What does the vernal equinox mean? What are the solar terms?

The vernal equinox is the midpoint of 90 days in spring. Every year on March 20th of the Gregorian calendar, when the sun is at 0 (vernal equinox) of the Yellow Meridian. On the vernal equinox, the sun shines directly at the equator of the earth, and the seasons in the northern and southern hemispheres are opposite. The northern hemisphere is the vernal equinox and the southern hemisphere is the autumnal equinox.

The vernal equinox is one of the 24 solar terms and a traditional festival. In the Zhou dynasty, there was a ceremony to worship the sun at the vernal equinox. Book of Rites: "Altar." Confucius' Ying Da Shu: "Also called the vernal equinox." This custom has been handed down from generation to generation. On the day of vernal equinox, the sun shines directly on the equator, and the length of day and night is almost equal, which is exactly half of the 90th day of spring, so it is called "vernal equinox". After that, the direct sunlight position gradually moved northward, and the days began to get longer and the nights began to get shorter.

Extended data:

The vernal equinox is an important solar term, which not only has astronomical significance: the northern and southern hemispheres are equally divided day and night, but also has obvious characteristics in climate. At the vernal equinox, except the Qinghai-Tibet Plateau, the northeast, the northwest and the northern part of North China, China entered a beautiful spring.

During the vernal equinox, the daily average temperature in all parts of China rose steadily to above 0℃ except the alpine mountain area and the area north of 45 north latitude. At this time, the cold has passed and the temperature has risen rapidly, especially in North China and Huanghuai Plain. The daily average temperature rises to above 10℃ almost at the same time as the rainy areas along the Yangtze River and the south of the Yangtze River, entering a bright spring. On the vast land, on the bank of willow green, the grass grows in Fei Ying, the wheat is jointing, the rape blossoms are fragrant, the peach blossoms are red, the plum blossoms are yellow, and South China is a scene of late spring.

References:

Equinox-Baidu Encyclopedia