1, why is extreme day and night a range?

1. I don't know what you mean by range. The area of extreme day and night in the world changes every day. On the autumnal equinox, the sun shines directly on the equator, and the length of day and night is equal all over the world. On the second day of the autumnal equinox, the direct point of the sun began to move to the tropic of Capricorn, and the polar night appeared in the North Pole. Until the winter solstice, the sun's direct point directly hits the Tropic of Capricorn, and the area within the Arctic Circle appears extreme night phenomenon. From the autumnal equinox to the winter solstice, the polar night area extends from the North Pole to the Arctic Circle. After the winter solstice, the direct point of the sun moved from the tropic of Capricorn to the equator, and it did not return to the equator until the vernal equinox of the following year. During this period, the polar night area gradually shrinks from the Arctic Circle to the North Pole until it disappears (the vernal equinox is as long as day and night). Similarly, during the spring equinox to autumn equinox in the same year, the extreme day phenomenon in the northern hemisphere will also undergo the same evolution.

Although the direct point of the sun does not directly point to the pole, there will still be extreme days and nights. This is because the earth axis is not perpendicular to the ecliptic plane. The equatorial plane and the ecliptic plane (the only plane formed by the earth's orbit and the sun) form an included angle of 23 degrees and 26 minutes. The earth revolves around its axis. The earth's axis is not perpendicular to the ecliptic, but inclined. As you can imagine, at any time of the year, the area of the earth exposed to sunlight is the same, which is equal to half of the earth. It is precisely because of the tilt of the earth's axis that some areas of the earth cannot be exposed to the sun for a day, no matter how they rotate. So the polar night was born.

3. The pole is only at the vernal equinox and the autumnal equinox, and there is no extreme day and night.

During the winter solstice, the day length in the Arctic circle is zero, while the day length in the Antarctic circle is 24 hours. The length of day between two circles decreases from south to north.

As can be seen from the figure, the length of the day = the ratio of the length of the solar arc to the latitude perimeter X24.

As for the formula, it is more difficult. If you are really interested in geography, you can study it, but if it's just to cope with the exam, it's enough if you can understand what I said above. ? Although I am not a geography major, I have a strong interest in geography. I once dreamed of becoming a geological exploration team member and going to the motherland to explore treasures. But because of my parents' opposition, I have to engage in the pharmaceutical industry. I believe that as long as you are interested, you will certainly learn something. I see that you are eager to learn and curious, so I spent some time answering your questions. I hope it helps you.