Examples of judging solar terms by orbital revolution

Summer solstice? Autumn equinox? Winter solstice? Spring Equinox

(2) gradually decreasing from the tropic of Capricorn to both sides.

(3) The days get longer?

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

Test and analysis: (1) According to the latitude position of the sun's direct point, if the sun's direct point at position A is located on the tropic of cancer, it is determined as the summer solstice in the northern hemisphere; The direct point of the sun at position C is located on the tropic of Capricorn, and it is judged as the winter solstice; From the direction of the earth's revolution, B is the autumnal equinox and D is the vernal equinox. (2) Combined with the above conclusions, position C indicates the winter solstice, the direct point of the sun is located on the tropic of Capricorn, and the latitude distribution law of the noon sun height is decreasing from the direct point of the sun to the north and south sides. (3) From D to A, from vernal equinox to summer solstice, when the direct point of the sun moves northward, the days in the northern hemisphere become longer and the nights become shorter. (4) From A to B, that is, from summer solstice to autumnal equinox, the revolution speed first slows down and then becomes faster.

Comments: This question is generally difficult, and it belongs to the basic test questions of earth movement. Students should pay attention to the following points: ① On the orbit diagram of revolution, judge the bisector of the sun according to the latitude position of the direct point of the sun; ② According to the position and movement of the direct point of the sun, judge the length of day and night and the change of the height of the sun at noon; (3) According to the positional relationship between the earth's orbit and perihelion and apohelion, judge the change of the earth's orbit speed. For the test questions of the earth movement, students should sort out and summarize the basic methods and laws of solving problems in their usual study.