Winter Solstice "Nine Days"｜When you count to ninety-nine days, will spring come?

The winter solstice has arrived, which means we have entered the "Nine Days" season. In traditional Chinese culture, nine days is a way to count the number of cold days in winter. Starting from the winter solstice, every nine days is counted as a "nine", and when the nine nine days are counted to eighty-one days, spring is here.

Water plants on the surface of Prajna Lake in Houjiazhai Township, Zunhua City, Hebei Province are frozen (Photo source: Xinhua News Agency)

01The Origin of the Nine-Nine Days Custom

There is no exact record of the origin of the custom of counting the nine cold days in winter, but people have used the method of counting the nine cold days in winter since long ago.

In traditional Chinese culture, nine is regarded as the number of "extreme yang" and also the greatest number. The accumulation of nine "extreme yang numbers" means that the yin energy is gradually decreasing. When it accumulates to nine times, it has reached its end, representing the natural law that cold goes away and warmth comes, and yin disappears and yang grows. Therefore, the ancients chose to use "nine" as the unit for counting nine days. So, are there any interesting ways to "count nine days"? Many people's first impression is the nine-nine song, which we have already talked about in detail last year, so I will not repeat it here. In fact, in addition to the "nine-nine song", there are many other interesting forms.

Frost covers wheat seedlings in Wen County, Jiaozuo City, Henan Province (Photo source: Xinhua News Agency)

02 The ancients’ fancy “ Nine Days ”

♦ Jiujiu Xiaohan Diagram

Jiujiu Xiaohantu originated in the Ming Dynasty and was mainly circulated among scholars in northern China. It is not only a way to record the weather, but also an art form to express the mood of welcoming spring. Jiujiu Xiaohantu mainly has circle and plum blossom patterns .

Circle type : Divide the rice paper into nine equal squares, and use the pen cap to dip ink to print nine circles on each square, filling one circle every day. The filling rule is usually to paint cloudy on the top, sunny on the bottom, windy on the left, and rainy and snowy on the right.

Plum blossom pattern : Draw nine branches of winter plum blossoms on white paper, with nine flowers on each branch, one branch corresponds to nine, and one flower corresponds to one day. It is also called "Ya Tu".

By drawing the Jiujiu Xiaohantu, people can not only intuitively feel the change of seasons, but also find a kind of sustenance and fun in the long winter.

Blooming plum blossoms (Photo source: Xinhuanet)

♦Write Nine

The custom of "writing nine" originated in the Qing Dynasty. It was mainly implemented in the palace and later gradually spread to the people. The rise of this custom is closely related to Emperor Daoguang of the Qing Dynasty. It is said that one winter solstice, Emperor Daoguang wrote nine characters on a banner: "The weeping willows in front of the courtyard (pavilion) wait for the spring breeze carefully." Because each character is written in traditional Chinese, there are nine strokes in total for the nine characters. Later, Emperor Daoguang ordered that each character be hooked into a hollow character and posted on the wall. Starting from the winter solstice, he ordered people to fill in one stroke with ink every day. When every character on the Jiujiu Xiaohan Diagram was filled in, it was the time of spring.

There are some additional rules in the writing process. For example, after filling in one stroke each day, a thin brush is used to fill in the thick stroke with white to record the weather conditions of the day. Therefore, a line of "write nine" is also a more detailed meteorological data for the ninety-nine days.

"Writing Nine" is not only a word game, but also a way to record the weather. By recording the weather conditions every day, people can more intuitively feel the change of seasons and weather. And with the writing of one stroke every day, people seem to be able to feel the breath of spring getting closer.

Snow falls on red maples at Zijin Mountain in Nanjing, Jiangsu Province. (Photo: Xinhua News Agency)

0 3Is “Counting the Nine Days” really scientific?

The principle of the Nine Days is that the winter solstice is the turning point of the sun's southward movement . On this day, the sun's rays directly hit the Tropic of Capricorn, and it is the day with the shortest day and longest night in the northern hemisphere. From this day on, the days in the northern hemisphere gradually get longer and the nights gradually get shorter, but because the angle between the direct angle of the sun and the ground increases slowly, the daily heat balance on the ground is still in a deficit state, so the temperature continues to drop until it reaches the coldest on the 39th and 49th days of the winter solstice, and then gradually warms up. People divide the 81 days after the winter solstice into nine stages to represent the weather changes after the winter solstice.

During the nine-day period, people can observe the gradual change of temperature. For example, during the first and second nine-day periods, the temperature begins to gradually decrease, and people will feel that the weather is getting colder and colder; during the third and fourth nine-day periods, the temperature reaches its lowest point, which is also the coldest period of the year; then, with the arrival of the fifth and sixth nine-day periods, the temperature begins to gradually rise, and the weather gradually becomes warmer; during the seventh and eighth nine-day periods, the temperature has risen to a more comfortable level, and migratory birds such as geese have begun to return north; finally, during the ninth nine-day period, the temperature has basically stabilized, spring is warm, flowers are blooming, and all things are reviving.

From the perspective of modern science, the scientific nature of the Nine Days of Winter has been further explained. After the winter solstice, although the daytime hours are getting longer, the rate of increase is very slow. The daily heat expenditure of the ground is greater than the absorption, so it continues to lose heat and the ground temperature continues to drop. This process is consistent with the phenomenon of gradually decreasing temperatures during the "First Nine Days" and "Second Nine Days" described in the Nine Days of Winter. At the same time, as the angle between the direct sunlight and the ground increases and the daily heat expenditure on the ground gradually balances, the temperature also begins to gradually rise, which is consistent with the phenomenon of rising temperatures during the "Fifth Nine Days" and "Sixth Nine Days" described in the Nine Days of Winter.

Author: Wang Yuanhong, Senior Weather and Climate Engineer

Reviewer: Song Yuanming Associate Professor, Institute of History of Science and Cultural Heritage, University of Science and Technology Beijing, Deputy Director of Institute of Science, Technology and Culture

Produced by: Science Popularization China

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