The extended duration of sunshine each day starting from the winter solstice

Starting from the winter solstice, the position of direct sunlight moves northward, and the days gradually lengthen, with the average daylight length increasing by more than 90 seconds per day.

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Winter Solstice

The winter solstice is a solar term divided according to astronomy. In ancient times, it was called "short day" and "short day solstice". On the winter solstice, the sun is located at 270 degrees longitude, and the sun shines almost directly on the Tropic of Capricorn. It is the shortest day of the year in the northern hemisphere. There are less than 10 hours between sunrise and sunset in various parts of our province. After the winter solstice, as the earth moves in its orbit around the sun, the direct sunlight zone gradually moves northward, causing the days in the northern hemisphere to lengthen and the nights to shorten. Although the sun has the lowest altitude and the shortest sunshine time on the winter solstice, the heat absorbed by the ground is less than the heat lost. However, the heat accumulated on the ground for a long time in the past continues to be lost, and the temperature near the ground has not yet dropped to the lowest, so it is not yet a day. The coldest time of the year. After the winter solstice, although the days are getting longer and the nights are getting shorter, in the short term the days are still short and the nights are long. The heat absorbed by the ground every day is still less than the heat lost, so the temperature does not immediately rise. It is customary among the masses to "count nine" since the winter solstice, and every nine days is a "nine". Around March 9th, the heat accumulated on the ground is the least and the weather is the coldest, so it is said that "the cold is on March 9th". Astronomy regards the winter solstice as the beginning of winter, which is obviously too late for most areas in our country. During the winter solstice, the average temperature in the Western Sichuan Plateau is generally below 0°C, and in the Sichuan Basin it is only around 6°C to 8°C. However, in the low-altitude river valleys of southwestern Sichuan, even in early January, the coldest time in the area, the average temperature is still above 10°C. It can be said that autumn is replaced by spring and there is no winter all year round.

The winter solstice means that severe winter has arrived. "Collection and Explanation of the Seventy-Two Hours of the Moon Order": "The energy stored in the end reaches its peak at this point." "Tongwei Xiaojing Yuanshen Deed" records: "The yang begins to arrive at the yin pole, and the sun reaches the south, and gradually grows to the end." It begins every year around December 22 of the solar calendar when the sun reaches 270 degrees of celestial longitude. At this time, the sun almost shines directly on the Tropic of Capricorn, rises late in the morning, and sets in a low arc in the southern half of the sky, so the daytime in the northern hemisphere is the shortest.

However, the motherland has a vast territory. Although the day is the shortest at this time, it is also very short: in Shantou, Guangzhou and other places near the Tropic of Cancer, the day is about 11 hours and 31 minutes; north latitude is about 40 degrees In Qinhuangdao, Beijing, Jiayuguan, Kashgar and other places, the daylight hours are about 10 hours and 20 minutes; in the northernmost Mohe Town, the daylight hours are less than 7 hours. The farmer's proverb "It's unclear when you travel a hundred miles in winter, but it's dark when you travel hundreds of miles in summer." This illustrates the huge difference between day and night in the winter solstice and the summer solstice.

"After winter, a needle grows", "After eating the winter solstice rice, a needle grows every day". Starting from the winter solstice, the position of direct sunlight moves northward and the days gradually lengthen, with the average daylight length increasing by more than 90 seconds per day. At the winter solstice, because the heat radiated from the sun to the ground is still less than the heat emitted from the ground to the air, the temperature continues to drop in the short term. Astronomy stipulates that the winter solstice is the beginning of winter in the northern hemisphere.

As we mentioned before, the beginning of winter means the arrival of winter. Why is it said here that the winter solstice is the beginning of winter in the northern hemisphere? These are two different concepts: one is "arrival" and the other is "beginning". As we all know, the northern hemisphere where we live is exactly the opposite of the southern hemisphere: we have the winter solstice, they have the summer solstice; we have the autumnal equinox, they have the spring equinox; we have winter, they have summer, we have spring, summer, autumn and winter, they have autumn, winter and spring and summer. Therefore, starting from the entire earth, the severe winter in our northern hemisphere begins with the winter solstice. The agricultural proverb "Winter Solstice is not cold" also explains this truth.

