What is the origin of the vernal equinox solar terms?

1, vernal equinox, March 20th or 2 1 in Gregorian calendar every year, when the sun reaches 0 degrees (vernal equinox). The length of day and night is average, just half of the 90th day of spring, so it is called "vernal equinox".

On the day of vernal equinox, the sun shines directly on the equator, and day and night are almost equal. After that, the direct sunlight position gradually moved northward, and the days were long and the nights were short.

3. 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; Climatically, there are also obvious characteristics. During the spring equinox, China has entered a beautiful spring scenery except the Qinghai-Tibet Plateau, Northeast China, Northwest China and North China. On the vast land, willows are green, Fei Ying grass grows, wheat jointing and rape blossoms are fragrant.