关于某地某天昼夜长短的具体算法,在《地球概论》、《普通天文学》、《球面天文学》等书籍中,都详细载明计算昼夜长度的公式,可以查阅。现将公式写在下面并进行讨论: (1) Cost=-tgδtgφ公式中的φ是地理纬度,北半球取正值,如北回归线的纬度是北纬23°26′,则φ=+23°26′;南半球取负值,如南极圈的纬度是南纬66°34′,则φ=-66°34′。δ是太阳赤纬,就是太阳在地球上垂直照射的纬度数值。太阳在一年中往返垂直照射南北回归线之间,所以,在一 Regarding the specific algorithm for the length of day and night in a place, the formulas for calculating the length of day and night can be found in books such as “Earth Introduction,” “Ordinary Astronomy,” and “Spherical Astronomy.” The formula is written below and discussed: (1) In the formula of Cost=-tgδtgφ, φ is the geographical latitude and the northern hemisphere is a positive value. For example, the latitude of the Tropic of Cancer is 23°26′N, then φ=+23°26′. The southern hemisphere takes negative values. For example, the latitude of the Antarctic circle is 66°34’S, and φ=-66°34’. δ is the declination of the sun, which is the latitude of the sun on the earth. The sun travels back and forth between the vertical lines of the Tropic of the South and the Tropics of the year, so in one