Look at the picture (sunshine map of the sun)

The longitude of this picture is a bit blurred. I regard it as dividing the earth into 12 parts. If the interval between every two adjacent meridians is 30, please correct it again. There are plenty of days in and around the Arctic Circle, so this is the summer solstice. The latitude of the direct point of the sun is 23 26 ′ n, and the longitude depends on which meridian is 12 hour. It should be 0 meridian from the picture. 1 and 2 are both on the morning line, because it will enter the day along the direction of the earth's rotation. The sunrise time of 1 is 4 o'clock. Because there are sunrises in two places at this time, and two places are two hours earlier than 1 place. 1 day length =( 12-4)×2= 16 hours. At this time, Beijing time is 20 o'clock. Because the longitude of 0 is 12 at this time, Beijing is east of 0 120, 8 hours earlier than 0. It's 2: 06. Because 2 is on the morning line, on the equator. The intersection of the equator and the morning line is 6 o'clock local time. The sun rises in the east and sets in the west. At this time, it is the summer solstice. The sun rises in the east and then moves to the northern sky. At noon, it is the northernmost and highest, and then falls to the west. So the shadow change of the second flagpole is first west, then south and then east. (West-Southeast) At noon that day, the height of the sun was the highest in Guangzhou. Because noon in Guangzhou is closest to the Tropic of Cancer at this time. A little messy, hehe. You can ask questions if you don't understand.