Twenty-four solar terms and direct sunlight

Schematic diagram of the sun shining on the earth from winter solstice: plane, side and top view;

The direct point of the sun is the point where the incident angle of sunlight on the earth's surface (that is, the solar altitude angle) is 90 degrees, and it is the intersection of the connecting line between the center of the earth and the sun and the spherical surface of the earth. The meridian where the direct point of the sun is located is 12 noon.

The law of activity is: at the vernal equinox (March 2 1 or so), the direct point of the sun is at the equator (0), and then it moves north. During the summer solstice (around June 22nd), the direct point of the sun is on the tropic of cancer (23 26 ′ N), and then moves south.

At the autumnal equinox (around September 23rd), the direct point of the sun is at the equator (0), and then it continues to move south. During the winter solstice (around 65438+February 22nd), the direct point of the sun is on the tropic of Capricorn (23 26), and then moves northward.

Geographical significance:

1. The movement of the direct point of the sun causes the change of global heat distribution. 2. The seasonal movement of the direct point of the sun drives the north-south movement of the planetary system.

3. The seasonal movement of the direct point of the sun causes the change of the length of day and night and the height of the sun at noon.