1. The vernal equinox represents a moral: day and night are almost equal. One of the 24 solar terms, March 20 or 21. On this day, the length of day and night in the northern and southern hemispheres is the same.
2. The vernal equinox, the fourth of the 24 solar terms, is an important season for farming. The sun shines directly at the earth's equator, and day and night are almost equal. In ancient times, it was spring from the beginning of spring to the end of summer, and the vernal equinox was in the middle of the three months of spring. When the sun reaches 0 degree longitude, it will meet on March 19-22 of the Gregorian calendar every year. "The vernal equinox is half Yin and half Yang. Therefore, the day and night are cold and hot." According to the lunar calendar, "Dou Zhiren is the vernal equinox, which runs before and after Sunday. The day and night in the northern and southern hemispheres are evenly divided, which is also half spring." From this day on, the direct position of the sun gradually moves northward, and the length of days and nights in the northern hemisphere changes accordingly. The northern hemisphere has longer days and shorter nights, while the southern hemisphere has the opposite.
