Geography: The south of China is darker than the north, isn't it?

In summer, the sun shines directly into the northern hemisphere, and the daytime in the northern hemisphere is longer. The daytime in the Arctic Circle is 24 hours, and the equator is always 12 hour. Therefore, in summer, the north of China is darker than the south, and in winter, the sun shines directly into the south, so contrary to the above, the south is darker than the north.

In the Spring and Autumn Period, the global day length is 12 hours, the sunrise is at 6 o'clock, and the sunset is at 18 hours, which is at the same longitude as the local time, so the sunrise and sunset are at the same time in the same longitude.

Extended data:

Daily variation law

The reason for the change of the length of day and night is that the earth axis tilts and the earth rotates, pointing to the vicinity of Polaris.

In the process of the earth's revolution around the sun, the earth's axis always has an inclination angle of 66 degrees and 34 minutes with the orbital plane. Due to the inclination of the earth's axis, the height of the sun at different positions on the earth's surface is different when the earth is in different positions in its orbit.

When the sun is high, the sun shines directly and the heat is concentrated, just like facing a stove; Moreover, the path of the sun in the air is long, the sunshine time is long, the days are long and the nights are short, and the temperature is bound to be high. It's summer.

On the contrary, when the height of the sun is small, the sun shines obliquely on the ground, and the heat is dispersed, which is equivalent to leaning on the stove; Moreover, the path of the sun in the air is short, the sunshine time is short, the days are short and the nights are long, and the temperature is low; From winter to summer, the height of the sun changes from low to high. Similarly, the change of sun height affects the length of day and night and the temperature, forming autumn and spring respectively.

Because the earth never stops sideways and revolves around the sun, this kind of cold and warm will keep alternating, thus forming four seasons.

Under the irradiation of the sun, the earth is divided into two hemispheres: the hemisphere facing the sun is the day hemisphere and the hemisphere facing away from the sun is the night hemisphere. The dividing line between the two hemispheres, called the terminator line, is a great circle of the earth. The place where the dusk circle passes is experiencing the morning or dusk of a day. The sun seen there is on the horizon in the east or west.

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