When did you start counting nine cold days?

From the beginning of the solar term from winter to Sunday every year, we began to count nine, commonly known as "crossing nine", and then we entered the "counting nine cold days"

The whole process * * * has 8 1 day, of which every nine days is a unit, which is called "nine", namely 19, 29 and 39, until 99. When the Ninth Five-Year Plan ends, winter will end and warm spring will come. The custom of "Nine Numbers" originally originated in the northern region and mainly spread in the middle and lower reaches of the Yellow River.

In ancient times, the ancients thought that winter was God's punishment for people. At that time, the living conditions were poor, and the cold and warmth were relatively simple. In winter, not only some animals but also some people will freeze to death.

The method of calculating cold and warm by number nine is suitable for areas where the temperature changes obviously from winter to around in China. The calculation of temperature and warmth changes is accurate to days. Judging from the number of days from winter to Sunday, the coldest periods are "March 9 and April 9", while counting to "998 1 day" is a warm day in late spring. There are also some places that count to nine from the day of winter solstice. In some cold areas, the temperature in winter and spring is below zero degrees Celsius for a long time in the ice and snow, and the temperature change is not obvious from winter to around. "Nine days" is not much different from the temperature. For the convenience of counting nine, counting begins from the date of winter solstice, that is, the date of winter solstice is called "cross nine", every nine days is "nine nine", and so on.