeLatLong.latSec = Math.floor( (-latSeconds – (parseFloat(solarDateTimeLatLong.latMin)*60)) + 0.5);
}
else {
var latSeconds = parseFloat(solarDateTimeLatLong.latDeg)*3600 – parseFloat(solarDateTimeLatLong.latMin)*60 – parseFloat(solarDateTimeLatLong.latSec)*1;
solarDateTimeLatLong.latDeg = Math.ceil(latSeconds/3600);
solarDateTimeLatLong.latMin = Math.floor((-latSeconds + (parseFloat(solarDateTimeLatLong.latDeg)*3600))/60);
solarDateTimeLatLong.latSec = Math.floor((-latSeconds + (parseFloat(solarDateTimeLatLong.latDeg)*3600) – (parseFloat(solarDateTimeLatLong.latMin)*60)) + 0.5);
}
neg = 0;
if(solarDateTimeLatLong.lonDeg.charAt(0) == ‘-‘) {
neg = 1;
}
if(neg != 1) {
var lonSeconds = parseFloat(solarDateTimeLatLong.lonDeg)*3600 + parseFloat(solarDateTimeLatLong.lonMin)*60 + parseFloat(solarDateTimeLatLong.lonSec)*1;
solarDateTimeLatLong.lonDeg = Math.floor(lonSeconds/3600);
solarDateTimeLatLong.lonMin = Math.floor((lonSeconds – (parseFloat(solarDateTimeLatLong.lonDeg)*3600))/60);
solarDateTimeLatLong.lonSec = Math.floor((lonSeconds – (parseFloat(solarDateTimeLatLong.lonDeg)*3600) – (parseFloat(solarDateTimeLatLong.lonMin))*60) + 0.5);
}
else if(parseFloat(solarDateTimeLatLong.lonDeg) > -1) {
var lonSeconds = parseFloat(solarDateTimeLatLong.lonDeg)*3600 – parseFloat(solarDateTimeLatLong.lonMin)*60 – parseFloat(solarDateTimeLatLong.lonSec)*1;
solarDateTimeLatLong.lonDeg = “-0”;
solarDateTimeLatLong.lonMin = Math.floor((-lonSeconds)/60);
solarDateTimeLatLong.lonSec = Math.floor((-lonSeconds – (parseFloat(solarDateTimeLatLong.lonMin)*60)) + 0.5);
}
else {
var lonSeconds = parseFloat(solarDateTimeLatLong.lonDeg)*3600 – parseFloat(solarDateTimeLatLong.lonMin)*60 – parseFloat(solarDateTimeLatLong.lonSec)*1;
solarDateTimeLatLong.lonDeg = Math.ceil(lonSeconds/3600);
solarDateTimeLatLong.lonMin = Math.floor((-lonSeconds + (parseFloat(solarDateTimeLatLong.lonDeg)*3600))/60);
solarDateTimeLatLong.lonSec = Math.floor((-lonSeconds + (parseFloat(solarDateTimeLatLong.lonDeg)*3600) – (parseFloat(solarDateTimeLatLong.lonMin)*60)) + 0.5);
}
//Test for invalid lat/long input
if(latSeconds > 324000) {
alert(“You have entered an invalid latitude.\n Setting lat = 89.”);
solarDateTimeLatLong.latDeg = 89;
solarDateTimeLatLong.latMin = 0;
solarDateTimeLatLong.latSec = 0;
}
if(latSeconds < -324000) { alert(“You have entered an invalid latitude.\n Setting lat = -89.”); solarDateTimeLatLong.latDeg = -89; solarDateTimeLatLong.latMin = 0; solarDateTimeLatLong.latSec = 0; } if(lonSeconds > 648000) {
alert(“You have entered an invalid longitude.\n Setting lon = 180.”);
solarDateTimeLatLong.lonDeg = 180;
solarDateTimeLatLong.lonMin = 0;
solarDateTimeLatLong.lonSec = 0;
}
if(lonSeconds < -648000) {
alert(“You have entered an invalid longitude.\n Setting lon = -180.”);
solarDateTimeLatLong.lonDeg = -180;
solarDateTimeLatLong.lonMin = 0;
solarDateTimeLatLong.lonSec =0;
}
}

/**
* Convert radian angle to degrees
*/
function radToDeg(angleRad) {
return (180.0 * angleRad / Math.PI);
}

/**
* Convert degree angle to radians
*/
function degToRad(angleDeg) {
return (Math.PI * angleDeg / 180.0);
}

/**
* Return the numerical day-of-year from mn (January = 1), day (1-31), and lpyr (1 = TRUE) info
*/
function calcDayOfYear(mn, dy, lpyr) {
var k = (lpyr ? 1 : 2);
var doy = Math.floor((275 * mn)/9) – k * Math.floor((mn + 9)/12) + dy -30;
return doy;
}

/**
