What solar term starts counting nine?

The number nine is one of the traditional folk solar terms, which often refers to the ninth nine days from winter to the future, that is, 8 1 day from winter to the sun. It is extremely cold in nine seasons, which is one of the coldest periods in northern China. Its winter solstice is the first of the 24 solar terms, and it is also the shortest day and the longest night in a year.