Why is there no day in the Arctic during the winter solstice?

Due to the polar night phenomenon of the Arctic winter solstice, the sun moved to the Tropic of Capricorn, and sunlight could not reach the Arctic. There will be an extreme night at the North Pole. The polar night in the Arctic (or the polar day in the Antarctic) begins at the autumnal equinox and ends at the vernal equinox, and lasts about 179 days. The maximum dividing line between polar day and polar night is on the latitude line of 66 34'. The ideal conditions of these situations are: ① the sun is a point light source; (2) The sunlight goes straight ahead; The earth is a regular sphere. But this is not the case. (d) The sun is not a point light source, but a circular light source with an apparent radius of 16'; (2) Because the atmosphere refracts light, sunlight does not travel in a straight line when it passes through the earth's atmosphere. However, there is an angular deviation, which is the largest when the sun is close to the horizon (that is, the height of the sun is about 0), and the deviation angle is 34'; ③ The earth is not a regular sphere, but an approximate elliptical sphere with a polar radius of about 6357km and an equatorial radius of about 6378km. For ① and ②, they not only affect the starting and ending time and duration of polar day and night, but also affect the range of polar day and night in polar regions. Ideally, the day and night hemispheres on the earth are equally divided, but the apparent radius of the sun is 65,438+06', and the light at the edge of the sun can reach 65,438+06' across the solar hemisphere, which makes the solar hemisphere expand around 65,438+06'. At the same time, due to the refraction of sunlight by the atmosphere, when the sun approaches the horizon of the edge of the daytime hemisphere, the angle deviation of sunlight is 34', which makes the daytime hemisphere expand around by 34'. Source: Middle School Political History Geography Teaching Guidance Edition