* Return string containing name of weekday from Julian Day
*/
function calcDayOfWeek(juld) {
var A = (juld + 1.5) % 7;
var DOW = (A==0)?”Sunday”:(A==1)?”Monday”:(A==2)?”Tuesday”:(A==3)?”Wednesday”:(A==4)?”Thursday”:(A==5)?”Friday”:”Saturday”;
return DOW;
}

/**
* Return Julian Day corresponding to year (4 digit year), month (January = 1), and day (1 – 31)
* Note: Number is returned for start of day. Fractional days should be added later.
*/
function calcJD(year, month, day) {
if (month <= 2) {
year -= 1;
month += 12;
}
var A = Math.floor(year/100);
var B = 2 – A + Math.floor(A/4);
var JD = Math.floor(365.25*(year + 4716)) + Math.floor(30.6001*(month+1)) + day + B – 1524.5;
return JD;
}

/**
* Return calendar date in the form DD-MONTHNAME-YYYY from Julian Day
*/
function calcDateFromJD(jd) {
var z = Math.floor(jd + 0.5);
var f = (jd + 0.5) – z;
if (z < 2299161) {
var A = z;
} else {
alpha = Math.floor((z – 1867216.25)/36524.25);
var A = z + 1 + alpha – Math.floor(alpha/4);
}
var B = A + 1524;
var C = Math.floor((B – 122.1)/365.25);
var D = Math.floor(365.25 * C);
var E = Math.floor((B – D)/30.6001);
var day = B – D – Math.floor(30.6001 * E) + f;
var month = (E < 14) ? E – 1 : E – 13; var year = (month > 2) ? C – 4716 : C – 4715;
// alert (“date: ” + day + “-” + monthList[month-1].name + “-” + year);
return (day + “-” + monthList[month-1].name + “-” + year);
}

/**
* Return calendar day in the form DD-MONTH (minus year) from Julian Day
*/
function calcDayFromJD(jd) {
var z = Math.floor(jd + 0.5);
var f = (jd + 0.5) – z;
if (z < 2299161) {
var A = z;
} else {
alpha = Math.floor((z – 1867216.25)/36524.25);
var A = z + 1 + alpha – Math.floor(alpha/4);
}
var B = A + 1524;
var C = Math.floor((B – 122.1)/365.25);
var D = Math.floor(365.25 * C);
var E = Math.floor((B – D)/30.6001);
var day = B – D – Math.floor(30.6001 * E) + f;
var month = (E < 14) ? E – 1 : E – 13; var year = (month > 2) ? C – 4716 : C – 4715;
return ((day<10 ? “0” : “”) + day + monthList[month-1].abbr); } /** * Return the T value corresponding to the Julian Day converted to centuries since J2000.0 */ function calcTimeJulianCent(jd) { var T = (jd – 2451545.0)/36525.0; return T; } /** * Return the number of Julian centuries since J2000.0 corresponding to the t value */ function calcJDFromJulianCent(t) { var JD = t * 36525.0 + 2451545.0; return JD; } /** * Return the Geometric Mean Longitude of the Sun in degrees for t */ 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 } /** * Return the Geometric Mean Anomaly of the Sun in degrees for t */ function calcGeomMeanAnomalySun(t) { var M = 357.52911 + t * (35999.05029 – 0.0001537 * t); return M; // in degrees } /** * Return the unitless eccentricity of earth’s orbit for t */ function calcEccentricityEarthOrbit(t) { var e = 0.016708634 – t * (0.000042037 + 0.0000001267 * t); return e; // unitless } /** * Calculate the equation of center for the sun for t */ 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 } /** * Return sun’s true longitude in degrees for t */ function calcSunTrueLong(t) { var l0 = calcGeomMeanLongSun(t); var c = calcSunEqOfCenter(t); var O = l0 + c; return O; // in degrees } /** * Return sun’s true anamoly in degrees for t */ function calcSunTrueAnomaly(t) { var m = calcGeomMeanAnomalySun(t); var c = calcSunEqOfCenter(t); var v = m + c; return v; // in degrees } /** * Return the distance to the sun (sun radius