The arrival of the cold dew solar term means that autumn has arrived.

cold dew literally means "cold" and "dew" means the phenomenon that water vapor in the near-surface layer condenses into dew. From the meteorological point of view, the cold dew solar terms, like the two solar terms of Bailu and first frost, show more obvious significance of heat change than its moisture change, which more embodies a process of temperature change and seasonal change. During the cold dew season, Nanling and its north area have entered autumn, while the northeast and northwest areas are about to enter winter.

Although it is only a short period of 15 days from the cold dew to the solar term first frost behind it, it is a period of time in a year when the temperature drops rapidly. It is common for the average daily temperature to drop by 8℃ and 1℃ after a cold air. Therefore, this season is a turning point of climate change in many parts of China.

historical origin

cold dew is the end of the full moon in the dry calendar and the beginning of the full moon. At night, looking up at the starry sky, you will find that the "Big Mars" (Antares) representing midsummer has sunk in the west. After the cold dew, the height of the sun continued to decrease and the temperature gradually decreased. Cold dew is called "cold dew" because the temperature drops a lot compared with the solar term of Bailu, and cold produces dew condensation. "twenty-four solar term" said: "In September, the dew is cold and will condense." At this time, the temperature is lower than when it is "white dew", with more dew and a chill day and night.

among the people in China, there is a proverb that "the dew turns white first and then cold", which means that after the solar term of the dew, the dew turns from a little cool in early autumn to a little cold in late autumn.

There is also a proverb about cold dew: "Cold dew has crossed three dynasties, and you have to find a bridge when crossing the water", which means that the weather is already chilly, and you can't wade across the river or go to the fields barefoot as before. During the cold dew, people can obviously feel the change of temperature difference. From white and crystal dew to cold and freezing, it vividly reflects the continuous decline of temperature. As the cold grows, everything is gradually bleak.