Bai Juyi's vernal equinox poems describe several kinds of flowers.
The vernal equinox refers to one of the 24 solar terms, that is, when the sun is located at 0 degrees of the yellow meridian (vernal equinox). Gregorian calendar March 20th or March 2nd1day.
Every year on March 2 1 day of Gregorian calendar, when the sun is located at 0 (vernal equinox) of the yellow meridian, it is the vernal equinox. On this day, the sun shines almost directly on the equator of the earth, and the whole world is almost as long as day and night (regardless of the refraction of sunlight by the atmosphere and the shadow in the morning). After the vernal equinox, the direct point of the sun continued to move from the equator to the northern hemisphere, and the northern hemisphere began to have long days and short nights (long days and short nights), while the southern hemisphere began to have short days and short nights (short days and short nights). Therefore, the vernal equinox is also called the ascending equinox.
The vernal equinox was also called "Japan-China", "Day and Night Equinox" and "Midspring Moon" in ancient times. "Li Mingshi Yi" said: "The dividing line, the turn of Huang Chi, the sun stops here, and the day and night are equally divided." Therefore, the significance of the vernal equinox, first, refers to the equal division of day and night, each of which is 12 hours; Second, in ancient times, it was spring from beginning of spring to long summer, and the vernal equinox happened to be in the three months of spring, and spring was equally divided.