vector) in AUs for t */ 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 } /** * Return sun’s apparent longitude in degrees for t */ 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 } /** * Return mean obliquity of the ecliptic in degrees for t */ 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 } /** * Return corrected obliquity of the ecliptic in degrees for t */ 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 } /** * Return sun’s right ascension in degrees for t */ 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 } /** * Return sun’s declination in degrees for t */ 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 } /** * Calculate the difference between true solar time and mean solar time for t * Return 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 } /** * Return hour angle of the sun at sunrise in radians for latitude of observer in degrees and declination angle of sun in degrees */ 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 } /** * Return hour angle of of the sun at sunset in radians for latitude of observer in degrees and declination angle of sun in degrees */ 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 } /** * Return the Universal Coordinated Time (UTC) of sunrise for the given Julian Day at the given location on earth in degrees 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); // Second pass includes fractional jday in gamma calc var newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC/1440.0); eqTime = calcEquationOfTime(newt); solarDec = calcSunDeclination(newt); hourAngle = calcHourAngleSunrise(latitude, solarDec); delta = longitude – radToDeg(hourAngle); timeDiff = 4 * delta; timeUTC = 720 + timeDiff – eqTime; // in minutes // alert(“eqTime = ” + eqTime + “\nsolarDec = ” + solarDec + “\ntimeUTC = ” + timeUTC); return timeUTC; } /** * Return the Universal Coordinated Time (UTC) of solar noon for the given day at the given location on earth in degrees in minutes from zero Z */ function calcSolNoonUTC(t, longitude) { // First pass uses approximate solar noon to calculate eqtime var tnoon = calcTimeJulianCent(calcJDFromJulianCent(t) + longitude/360.0); var eqTime = calcEquationOfTime(tnoon); var solNoonUTC = 720 + (longitude * 4) – eqTime; // min var newt = calcTimeJulianCent(calcJDFromJulianCent(t) -0.5 + solNoonUTC/1440.0); eqTime = calcEquationOfTime(newt); // var solarNoonDec = calcSunDeclination(newt); solNoonUTC = 720 + (longitude * 4) – eqTime; // min return solNoonUTC; } /** * Return the Universal Coordinated Time (UTC) of sunset for the given day at the given location on earth in degrees in minutes from zero Z */ function calcSunsetUTC(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 calculates sunrise and approx length of day var eqTime = calcEquationOfTime(tnoon); var solarDec = calcSunDeclination(tnoon); var hourAngle = calcHourAngleSunset(latitude, solarDec); var delta = longitude – radToDeg(hourAngle); var timeDiff = 4 * delta; var timeUTC = 720 + timeDiff – eqTime; // first pass used to include fractional day in gamma calc var newt = calcTimeJulianCent(calcJDFromJulianCent(t) + timeUTC/1440.0); eqTime = calcEquationOfTime(newt); solarDec = calcSunDeclination(newt); hourAngle = calcHourAngleSunset(latitude, solarDec); delta = longitude – radToDeg(hourAngle); timeDiff = 4 * delta; timeUTC = 720 + timeDiff – eqTime; // in minutes