What is the sun's altitude angle at the vernal equinox, summer solstice, autumn equinox and winter solstice in Beijing?

Sun height at noon in Beijing = 90-| 40-(-23 26') | = 26 34' Summer solstice = 90-| 40-23 26' | = 73 26'

At noon in Beijing at the vernal equinox, the sun height is 90-| 40-0 | = 50?

So is the vernal equinox, because the sun shines directly on the equator at the vernal equinox?

Beijing is located at 40 north latitude, and the sun's direct point is at the equator in the spring and autumn, so the latitude of the sun's direct point is zero. The summer solstice is 23 degrees 26 minutes north latitude, and so is the winter solstice, but the winter solstice is 23 degrees 26 minutes south latitude.

The solar altitude angle (α) at a certain moment in a certain place = 90-(local latitude-latitude of the direct point of the sun). (Note: North latitude is positive and South latitude is negative)

At noon, the solar altitude angle is 12, which is the included angle between the sun's rays and the ground. The closer to the direct point of the sun, the greater the altitude angle of the sun.

The law of motion from the bisector of the sun to the direct point of the sun;

Equinox: The sun shines directly at the equator, and the altitude angle of the sun gradually decreases from the equator to the north and south poles at noon. After that, the point of direct sunlight slowly moves northward and reaches the northernmost point of direct sunlight-the Tropic of Cancer in summer solstice.

Summer solstice: at noon, the height angle of the sun decreases from the tropic of cancer to the north and south poles.

The direct point of the sun moves south again, returns to the equator at the autumnal equinox, continues to move south after the autumnal equinox, and reaches the tropic of cancer at the winter solstice.

Winter solstice: At noon, the altitude angle of the sun gradually decreases from the tropic of Capricorn to the north and south poles.