根据日出/日落计算它是否接近黎明/黄昏？ [英] Calculate whether it is close to dawn/dusk based on sunrise/sunset?

问题描述

如果我有时间拍摄日出，日落以及特定地点的经度和纬度，是否可以计算黎明/黄昏的时间？

解决方案

有一些简化的方程，但真实的是这样的：

• 获取的，所以应该还有一代applet。在WEB上找不到天文学日历的任何图像，所以这里是从我的真正旧书中扫描出来的： $ b
  
  
  

  展位是一样的，但扫描仅适用于单个长/纬度地理位置
  
  $ ul
  $ b

• y 轴是太阳到达的时间（太阳升起/集合或黄昏/黎明，...）

• Noc 表示晚上，表示表示
所有分数对您而言都不重要强行>短划线线是太阳升起/设置（在数学水平线上领先视觉边缘） 是暮光之城（视觉太阳中心位于水平线以下6度） visual 太阳的中心位于水平面以下18度）




图纬度 48,49,50 deg ，航海曙光（视觉太阳中心< 12 deg 低于地平线）不在图像上。当你用多项式或分段多段线近似这条曲线时，你可以很容易地计算出你需要的每一个日期，除非你想用这个数千年，那么你可以把它作为周期函数，所以你只需要一年的表和所有其他的年份是相同的。

视觉

• 表示几何位置+大气折射+ aberation +岁差/章动+光速


• 接近地平线的差异小于 0.5 度!!! （一张Sun光盘）


• ，时间差约为 8 分钟
  

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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