return timeUTC; } /** * Return the decimal latitude from the degrees, minutes and seconds entered into a form */ function getLatitude() { var neg = 0; var strLatDeg = solarDateTimeLatLong.latDeg; var degs = parseFloat(solarDateTimeLatLong.latDeg); if (solarDateTimeLatLong.latDeg.charAt(0) == ‘-‘) { neg = 1; } if (strLatDeg.indexOf(“.”) != -1) { solarDateTimeLatLong.latMin = 0; solarDateTimeLatLong.latSec = 0; } if(solarDateTimeLatLong.latMin == “”) { solarDateTimeLatLong.latMin = 0; } if(solarDateTimeLatLong.latSec == “”) { solarDateTimeLatLong.latSec = 0; } var mins = parseFloat(solarDateTimeLatLong.latMin); var secs = parseFloat(solarDateTimeLatLong.latSec); if(neg != 1) { var decLat = degs + (mins / 60) + (secs / 3600); } else if(neg == 1) { var decLat = degs – (mins / 60) – (secs / 3600); } else { return -9999; } return decLat; } /** * Return the decimal longitude from the degrees, minutes and seconds entered into a form */ function getLongitude() { var neg = 0; var strLonDeg = solarDateTimeLatLong.lonDeg; var degs = parseFloat(solarDateTimeLatLong.lonDeg); if (solarDateTimeLatLong.lonDeg.charAt(0) == ‘-‘) { neg = 1; } if (strLonDeg.indexOf(“.”) != -1) { solarDateTimeLatLong.lonMin = 0; solarDateTimeLatLong.lonSec = 0; } if(solarDateTimeLatLong.lonMin == “”) { solarDateTimeLatLong.lonMin = 0; } if(solarDateTimeLatLong.lonSec == “”) { solarDateTimeLatLong.lonSec = 0; } var mins = parseFloat(solarDateTimeLatLong.lonMin); var secs = parseFloat(solarDateTimeLatLong.lonSec); var decLon = degs + (mins / 60) + (secs / 3600); if(neg != 1) { var decLon = degs + (mins / 60) + (secs / 3600); } else if(neg == 1) { var decLon = degs – (mins / 60) – (secs / 3600); } else { return -9999; } return decLon; } /** * Return the Julian Day of the most recent sunrise starting from the given day at the given location on earth in degrees */ function findRecentSunrise(jd, latitude, longitude) { var julianday = jd; var time = calcSunriseUTC(julianday, latitude, longitude); while(!isNumber(time)) { julianday -= 1.0; time = calcSunriseUTC(julianday, latitude, longitude); } return julianday; } /** * Return the Julian Day of the most recent sunset starting from the given day at the given location on earth in degrees */ function findRecentSunset(jd, latitude, longitude) { var julianday = jd; var time = calcSunsetUTC(julianday, latitude, longitude); while(!isNumber(time)) { julianday -= 1.0; time = calcSunsetUTC(julianday, latitude, longitude); } return julianday; } /** * Return the Julian Day of the next sunrise starting from the given day at the given location on earth in degrees */ function findNextSunrise(jd, latitude, longitude) { var julianday = jd; var time = calcSunriseUTC(julianday, latitude, longitude); while(!isNumber(time)) { julianday += 1.0; time = calcSunriseUTC(julianday, latitude, longitude); } return julianday; } /** * Return calculate the Julian Day of the next sunset starting from the given day at the given location on earth in degrees */ function findNextSunset(jd, latitude, longitude) { var julianday = jd; var time = calcSunsetUTC(julianday, latitude, longitude); while(!isNumber(time)) { julianday += 1.0; time = calcSunsetUTC(julianday, latitude, longitude); } return julianday; } /** * Return time of day in minutes to a zero-padded string suitable for printing to the form text fields in the format HH:MM:SS for a time of day in minutes */ function timeString(minutes) { // timeString returns a zero-padded string (HH:MM:SS) given time in minutes var floatHour = minutes / 60.0; var hour = Math.floor(floatHour); var floatMinute = 60.0 * (floatHour – Math.floor(floatHour)); var minute = Math.floor(floatMinute); var floatSec = 60.0 * (floatMinute – Math.floor(floatMinute)); var second = Math.floor(floatSec + 0.5); if (second > 59) {
