Cyclic solar terms

(1) According to the direction of the earth's axis, the direction of the earth's revolution and the position at four o'clock, it can be judged that A is the summer solstice, B is the autumnal equinox, C is the winter solstice and D is the vernal equinox.

(2)A is the summer solstice, and the sun shines directly on the Tropic of Cancer; B is the autumnal equinox, and the sun shines directly on the equator; C is the winter solstice, and the sun shines directly on the tropic of Capricorn; D is the vernal equinox, and the sun shines directly on the equator. The sun's direct point moves back and forth between the tropic of cancer, and the sun's direct point moves north with D→A and C → D. 。

(3)D is the vernal equinox, the sun shines directly on the equator, A is the summer solstice, and the sun shines directly on the Tropic of Cancer. During the revolution of the earth from D to A, the sun shines directly into the northern hemisphere and moves northward. The change of daytime length in Qinhuangdao is that the daytime is long, the night is short and the daytime is longer.

(4)A is the summer solstice, the sun shines directly on the Tropic of Cancer, B is the autumnal equinox, and the sun shines directly on the equator. In the process of the earth's revolution from place A to place B, the speed of the earth's revolution is the slowest in early July, first slow and then fast.

So the answer is:

(1) Summer solstice; Autumnal equinox; Solstice of winter; Spring Equinox

(2)D→A、C→D。

(3) The days are getting longer and longer.

(4) Slow down first, then get up quickly.