Is the temperature the lowest in “March 9”?

Is the temperature the lowest in “March 9”?

On January 9th, we ushered in the first day of the “March 9th” holiday. “1929 did not take action, 3949 walked on the ice, 5969 watched the willows along the river…” In North China, this kind of “Nine-Nine Song” is widely circulated, which is exactly the folk “Counting Nine”. A vivid record of a custom.

“Counting nine” means counting from the winter solstice, counting one “nine” every nine days until “nine-nine” is eighty-one days, so there is also the saying “counting nine cold days”. Historically, people who have been busy for a year recuperate in the cold winter and look forward to the arrival of spring. “Counting nine” to relieve the cold has become a joy in folk customs. In addition to word of mouth, there are slightly different versions in different places. The “Nine-Nine Songs” and the “Nine-Nine Cold-repelling Pictures” that have been handed down in the form of calligraphy, painting, etc.

According to average temperature statistics in the past 30 years, nearly 80% of areas in my country have the lowest temperatures during the “39” and “49” periods. Among them, most of the northern regions enter the coldest time of the year during March 9th.

This is because during the winter solstice, the earth still has “residual heat”. During the winter solstice, the sun shines directly on the Tropic of Capricorn, and the solar altitude angle in the northern hemisphere is the smallest. This makes the winter solstice the day with the shortest day and the longest night in the northern hemisphere. At this time, the surface of the northern hemisphere where our country 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 day gradually increases, the heat lost by the surface every day is greater than the solar radiation received. This situation of being unable to make ends meet will continue until the “Third and Fourth” periods. At this time, the heat budget of the earth’s surface is close to balance, and the overall “heat accumulation” of the earth’s surface is the least. For many places in our country, the lowest temperature of the year is Usually occurs at this time.

However, our country has a vast territory, and the climate in different regions has obvious differences. The coldest periods in different regions are not exactly the same. Eastern Jiangnan, most of South China and other places will be colder during the “49th”. Yunnan, southeastern Tibet and other places may enter the lowest temperature period of the year after the winter solstice. In places such as the southeastern coast of my country and Hainan Island, the lowest temperature period may occur during May 9th.

During the cold weather, plants in most areas enter the dormant period, leaves of deciduous trees fall off, and some animals begin to hibernate. And people will not be idle. In terms of agriculture, the northern region takes advantage of the intermission period of cultivated land to carry out farmland water conservancy project construction, clearing ditches and drainage, plowing and plowing the soil, etc., to enhance the water storage and retention capacity of cultivated land, and to eliminate overwintering pests. In the southern region, people also need to carefully protect overwintering crops from cold to ensure that crops survive the winter safely.

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