When did extreme day and night appear in the south of Antarctic Circle and north of Arctic Circle?
The formation of day and night is mainly because the earth is an opaque sphere. The sunny side of the earth is daytime, and the sunny side is night. Due to the rotation of the earth, the sunny side and the sunny side alternate constantly, forming a phenomenon of alternating day and night. The hemisphere irradiated by the sun is called the day hemisphere, the hemisphere not irradiated by the sun is called the night hemisphere, and the dividing line (circle) between the day hemisphere and the night hemisphere is called the termination line. The terminator line divides the latitude into day arc and night arc. On the equator, the solar arc and the night arc are always equal. Every year on March 2 1 day (vernal equinox in the northern hemisphere) and September 23 (vernal equinox in the northern hemisphere), the sun shines directly on the equator, and the global solar arc and night arc are equal in length, and the time between day and night is equal, each being 12 hour. In addition, the length of day arc and night arc is equal everywhere. That is, the time between day and night is not equal. March 2 1 to September 23 is the summer half year in the northern hemisphere. The solar arc at all latitudes is longer than the night arc, and the day is longer than the night. The higher the latitude, the longer the day and the shorter the night. Around the North Pole, the sun never sets all day, which is called extreme day. This is the winter half year in the southern hemisphere, which is completely opposite to the northern hemisphere. The night is long and short, around the South Pole. On this day, the northern hemisphere has the longest day and the shortest night, the southern hemisphere has the longest day and the shortest night, and the south of the Antarctic circle is full of polar nights. From September 23rd to March the following year, 2 1 is the winter half year in the northern hemisphere, with short days and long nights in all parts of the northern hemisphere. The higher the latitude, the shorter the day and the longer the night, and the polar night appears around the North Pole. At this time, it is the southern hemisphere. Extreme days appear around the South Pole. 65438+February 22nd is the winter solstice in the northern hemisphere. On this day, the northern hemisphere has the shortest day and the longest night, and the Arctic Circle is full of extreme night phenomena. On the other hand, the southern hemisphere has the longest day and the shortest night, and the Antarctic circle is full of extreme daytime phenomena.