Where does the sun shine on the earth at the spring equinox, summer solstice, autumnal equinox and winter solstice?

The direct sunlight point on the vernal and autumnal equinoxes is on the equator, the direct sunlight point on the summer solstice is on the Tropic of Cancer, and the direct sunlight point on the winter solstice is on the Tropic of Cancer.

The earth's revolution and rotation form the yellow-red angle, which produces periodic changes in the sun's direct point between the north and south Tropics of Cancer, thus forming periodic changes in climate, day and night length, and solar height.

Summer is the season of the year with the longest days and the highest altitude of the sun at noon. Take the Beginning of Spring (February 4 or 5), Beginning of Summer (May 5 or 6), Beginning of Autumn (August 7 or 8), and Beginning of Winter (November 7 or 8) among the 24 solar terms as the starting point. .

The movement of the earth in its orbit will produce regular changes in weather and seasons. In traditional agriculture, farmers carry out agricultural production accordingly, as in the proverb: "Plant melons and beans before and after Grain Rain."

The yellow-red angle is the direct cause that affects the astronomical seasons. This is because:

The distribution of the height of the sun at noon with latitude is: large at low latitudes and small at high latitudes, with spring and autumn equinoxing, decreasing from the equator to the poles; on the summer solstice, decreasing from the Tropic of Cancer to the north and south; on the winter solstice , decreasing from the Tropic of Capricorn to the north and south sides.

The seasonal changes are as follows: north of the Tropic of Cancer, the height of the sun reaches its maximum value at noon before and after the summer solstice, and reaches its minimum value before and after the winter solstice. The opposite is true south of the Tropic of Capricorn. In the area between the Tropic of Cancer and the Tropic of Cancer, the sun shines directly twice a year.