second = 0;
minute += 1;
}
var timeStr = hour + “:”;
if (minute < 10) // i.e. only one digit
timeStr += “0” + minute + “:”;
else
timeStr += minute + “:”;
if (second < 10) // i.e. only one digit timeStr += “0” + second; else timeStr += second; return timeStr; } /** * Return time of day in minutes to a zero-padded string suitable for printing to the form text fields in the format HH:MM[AM/PM] (DDMon) for time of Julian Day in minutes * If time crosses a day boundary, date is appended. * Return a zero-padded string (HH:MM *M) given time in minutes and appends short date if time is > 24 or < 0, resp. */ function timeStringShortAMPM(minutes, JD) { var julianday = JD; var floatHour = minutes / 60.0; var hour = Math.floor(floatHour); var floatMinute = 60.0 * (floatHour – Math.floor(floatHour)); var minute = Math.floor(floatMinute); var floatSec = 60.0 * (floatMinute – Math.floor(floatMinute)); var second = Math.floor(floatSec + 0.5); var PM = false; minute += (second >= 30)? 1 : 0;
if (minute >= 60) {
minute -= 60;
hour ++;
}
var daychange = false;
if (hour > 23) {
hour -= 24;
daychange = true;
julianday += 1.0;
}
if (hour < 0) { hour += 24; daychange = true; julianday -= 1.0; } if (hour > 12) {
hour -= 12;
PM = true;
}
if (hour == 12) {
PM = true;
}
if (hour == 0) {
PM = false;
hour = 12;
}
var timeStr = hour + “:”;
if (minute < 10) // i.e. only one digit timeStr += “0” + minute + ((PM)?”PM”:”AM”); else timeStr += “” + minute + ((PM)?”PM”:”AM”); if (daychange) return timeStr + ” ” + calcDayFromJD(julianday); return timeStr; } /** * Return time of day in minutes to a zero-padded string suitable for printing to the form text fields, and appends the date in the format HH:MM[AM/PM] DDMon for time of Julian Day in minutes * Return a zero-padded string (HH:MM[AM/PM]) given time in minutes and Julian Day, and appends the short date */ function timeStringAMPMDate(minutes, JD) { var julianday = JD; var floatHour = minutes / 60.0; var hour = Math.floor(floatHour); var floatMinute = 60.0 * (floatHour – Math.floor(floatHour)); var minute = Math.floor(floatMinute); var floatSec = 60.0 * (floatMinute – Math.floor(floatMinute)); var second = Math.floor(floatSec + 0.5); minute += (second >= 30)? 1 : 0;
if (minute >= 60) {
minute -= 60;
hour ++;
}
if (hour > 23) {
hour -= 24;
julianday += 1.0;
}
if (hour < 0) { hour += 24; julianday -= 1.0; } var PM = false; if (hour > 12) {
hour -= 12;
PM = true;
}
if (hour == 12) {
PM = true;
}
if (hour == 0) {
PM = false;
hour = 12;
}
var timeStr = hour + “:”;
if (minute < 10) // i.e. only one digit timeStr += “0” + minute + ((PM)?”PM”:”AM”); else timeStr += minute + ((PM)?”PM”:”AM”); return timeStr + ” ” + calcDayFromJD(julianday); } /** * Return time of day in minutes to a zero-padded 24hr time suitable for printing to the form text fields in the format HH:MM (DDMon for time of Julian Day in minutes * If time crosses a day boundary, date is appended. * Return a zero-padded string (HH:MM) given time in minutes and Julian Day, and appends the short date if time crosses a day boundary */ function timeStringDate(minutes, JD) { var julianday = JD; var floatHour = minutes / 60.0; var hour = Math.floor(floatHour); var floatMinute = 60.0 * (floatHour – Math.floor(floatHour)); var minute = Math.floor(floatMinute); var floatSec = 60.0 * (floatMinute – Math.floor(floatMinute)); var second = Math.floor(floatSec + 0.5); minute += (second >= 30)? 1 : 0;
