White Dew, the 15th of the 24 solar terms in the lunar calendar, occurs when the Sun reaches the celestial longitude of 165 degrees. It is a solar term that reflects changes in temperature in nature. Dew is a unique natural phenomenon after the White Dew solar term. At this time, the weather is just as described in the Book of Rites: "The cool wind arrives, the White Dew falls, and the autumn cicadas chirp." According to Collected Explanations of the Seventy-Two Pentads in the Monthly Order, an annotation on White Dew states: "Moisture in soil and water condenses into dew. Autumn belongs to the element of Metal, and Metal is associated with the color white; white is the color of dew, and the air begins to turn cold." The ancient text Xiaowei Jing also notes: "Fifteen days after the End of Heat comes White Dew; Yin energy gradually grows stronger, and dew condenses into a white appearance."
In meteorological terms, by this solar term, the weather gradually cools down. During the day, the sunlight is still warm, but once the Sun sets, the temperature drops rapidly. At night, water vapor in the air condenses into tiny water droplets upon contact with cold surfaces. These droplets attach densely to the green stems, leaves, or petals of flowers and plants, appearing white. Especially when illuminated by the morning sun, they look even more crystal-clear and flawless, hence the name "White Dew."
By this solar term, it is mid-autumn, and the climate is similar to that of spring. Not only are flowers and trees still lush, but some flowers are even more vibrant than in spring—such as cotton roses, begonias, four-o'clock flowers, cockscombs, tall amaranths, and especially the reed flowers waving in the wind in the fields. An ancient poem describes this scene: "The sun shines on the bamboo by the window; dew wets the Chinese rose in the backyard. Night crickets chirp along the steps; fireflies flit around the bamboo." At this time, the sky is high and the clouds are light, with refreshing air and cool winds—truly the most pleasant time of the year. However, many living things on Earth will decline from prosperity amid the rustling autumn wind. Yet, the rise and fall of all things are part of nature; the laws of heaven are constant, not persisting for Yao nor perishing for Shun (legendary virtuous emperors of ancient China).
As the saying goes: "On the nights of White Dew and Autumn Equinox, the temperature drops colder each night." By this time, the summer monsoon is gradually replaced by the winter monsoon, with more northerly winds blowing. Cold air masses move southward more frequently. Additionally, as the Sun's direct rays shift southward, the Northern Hemisphere experiences shorter daylight hours and weaker sunlight intensity. Nights are often clear with few clouds, so the ground radiates heat quickly, leading to an accelerated drop in temperature.
"There is a saying: 'In the eighth lunar month, the Yanmen Pass opens, and frost follows in the geese's wake.' The eighth lunar month coincides with the White Dew solar term (usually September in the Gregorian calendar). At this time, migratory birds most sensitive to climate—such as yellow-billed grosbeaks, starlings, willow warblers, white-eyes, snipes, lapwings, and especially wild geese—send out signals for collective migration, preparing to fly south. They often set off on clear, moonlit nights in mid-autumn, as if delivering a message: the weather is turning cold, so hurry to harvest the crops and prepare warm clothes for the busy 'Three Autumns' (the period of autumn harvest, autumn plowing, and autumn sowing)."
In agriculture, after a year of hard work in spring and summer, people usher in the harvest season when fruits are fragrant and crops mature. The vast Northeast China Plain begins to harvest soybeans, millet, rice, and sorghum; late-autumn crops such as corn and sweet potatoes in the Northwest and North China are ripening; and cotton-producing areas enter the stage of full-scale, phased picking. Looking out over the fields, one sees sorghum glowing like fire, cotton spreading like clouds, soybeans splitting open their pods, and buckwheat bending under its own weight. Agricultural proverbs such as "At White Dew, sorghum is harvested; at Autumn Equinox, soybeans" and "Around White Dew, half of the naked oats and buckwheat are harvested" vividly depict this scene. Starting from White Dew, winter wheat sowing begins in the Northwest and Northeast China, and will soon start in North China.
Translator: KAN Bowen
Reviewer: ZHANG Yifan
