计算太阳位置的方程:solar-calculator

jopen 9年前

计算太阳位置的方程:solar-calculator。计算太阳位置的方程:solar-calculator

#    <!DOCTYPE html>  <meta charset="utf-8">  <style>    path {    fill: none;    stroke-linecap: round;    stroke-linejoin: round;  }    text {    font: 10px sans-serif;  }    .horizon {    stroke: #000;    stroke-width: 1.5px;  }    .graticule {    stroke: #000;    stroke-opacity: .15;  }    .analemmas path {    stroke: #f00;    stroke-width: 2px;  }    .ticks line {    stroke: #000;  }    .ticks text {    text-anchor: middle;  }    .ticks--azimuth text:nth-of-type(9n + 1) {    font-weight: bold;    font-size: 14px;  }    </style>  <body>  <script src="http://d3js.org/d3.v3.min.js"></script>  <script src="solar-calculator.js"></script>  <script>    var π = Math.PI,      τ = 2 * π,      radians = π / 180,      degrees = 180 / π;    var width = 960,      height = 960,      scale = width * .45;    var solar = solarCalculator([-122, 37]),      start = d3.time.year.utc.floor(new Date),      end = d3.time.year.utc.offset(start, 1);    var projection = d3.geo.projection(flippedStereographic)      .scale(scale)      .clipAngle(130)      .rotate([0, -90])      .translate([width / 2 + .5, height / 2 + .5])      .precision(.1);    var path = d3.geo.path()      .projection(projection);    var svg = d3.select("body").append("svg")      .attr("width", width)      .attr("height", height);    svg.append("path")      .datum(d3.geo.circle().origin([0, 90]).angle(90))      .attr("class", "horizon")      .attr("d", path);    svg.append("path")      .datum(d3.geo.graticule())      .attr("class", "graticule")      .attr("d", path);    var ticksAzimuth = svg.append("g")      .attr("class", "ticks ticks--azimuth");    ticksAzimuth.selectAll("line")      .data(d3.range(360))    .enter().append("line")      .each(function(d) {        var p0 = projection([d, 0]),            p1 = projection([d, d % 10 ? -1 : -2]);          d3.select(this)            .attr("x1", p0[0])            .attr("y1", p0[1])            .attr("x2", p1[0])            .attr("y2", p1[1]);      });    ticksAzimuth.selectAll("text")      .data(d3.range(0, 360, 10))    .enter().append("text")      .each(function(d) {        var p = projection([d, -4]);          d3.select(this)            .attr("x", p[0])            .attr("y", p[1]);      })      .attr("dy", ".35em")      .text(function(d) { return d === 0 ? "N" : d === 90 ? "E" : d === 180 ? "S" : d === 270 ? "W" : d + "°"; });    svg.append("g")      .attr("class", "ticks ticks--elevation")    .selectAll("text")      .data(d3.range(10, 91, 10))    .enter().append("text")      .each(function(d) {        var p = projection([0, d]);          d3.select(this)            .attr("x", p[0])            .attr("y", p[1]);      })      .attr("dy", ".35em")      .text(function(d) { return d + "°"; });    svg.insert("g", ".sphere")      .attr("class", "analemmas")    .selectAll("path")      .data(d3.range(24))    .enter().append("path")      .datum(function(h) { return {type: "LineString", coordinates: d3.time.days.utc(start, end).map(function(d) { return solar.position(d3.time.hour.utc.offset(d, h)); })}; })      .attr("d", path);    d3.select(self.frameElement).style("height", height + "px");    function flippedStereographic(λ, φ)  {    var cosλ = Math.cos(λ),        cosφ = Math.cos(φ),        k = 1 / (1 + cosλ * cosφ);    return [      k * cosφ * Math.sin(λ),      -k * Math.sin(φ)    ];  }    </script>
solar-calculator.js#    // Equations based on NOAA’s Solar Calculator; all angles in radians.  // http://www.esrl.noaa.gov/gmd/grad/solcalc/    (function() {    var J2000 = Date.UTC(2000, 0, 1, 12),        π = Math.PI,        τ = 2 * π,        radians = π / 180,        degrees = 180 / π;      solarCalculator = function(location) {      var longitude = location[0],          minutesOffset = 720 - longitude * 4,          λ = location[0] * radians,          φ = location[1] * radians,          cosφ = Math.cos(φ),          sinφ = Math.sin(φ);        function position(date) {        var centuries = (date - J2000) / (864e5 * 36525),            θ = solarDeclination(centuries),            cosθ = Math.cos(θ),            sinθ = Math.sin(θ),            azimuth = ((date - d3.time.day.utc.floor(date)) / 864e5 * τ + equationOfTime(centuries) + λ) % τ - π,            zenith = Math.acos(Math.max(-1, Math.min(1, sinφ * sinθ + cosφ * cosθ * Math.cos(azimuth)))),            azimuthDenominator = cosφ * Math.sin(zenith);          if (azimuth < -π) azimuth += τ;        if (Math.abs(azimuthDenominator) > 1e-6) azimuth = (azimuth > 0 ? -1 : 1) * (π - Math.acos(Math.max(-1, Math.min(1, (sinφ * Math.cos(zenith) - sinθ) / azimuthDenominator))));        if (azimuth < 0) azimuth += τ;          // Correct for atmospheric refraction.        var atmosphere = 90 - zenith * degrees;        if (atmosphere <= 85) {          var te = Math.tan(atmosphere * radians);          zenith -= (atmosphere > 5 ? 58.1 / te - .07 / (te * te * te) + .000086 / (te * te * te * te * te)              : atmosphere > -.575 ? 1735 + atmosphere * (-518.2 + atmosphere * (103.4 + atmosphere * (-12.79 + atmosphere * .711)))              : -20.774 / te) / 3600 * radians;        }          // Note: if zenith > 108°, it’s dark.        return [azimuth * degrees, 90 - zenith * degrees];      }        function noon(date) {        var centuries = (d3.time.day.utc.floor(date) - J2000) / (864e5 * 36525),            minutes = (minutesOffset - (equationOfTime(centuries + (minutesOffset - (equationOfTime(centuries - longitude / (360 * 365.25 * 100)) * degrees * 4)) / (1440 * 365.25 * 100)) * degrees * 4) - date.getTimezoneOffset()) % 1440;        if (minutes < 0) minutes += 1440;        return new Date(+d3.time.day.floor(date) + minutes * 60 * 1000);      }        return {        position: position,        noon: noon      };    };      function equationOfTime(centuries) {      var e = eccentricityEarthOrbit(centuries),          m = solarGeometricMeanAnomaly(centuries),          l = solarGeometricMeanLongitude(centuries),          y = Math.tan(obliquityCorrection(centuries) / 2);      y *= y;      return y * Math.sin(2 * l)          - 2 * e * Math.sin(m)          + 4 * e * y * Math.sin(m) * Math.cos(2 * l)          - 0.5 * y * y * Math.sin(4 * l)          - 1.25 * e * e * Math.sin(2 * m);    }      function solarDeclination(centuries) {      return Math.asin(Math.sin(obliquityCorrection(centuries)) * Math.sin(solarApparentLongitude(centuries)));    }      function solarApparentLongitude(centuries) {      return solarTrueLongitude(centuries) - (0.00569 + 0.00478 * Math.sin((125.04 - 1934.136 * centuries) * radians)) * radians;    }      function solarTrueLongitude(centuries) {      return solarGeometricMeanLongitude(centuries) + solarEquationOfCenter(centuries);    }      function solarGeometricMeanAnomaly(centuries) {      return (357.52911 + centuries * (35999.05029 - 0.0001537 * centuries)) * radians;    }      function solarGeometricMeanLongitude(centuries) {      var l = (280.46646 + centuries * (36000.76983 + centuries * 0.0003032)) % 360;      return (l < 0 ? l + 360 : l) / 180 * π;    }      function solarEquationOfCenter(centuries) {      var m = solarGeometricMeanAnomaly(centuries);      return (Math.sin(m) * (1.914602 - centuries * (0.004817 + 0.000014 * centuries))          + Math.sin(m + m) * (0.019993 - 0.000101 * centuries)          + Math.sin(m + m + m) * 0.000289) * radians;    }      function obliquityCorrection(centuries) {      return meanObliquityOfEcliptic(centuries) + 0.00256 * Math.cos((125.04 - 1934.136 * centuries) * radians) * radians;    }      function meanObliquityOfEcliptic(centuries) {      return (23 + (26 + (21.448 - centuries * (46.8150 + centuries * (0.00059 - centuries * 0.001813))) / 60) / 60) * radians;    }      function eccentricityEarthOrbit(centuries) {      return 0.016708634 - centuries * (0.000042037 + 0.0000001267 * centuries);    }  })();

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