Who is colder, slight cold or severe cold?

Both slight cold and severe cold belong to winter solar terms, in which slight cold is the fifth solar term and severe cold is the sixth solar term. Slight cold and severe cold are both solar terms indicating weather changes. The slight cold solar term is characterized by cold, but it is not extremely cold, so it may be even colder later.

According to the meteorological records for many years, slight cold is basically the time when the temperature is relatively low in a year. As long as the temperature of great cold is less than slight cold, most of them are slightly colder than great cold. After the slight cold, the temperature will gradually increase, so the average temperature of the great cold is slightly higher than that of the slight cold.

According to the meteorological data for many years, the slight cold is basically the lowest temperature day in a year, and only a few years have the great cold temperature lower than the slight cold; As soon as the winter solstice arrives, it enters the "Sanjiu", in which "Sanjiu" is the coldest time and always falls within the slight cold solar terms; There is also a folk saying that "a slight cold is better than a severe cold". Why on earth is this?

It turns out that in the last solar term-winter solstice, although the solar heat obtained on the ground was very small, some heat in the deep soil could still be emitted upwards, so it was not the coldest time of the year. In the slight cold, the heat in the deep soil is lost to the lowest point. Although the days are slightly longer and the sun's light and heat are slightly increased, in fact, this is the period when the heat is the most "unable to make ends meet", so it becomes the coldest season all year round.

Since the slight cold is colder, why did the ancients increase the cold after the slight cold, instead of arranging it backwards? This is because the traditional culture of China pays special attention to "extremes meet" and thinks that the "heaven" of alternating cold and summer is to recover quickly after catching a cold. If you get a bad cold before the slight cold, you can't feel "recovered" after the coldest, so it is in line with the thinking habit of China people to put the bad cold behind you and return to beginning of spring quickly after the bad cold.