Cold knowledge: who is colder, slight cold or severe cold?

As the name implies, the ancients have divided it into sizes according to their names, with great cold being the coldest and slight cold second. However, according to China's long-term meteorological statistics, the annual minimum temperature in most parts of the south appears in the severe cold solar terms, but not in the north. In northern China, there is even a saying that "slight cold is better than severe cold, which is common but not rare". So in the north, slight cold is actually colder than great cold.

Since slight cold is colder than severe cold, why is it called slight cold?

First, the ancients described the degree of cold, because there was no accurate way to quantify the temperature, so they had to find another way. Look around to see if the ice is thicker and harder. As the saying goes, "ice is abundant, but Shui Ze's belly is firm". Freezing for three feet was not built in a day. "Ground freezing" needs a gradual process from top to bottom, which is much slower than the temperature drop.

We measure the cold according to the temperature, and it is coldest when it is slightly cold, so it is the coldest. The ancients measured the cold according to the thickness of the ice layer, and the ground was the strongest during the great cold, so it was said that the great cold was the coldest.

Second, the ancients' definition of the degree of cold was also based on people's subjective feelings. During the slight cold, although the weather is very cold, people's tolerance is acceptable and they will not feel particularly cold. When it comes to the great cold, even if the temperature doesn't get lower, people have been tortured by the cold, and may feel that the great cold is even colder. Therefore, in the eyes of the ancients, the cold of the great cold pays more attention to the cumulative effect.

Third, the ancients believed in the concept of "extremes meet", as long as summer begins to turn cold, it is autumn; As long as winter begins to pick up, it is spring. In two extreme seasons, the peak is always at the end. Summer is from slight heat to great heat and winter is from slight cold to severe cold. Therefore, the last solar term in winter won the name of great cold, and the coldest solar term can only be deigned to be called slight cold.

Therefore, it is not necessarily the fallacy of the ancients to judge who is colder by slight cold and severe cold, mainly because of the different perspectives of measuring cold in ancient and modern times.

In addition, there may be another reason, that is, in the pre-Qin period when the 24 solar terms began to sprout and were founded, the great cold in the Central Plains may indeed be colder than the slight cold. Of course, this is just a guess that lacks historical data and is justified by the ancients.