Is it cold in the south?

Lead: Every year, during the big and small cold periods, people in the north and south of China begin to argue whether it is cold in the south or cold in the north. Northerners think it is colder in mild cold season, while southerners think it is colder in severe cold season. So, which do you think is colder, the severe cold or the slight cold in the south? Is it a slight cold or a severe cold in the south? Let's get to know each other.

Which is colder, the severe cold or the slight cold in the south of China?

According to China's long-term meteorological records, there is no slight cold in the great cold solar terms in the northern region; But for most parts of the south, the coldest is the great cold solar term. Great cold, like slight cold, is also a solar term indicating the cold weather. Great cold refers to extremely cold weather.

Slight cold and severe cold are the coldest seasons of the year;

Slight cold and severe cold coincided with 3949, which was the coldest period.

In winter, the so-called "cold on March 9 and April 9" is usually not too cold before the winter solstice, but the real cold is after the winter solstice, especially on March 9 and April 9.

During the winter solstice, the daytime is the shortest, the angle of direct sunlight on the ground is the smallest, and the sunshine intensity per unit area on the ground is also the smallest, so the ground gets the least solar heat every day, and the daily heat budget deficit on the ground has not reached the maximum. On the solstice after winter, although the day is growing day by day, the growth rate is very slow. From the winter solstice to the "March 9" period, the average daily growth is only about one minute. At the same time, the angle between the direct angle of the sun and the ground is slowly increasing. The daily heat budget of the ground is still in deficit, so it continues to lose heat and the ground temperature continues to drop. The deficit of total heat balance on the ground only reached the maximum during "March 9 and April 9". Because the air temperature is mainly affected by the ground temperature, this leads to the lowest temperature during "March 9 and April 9". In addition, around March 9, the cold air mass in Siberia also developed to a very strong stage, and the frequent invasion of strong cold air is also one of the reasons for the low temperature.

The earth absorbs heat from solar radiation during the day and releases heat at night. In summer, you absorb more heat during the day and emit less heat at night, so you can accumulate some heat every day. In winter, less heat is absorbed during the day and more heat is released at night. Not only can you not accumulate it every day, but you also need to use some of the heat accumulated in summer. During the winter solstice, less heat is absorbed during the day, but there is still some stored heat on the earth. After the winter solstice, less and less heat is stored. On March 9 and April 9, the earth's heat storage is the least in a year, so it is the coldest.

Is it cold on March 9th or April 9th?

Generally, people think that it is coldest in three or nine days, but there is actually a saying that it is colder in four or nine days than in three or nine days. Now let's take a look at these two statements separately.

Sanjiu is colder.

During the winter solstice, the daytime is the shortest, the angle of direct sunlight on the ground is the smallest, and the sunshine intensity per unit area on the ground is also the smallest, so the ground gets the least solar heat every day, and the daily heat budget deficit on the ground has not reached the maximum.

On the solstice after winter, although the day is growing day by day, the growth rate is very slow. From the winter solstice to the "March 9" period, the average daily growth is only about one minute. At the same time, the angle between the direct angle of the sun and the ground is slowly increasing. The daily heat budget of the ground is still in deficit, so it continues to lose heat and the ground temperature continues to drop.

The deficit of total heat balance on the ground only reaches the maximum in the season of March 9. Because the temperature is mainly affected by the ground temperature, this leads to the lowest temperature in the "March 9" season. In addition, around March 9, the cold air mass in Siberia also developed to a very strong stage, and the frequent invasion of strong cold air is also one of the reasons for the low temperature.

Forty-nine is colder.

There is a folk proverb in China that "the first nine days are warm, and the last nine days are cold". It turns out that if the first nine days are warm, the next winter will be particularly cold. Therefore, it is said that "the first day is not greedy, and the rain and snow continue to winter." "Yanjing Age" said: "The winter solstice on March 9 is difficult." It means that it has entered the coldest stage in cold weather since March 9. "Jing Fang Yizhan" said: "The solstice after beginning of winter is extremely cold on the 30th", "The third solstice after beginning of winter is the coldest in the twelfth month."

Later, people generally thought that March 9 was the coldest day, but in fact, April 9 was the coldest time in winter. It was only a few days before March 9 that the temperature changed greatly, and suddenly it became cold, so the body did not adapt, so it was particularly cold. On April 9, although the temperature was lower than that on March 9, the temperature difference changed little, and it didn't feel as cold as when it entered March 9 from February 9.