What is folk walking on ice? What is the calendar of 79 89? How to calculate?

Haha, what you said is a proverb: 1929, don't shoot, walk on the ice in 3949, watch the willows cross the river in 5969, open the river in 79, the geese come in 89, and the cows walk everywhere in 99.

This proverb seems to be applicable to a wide range, basically applicable to all northern regions, with only a few differences in words at most. It means the phenology of "Winter Nine" days. September 19 and September 29 were too cold to raise their hands; It is colder in March and April, and the ice is thick enough for pedestrians to pass; It began to pick up on May 9 and June 9, and the distant willows are now spring; The ice of the 79 River began to melt; 89 Nanyan flies back; Spring ploughing began after the Ninth Five-Year Plan.

This algorithm is an algorithm of China lunar calendar. Every year, it starts from the winter solstice (starting from the winter solstice, which means the beginning of cold), and every nine days is a "nine", the first nine days are called "one nine", the last nine days are called "two nine", and so on until "nine nine nine", that is, the ninth nine days, until 998/kloc- At this time, winter has passed and spring has arrived. In other words, "Nine" is a concept of time. March 9 and April 9 are the coldest times of the year.