if (minute >= 60) {
minute -= 60;
hour ++;
}
var daychange = false;
if (hour > 23) {
hour -= 24;
julianday += 1.0;
daychange = true;
}
if (hour < 0) {
hour += 24;
julianday -= 1.0;
daychange = true;
}
var timeStr = hour + “:”;
if (minute < 10) // i.e. only one digit timeStr += “0” + minute; else timeStr += minute; if (daychange) return timeStr + ” ” + calcDayFromJD(julianday); return timeStr; } /** * Calculate time of sunrise and sunset for the entered date and location and defines global solarRiseSet values. * In the special cases near earth’s poles, the date of nearest sunrise and set are reported. */ function calcSun() { var latitude = getLatitude(); var longitude = getLongitude(); var indexRS = solarDateTimeLatLong.mos; if (isValidInput(indexRS)) { if((latitude >= -90) && (latitude < -89)) {
alert(“All latitudes between 89 and 90 S\n will be set to -89”);
solarDateTimeLatLong.latDeg = -89;
latitude = -89;
}
if ((latitude <= 90) && (latitude > 89)) {
alert(“All latitudes between 89 and 90 N\n will be set to 89”);
solarDateTimeLatLong.latDeg = 89;
latitude = 89;
}
// Calculate the time of sunrise
var JD = calcJD(parseFloat(solarDateTimeLatLong.year), indexRS + 1, parseFloat(solarDateTimeLatLong.day));
var dow = calcDayOfWeek(JD);
var doy = calcDayOfYear(indexRS + 1, parseFloat(solarDateTimeLatLong.day), isLeapYear(solarDateTimeLatLong.year));
var T = calcTimeJulianCent(JD);
var alpha = calcSunRtAscension(T);
var theta = calcSunDeclination(T);
var Etime = calcEquationOfTime(T);
// solarRiseSet.dbug = doy;
var eqTime = Etime;
var solarDec = theta;
// Calculate sunrise for this date if no sunrise is found, set flag nosunrise
var nosunrise = false;
var riseTimeGMT = calcSunriseUTC(JD, latitude, longitude);
if (!isNumber(riseTimeGMT)) {
nosunrise = true;
}
// Calculate sunset for this date if no sunset is found, set flag nosunset
var nosunset = false;
var setTimeGMT = calcSunsetUTC(JD, latitude, longitude);
if (!isNumber(setTimeGMT)) {
nosunset = true;
}
var daySavings = solarDateTimeLatLong.daySavings; // = 0 (no) or 60 (yes)
var zone = solarDateTimeLatLong.hrsToGMT;
if(zone > 12 || zone < -12.5) { alert(“The offset must be between -12.5 and 12. \n Setting \”Off-Set\”=0”); zone = “0”; solarDateTimeLatLong.hrsToGMT = zone; } if (!nosunrise) { // Sunrise was found var riseTimeLST = riseTimeGMT – (60 * zone) + daySavings; // in minutes var riseStr = timeStringShortAMPM(riseTimeLST, JD); var utcRiseStr = timeStringDate(riseTimeGMT, JD); solarRiseSet.sunrise = riseStr; solarRiseSet.utcSunrise = utcRiseStr; } if (!nosunset) { // Sunset was found var setTimeLST = setTimeGMT – (60 * zone) + daySavings; var setStr = timeStringShortAMPM(setTimeLST, JD); var utcSetStr = timeStringDate(setTimeGMT, JD); solarRiseSet.sunset = setStr; solarRiseSet.utcSunset = utcSetStr; } // Calculate solar noon for this date var solNoonGMT = calcSolNoonUTC(T, longitude); var solNoonLST = solNoonGMT – (60 * zone) + daySavings; var