What is the geographical relationship between the weather getting dark in the morning and evening?

It has something to do with latitude. The higher the latitude, the longer the days in summer and the longer the nights in winter.

It gets dark in the morning and evening, which is related to the height angle of the sun.

For example, on the day of summer solstice, the sun shines directly on the Tropic of Cancer, and the solar altitude angle in the northern region is the largest, so the sunshine time (daytime time) on this day is the longest.

On the solstice of winter, the sunshine time is the shortest.