Why does Tomb-Sweeping Day calculate according to the solar calendar?

1. The lunar calendar in China is a combination of yin and yang. Tomb-Sweeping Day is the "Tomb-Sweeping Day" in China's 24 solar terms, and the solar terms reflect the solar calendar in the lunar calendar, so Tomb-Sweeping Day usually has three days, from April 4th to April 6th.

2. The Qingming solar calendar generally changes from April 4 to 6, and it is not fixed on a certain day, but the fifth day is the most common. Because the length of a year is determined by the movement of the sun, and the 24 solar terms are also determined by the apparent position of the sun, basically the date of each solar term will not change much every year.

3. The postponement of solar terms will sometimes make a solar term pass midnight and arrive the next day; One more leap year will also change the solar terms. Of course, no matter how it changes, the date difference of solar terms will only be within 3 days.

Extended data:

Customs in Tomb-Sweeping Day:

1. The custom of ancestor worship in Tomb-Sweeping Day has been inherited from generation to generation and has become a fixed custom of the Chinese nation. Although the custom of forbidding fire and eating cold food in Tomb-Sweeping Day became a national folk custom only in the Song Dynasty, the custom of sweeping graves to worship ancestors in Tomb-Sweeping Day has a long history.

2. In addition to visiting graves, the custom of Tomb-Sweeping Day has absorbed a series of folk sports activities such as swinging, cuju, polo and willow planting in its historical development.

References:

Baidu Encyclopedia: Tomb-Sweeping Day;

People's Daily Online: They all say "the fourth and fifth Qingming Festival". Why is Qingming on April 4th this year?