Sunlight signal for judging solar terms

(1) Look at the map, the Arctic Circle and its northern region are extremely daytime, which is the summer solstice in the northern hemisphere.

(2) During the summer solstice, the noon sun height decreases from the Tropic of Cancer to the north and south sides, and the minimum noon sun height is a; The days are long and the nights are short in the northern hemisphere. The higher the latitude, the longer the day, the shorter the night, and the longest day at point A; The solar arc at the latitude of point A determines that the day length of point A is 20 hours.

(3) Point B is located at the intersection of the morning line and the equator at 6: 00 local time; Point C is at noon, and the local time is12: 00; According to the local time of the 0 meridian in the figure, Beijing time is calculated in combination with "early in the east and late in the west, east plus west minus".

(4) The angular velocity of the earth's rotation is equal at all points except the poles, which is 150/ hour, and a = b = c；; The linear speed of the earth's rotation gradually decreases from the equator to the pole to 0, with b > c > a, and the direct point of the sun moves back and forth between the Tropic of Cancer, and BC has the phenomenon of direct sunlight.

(5) The sun's rays are perpendicular to the termination line, and the earth's rotation direction is from west to east.

So the answer is:

(1) Summer solstice; Arctic polar day/Antarctic polar night.

(2) A; a； 20.

(3)6; 12; 20.

(4)A = B = C； b > C > A； BC.

(5)