"Spring rain surprises spring and clear valley days, summer is full of blindness and heat, autumn dew and frost, winter snow and snow."

Chun Er: The beginning of spring and the vernal equinox.

Summer: the long summer, the summer solstice.

Qiu Er: The beginning of autumn and vernal equinox.

The second winter: beginning of winter, the solstice winter.

Solar terms refer to the twenty-four solar terms, which is a supplementary calendar formulated by China in ancient times to guide farming, and is the crystallization of the long-term experience and wisdom of the working people of the Chinese nation.

Since China was an agricultural society in ancient times, agriculture needed to have a strict understanding of the operation of the sun, and farming was carried out entirely according to the sun. Therefore, the "twenty-four solar terms" that reflect the solar cycle alone are added to the calendar as the standard for determining leap months.

China's orthodox 24 solar terms are based on Henan. China's lunar calendar is a combination of yin and yang, which is based on the movement of the sun and the moon, so adding 24 solar terms can better reflect the cycle of the sun's movement.