On January 9th, we ushered in the first day of "March Nine".
1929 did not shoot, 3949 walked on the ice, 5969 along the river to see the willow ......In North China, such a "ninety-nine song" is widely circulated, which is a vivid record of the folk custom of "counting nine".
"Counting nine" means that from the winter solstice, every nine days is counted as a "nine", and it is counted until "ninety-nine" eighty-one days, so there is also a saying of "counting nine cold days". Historically, people who have been busy for a year, recuperate in the cold winter, look forward to the arrival of spring flowers, "number nine" cold has become a joy in folk customs, in addition to word of mouth, the version of the "ninety-nine song" is slightly different in various places, there are also calligraphy, painting and other forms of the "ninety-nine cold map" and so on.
According to the average temperature statistics of the past 30 years, nearly eighty percent of the regions in China have the lowest temperature in "Sanjiu" and "Sijiu". Among them, most of the northern regions entered the coldest time of the year in "March 9".
This is because, during the winter solstice, there is still "residual heat" on the earth. During the winter solstice, the sun's rays hit the Tropic of Capricorn directly, and the solar altitude angle in the Northern Hemisphere is the smallest, making the winter solstice the shortest day and the longest night in the Northern Hemisphere. At this time, the surface of the northern hemisphere where China is located receives weak solar radiation energy, so the temperature is low.
After the winter solstice, although the solar altitude angle begins to gradually increase and the length of the daylight gradually increases, the daily heat loss from the surface is greater than the solar radiation received. This kind of energy beyond the means of making ends meet will continue until the "39" and "49", at this time, the heat budget on the surface is close to balance, and the overall "accumulated heat" on the surface is the least, and for many places in China, the lowest temperature of the year usually occurs at this time.
However, China has a vast territory, and the climate of different regions is obviously different, and the coldest period in different regions is not exactly the same. The eastern part of the Yangtze River and most of South China are colder in the "49th". Yunnan, southeastern and other places may enter the lowest temperature period of the year after the winter solstice. In China's southeast coast and Hainan Island, the lowest temperature may appear in "May Nine". On nine cold days, plants in most areas enter a dormant period, the leaves of deciduous trees fall off, and some animals begin to hibernate. And people are not idle, in agriculture,Northern RegionsIt is good to use the intermittent period of cultivated land to carry out the construction of farmland water conservancy projects, carry out ditch cleaning and drainage, plough the soil, etc., enhance the water storage and water retention capacity of cultivated land, and eliminate overwintering pests. InSouthern regionPeople also need to do a good job in the cold protection of overwintering crops to ensure the safe wintering of crops.
*: People's Digital Communication.
Editor: Xu Weichen
This mall opens today!The birth of a new landmark in the northern area of Hongkou How much do you know about the top ten news moments of Hongkou's surging economic vitality in 2023?The top ten keywords of Hongkou North Bund in 2023 are here!This year, four new commercial entities were opened!