The length of day in the Antarctic Circle, Tropic of cancer, equator, Tropic of cancer, Arctic circle

The length of day in the Antarctic Circle, Tropic of cancer, equator, Tropic of cancer, Arctic circle

The specific calculation process involves a lot of solid geometry, which is inconvenient for me to write in. The general idea is to use the date to calculate the latitude of the direct solar point or the angle formed by the direct solar direction and the equatorial plane, use this angle to calculate the intersection of the day and night boundary and the latitude circle where the observation point is located, and use the intersection to calculate the night arc (or day arc) on the circle