根据日出/日落计算是否接近黎明/黄昏?

问题描述

如果我有时间看日出、日落以及特定位置的经度和纬度，是否可以计算出黎明/黄昏的时间?

解决方案

有一些 simplified 等式，但真正的事情是这样的:

• 拍的，所以应该也有生成小程序的地方.在 WEB 上找不到任何天文太阳历的图像，所以这里是从我的一本非常旧的书中扫描出来的:

  展位是一样的，但扫描仅针对单个长/纬度地理位置.

  • x 轴是日期

  • y 轴是太阳到达的时间(日出/日落或黄昏/黎明，...)

  • Noc 表示夜晚，Den 表示白天

  • 所有的分数对你来说都不重要

  • 破折号线是日出/日落(在数学水平的领先视觉边缘)

  • 虚线线是民用暮光(视觉太阳中心在水平线以下6度)

  • 实心线是天文暮光(视觉太阳中心在水平线以下18度)

    图表适用于纬度 48,49,50 度，航海黄昏(视觉太阳中心在地平线以下 12 度)不是在图像上.当您通过多项式或分段折线近似此曲线时，您可以轻松计算每个日期所需的内容，除非您想使用它数千年，然后您可以将其作为周期函数，因此您只需要一个年份表和所有其他年份是一样的.

  [备注]

  视觉效果

  • 表示几何位置+大气折射+像差+进动/章动+光速
  • near Horizo​​n 的差异比 0.5 度数多一点！！！(一张太阳盘)
  • 时差在8分钟左右

  Is it possible to calculate when dawn/dusk will be if I have the time for sunrise, sunset and the longitude and latitude of a particular location?

  解决方案

  there are some simplified equations for that but the real thing is this:

  • solving Kepler's equation
  • btw your question is very similar to this: time when the sun is X degrees below/above Horizon

  if you want easy solution then obtain sunrise calendar for your location

  it should look something like this:

  Just pick the closest latitude or generate the right diagram for your location. The picture was taken from here so there should be also the generation applet somewhere. Can't find any image of the astronomy sun calendar on the WEB so here is scan from really old book of mine:

  Booth are the same thing but the scan is just for single long/lat geo-location.

  • x axis is the date

  • y axis is the time sun reach (sun rise/set or dusk/dawn,...)

  • Noc means night and Den means day

  • all the marks are unimportant for you

  • dash dash line is sun rise/set (leading visual edge at mathematical horizont)

  • dash dot line is the civil twilight (visual center of sun is 6 deg below horizont)

  • filled line is astronomical twilight (visual center of sun is 18 deg below horizont)

    Diagram is for latitudes 48,49,50 deg, nautical twilight (visual center of sun is 12 deg below horizon) is not on the image. When you approximate this curve by polynomial or piecewise polyline then you can easily compute what you need per any date unless you want to use this for thousands of years then you can take this as periodic function so you need just one year table and all the other years are the same.

  [Notes]

  visual

  • means geometric position + atmospheric refraction + aberation + precession/nutation + speed of light
  • near horizon is the difference little more then 0.5 degree !!! (one Sun disc)
  • and the time difference is around 8 minutes

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