Introduction to obliquity of the ecliptic
The yellow-corner intersection angle refers to the intersection angle of the earth's orbital plane (the ecliptic plane) and the equatorial plane (the celestial equator plane), also known as the solar declination angle or the yellow-red distance. The yellow-red intersection angle of the earth's revolution around the sun is about 23 ° 26 '. The existence of the Huang Chi intersection has important astronomical and geographical significance. It is the fundamental reason for the four seasons on the earth and the distinction between the five belts.
Due to the existence of the yellow-red intersection angle, the annual change of the direct point of the sun between the north and south latitudes of 23 ° 26 ′ of the earth causes the annual change of the noon solar height and the seasonal change of the day and night length Seasonal changes in how much solar energy is obtained in various places, thus forming a four-season replacement.
If the angle between the yellow and the red is 0 degrees, the sun will always shoot directly at the equator. The higher latitudes in the northern hemisphere will not mature due to insufficient heat, and the cropping boundary will move south.