What is the length of sunshine related to?

And the length of sunshine. First, sunlight is produced by the rotation of the earth and the revolution of the earth around the sun. It is precisely because of the earth's rotation and revolution that China has 24 solar terms. Moreover, on the "summer solstice", the average sunshine in China is the longest in the whole year; On the day of "Winter Solstice", the average sunshine time in China is the shortest. Second, it is the location of the earth where we are, for example, at the poles of the earth, such a situation will happen: a certain time is night; It will also happen at some time, all during the day. We alternate day and night.