At the age of 30, the spring is over, and the world is fragrant.

From the twenty-four solar terms-vernal equinox.

The vernal equinox is the fourth solar term in spring, which falls on March 19-22 of the Gregorian calendar every year. "Twenty-four solar terms" explains: "In mid-February, it is half of 90 days, so it is called minutes." Therefore, the vernal equinox was also called "Japan-China", "Day and Night Equinox" and "Midspring Moon" in ancient times. "Equinox" has two meanings. One is "season sharing". Traditionally, spring is between beginning of spring and Changchun, and the vernal equinox is in the middle of the two solar terms, which just divides spring equally. Another meaning is "equal day and night". At the vernal equinox, the sun shines directly on the equator, and the length of day and night is equal, each being 12 hour. The climate of the vernal equinox is characterized by warm and sunny weather.