The winter solstice, calculated from the earth’s orbit around the sun, is the coldest solar term in the year. However, people feel that it is not as cold as the minor cold. So what’s going on? It turns out that before the winter solstice, summer and autumn passed, and the ground There is a lot of heat accumulated. Until the winter solstice, the heat accumulated on the ground can continue to compensate for the lack of heat absorption during the day, so the temperature near the ground has not dropped to the lowest.

The ancients called the winter solstice "Winter Festival", also called "Winter Festival" and "New Year Festival". On this day, ancient emperors led their civil and military courtiers out of the suburbs to worship their ancestors. After the ceremony, mutual worship in the court was held. By the Qing Dynasty, the "Winter Solstice" was designated as the day for worshiping ancestors and visiting their graves.

Counting nine begins on the day of the winter solstice. This is what people call "counting nine in advance of winter." Counting nine days is one nine, counting another nine days is twenty-nine... When you count to "nine-nine", it means that "nine" is exhausted, and "nine-nine is exhausted, and the poplars bloom", and then the weather will be warm.

People say that "cold comes in nine and heat comes in." Although the number nine is cold, due to the vast territory of our country, the cold is also different: the "Nine-Nine Song" in the middle and lower reaches of the Yellow River is: One Nine Twenty-nine don't take action; three-nine, four-nine, walk on the river; five-nine, six-nine, look at the willows along the river; seven-nine, the river opens, and the geese come; nine-nine and one nine, the cattle are everywhere.

Jiangnan's "Nine-Nine Songs" are: One thousand nine hundred and twenty-nine, we meet each other and we can't make a move; three-nine and twenty-seven, the bamboo basket is played on the fence (an ancient musical instrument, which means the sound of the fence crackling in the cold wind); forty-nine Thirty-six, the night is like a heron (the night is cold like a white crane curling up to sleep); Five-nine-forty-five, the sun opens the door; Six-nine-fifty-four, the poor strive for spirit; Seven-nine-sixty-three, the cloth sleeves are carried The first load; eighty-nine seventy-two, the cat seeks the sunny land; ninety-nine eighty-one, the plow and rake come out together. The coldest are 39 and 49. In Jilin: 3949 dogs freeze to death, while in Jiangsu it is "3949 old men walking around picking up excrement". It can be seen that the temperature is very different.

At the winter solstice, it is necessary to do a good job in overwintering livestock, repair pens, plug holes, hang straw curtains on pen doors, feed and drink livestock well, so that they can survive the winter safely.

Heavy snowfall and winter solstice both fall in December of the Gregorian calendar. Farming activities are summarized as follows:

Shanxi: Farming in winter solstice focuses on accumulating fertilizer, and wheat grinding and winter watering are in season. Preparing livestock for cold protection early, applying warm ditch fertilizer to cultivate art gardens. Shandong: On the ninth day of the winter solstice, the weather is cold, so weaving mats and baskets are a popular sideline business. Hebei: It snows heavily during the winter solstice, the ground freezes and the rivers close, the wheat seedlings are watered with urine, and the snow is pressed and the ice is moved. Winter water conservancy repairs should be carried out as soon as possible. The earth will be transported to the fence and the fence will be repaired. Strengthen feeding and protect livestock for the winter. Xinjiang: Heavy snowfall in December, the severe cold season has arrived. The ground is frozen and the snow is solid, it’s a good time to accumulate fertilizer and transport it. Use idle water to water the white ground, and frequently turn the cellars for winter storage vegetables. Jiangsu: Heavy snow makes the river muddy, and the river is sealed tightly during the winter solstice. The leisure time in winter becomes busy in winter, with dams being built and fields renovated. Shanghai: After the heavy snow, the winter solstice continues, water conservancy projects are built to seize fertilizer sources; side businesses are carried out to flatten the land, and summaries and evaluations are made to welcome the new year. Anhui: The snowy days have become cold, and the winter solstice has changed to a long day. We should sum up our experience and build canals to seize fertilizer sources. Hunan: The winter solstice arrives after the heavy snowfall. Select seeds to accumulate fertilizer for reproduction. Fujian: The winter solstice comes with heavy snow in December. Wheat is competing for tillers and vegetables are competing for sprouts. Plan to protect livestock and store materials for the winter, and prepare fertilizer and sideline business early.

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