White dew is the 15th solar term in the 24 solar terms and the third solar term in autumn. To the white dew, the summer heat is basically over, and the cold is gradually emerging. The summer wind and the winter wind alternate, the cold air gradually attacks the south, the direct sun point moves south, the northern hemisphere sunshine time becomes shorter, the light intensity weakens, the weather is clear, the ground radiation heat dissipation is fast, so after the white dew, the temperature drops faster, about these little knowledge of the white dew festival, how much do you know?
First, the explanation of the name of white dew
There are two main explanations for the name of White dew, one is related to phenology, and the other is related to the traditional Chinese five-element theory.
● About Phenology:
After the white dew, it is “the autumn wind is bleak and the weather is cool, and the grass and trees shake down the dew for frost.” (Cao PI (Wei) “Yan Song Song Two · One”) season, the cold gradually, dew condensation, in the morning will see Yingying dew under the sunrise white shimmer, showing a white on the grass and trees.
● Five elements theory:
In ancient China, four times corresponded to five elements, the four seasons were spring wood, summer fire, autumn gold and winter water, and the soil was located in the center of the four seasons. Wu Cheng, a Yuan scholar, described the white dew in this way in the Collection of the seventy-second Hou of the Lunar Season:
“Water and water moisture condensation for dew, autumn is gold, golden white, white dew color, and qi beginning cold also.”
It means that water vapor condenses into dew at night, autumn corresponds to the five elements of gold, gold is white, white is also the color of autumn dew, cold begins to grow, the weather gradually turns cool, so the name “white dew”.