solnStr = timeString(solNoonLST); var utcSolnStr = timeString(solNoonGMT); solarRiseSet.solnoon = solnStr; solarRiseSet.utcSolnoon = utcSolnStr; var tsnoon = calcTimeJulianCent(calcJDFromJulianCent(T) -0.5 + solNoonGMT/1440.0); eqTime = calcEquationOfTime(tsnoon); solarDec = calcSunDeclination(tsnoon); solarRiseSet.eqTime = (Math.floor(100*eqTime))/100; solarRiseSet.solarDec = (Math.floor(100*(solarDec)))/100; // Convert lat and long to standard format convLatLong(); // report special cases of no sunrise if(nosunrise) { solarRiseSet.utcSunrise = “”; // if Northern hemisphere and spring or summer, OR // if Southern hemisphere and fall or winter, use // previous sunrise and next sunset if (((latitude > 66.4) && (doy > 79) && (doy < 267)) || ((latitude < -66.4) && ((doy < 83) || (doy > 263)))) {
newjd = findRecentSunrise(JD, latitude, longitude);
newtime = calcSunriseUTC(newjd, latitude, longitude) – (60 * zone) + daySavings;
if (newtime > 1440) {
newtime -= 1440;
newjd += 1.0;
}
if (newtime < 0) { newtime += 1440; newjd -= 1.0; } solarRiseSet.sunrise = timeStringAMPMDate(newtime, newjd); solarRiseSet.utcSunrise = “prior sunrise”; } // if Northern hemisphere and fall or winter, OR // if Southern hemisphere and spring or summer, use // next sunrise and previous sunset else if (((latitude > 66.4) && ((doy < 83) || (doy > 263))) || ((latitude < -66.4) && (doy > 79) && (doy < 267))) { newjd = findNextSunrise(JD, latitude, longitude); newtime = calcSunriseUTC(newjd, latitude, longitude) – (60 * zone) + daySavings; if (newtime > 1440) {
newtime -= 1440;
newjd += 1.0;
}
if (newtime < 0) { newtime += 1440; newjd -= 1.0; } solarRiseSet.sunrise = timeStringAMPMDate(newtime, newjd); // solarRiseSet.sunrise = calcDayFromJD(newjd) + ” ” + timeStringDate(newtime, newjd); solarRiseSet.utcSunrise = “next sunrise”; } else { alert(“Cannot Find Sunrise!”); } // alert(“Last Sunrise was on day ” + findRecentSunrise(JD, latitude, longitude)); // alert(“Next Sunrise will be on day ” + findNextSunrise(JD, latitude, longitude)); } if(nosunset) { solarRiseSet.utcSunset = “”; // if Northern hemisphere and spring or summer, OR // if Southern hemisphere and fall or winter, use // previous sunrise and next sunset if (((latitude > 66.4) && (doy > 79) && (doy < 267)) || ((latitude < -66.4) && ((doy < 83) || (doy > 263)))) {
newjd = findNextSunset(JD, latitude, longitude);
newtime = calcSunsetUTC(newjd, latitude, longitude) – (60 * zone) + daySavings;
if (newtime > 1440) {
newtime -= 1440;
newjd += 1.0;
}
if (newtime < 0) { newtime += 1440; newjd -= 1.0; } solarRiseSet.sunset = timeStringAMPMDate(newtime, newjd); solarRiseSet.utcSunset = “next sunset”; solarRiseSet.utcSolnoon = “”; } // if Northern hemisphere and fall or winter, OR // if Southern hemisphere and spring or summer, use // next sunrise and last sunset else if (((latitude > 66.4) && ((doy < 83) || (doy > 263))) || ((latitude < -66.4) && (doy > 79) && (doy < 267))) { newjd = findRecentSunset(JD, latitude, longitude); newtime = calcSunsetUTC(newjd, latitude, longitude) – (60 * zone) + daySavings; if (newtime > 1440) {
newtime -= 1440;
newjd += 1.0;
}
if (newtime < 0) {
newtime += 1440;
newjd -= 1.0;
}
solarRiseSet.sunset = timeStringAMPMDate(newtime, newjd);
solarRiseSet.utcSunset = “prior sunset”;
solarRiseSet.solnoon = “N/A”;
solarRiseSet.utcSolnoon = “”;
}
else {
alert (“Cannot Find Sunset!”);
}
}
}
}