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White Dew

Wild geese come, swallows depart

Introduction

Dew turns white, autumn deepens and birds fly south

White Dew is the fifteenth solar term, beginning when the sun reaches 165° of ecliptic longitude, around 7–9 September. Cold air becomes more active, nights cool, and moisture condenses as dew on plants. Its three pentads are wild geese arriving, swallows returning south, and birds storing food for winter. The northeast harvests millet, sorghum and soybeans, north China harvests and prepares to sow wheat, and the south guards against rice blast after autumn rain. Customs include collecting dew and drinking White Dew tea, and Taihu fishermen honour Yu the Great.

Timeline

Western Han to present
139 BCE · OriginThe Western Han Huainanzi (Tianwen xun, c. 139 BCE) sets out the twenty-four terms by the pointing of the Dipper's handle, recording 'fifteen days on, it points to geng: white dew descends', the earliest systematic attestation of White Dew.104 BCE · EvolutionWith the Taichu calendar of 104 BCE under Emperor Wu of Han, the twenty-four solar terms entered the official calendar, and White Dew became a fixed term in it.1645 · EvolutionIn 1645 the Qing Shixian calendar replaced equal time division with the true-longitude rule, fixing White Dew at the moment the sun reaches 165° of ecliptic longitude, as it still is today.
  1. 139 BCEOriginThe Western Han Huainanzi (Tianwen xun, c. 139 BCE) sets out the twenty-four terms by the pointing of the Dipper's handle, recording 'fifteen days on, it points to geng: white dew descends', the earliest systematic attestation of White Dew.
  2. 104 BCEEvolutionWith the Taichu calendar of 104 BCE under Emperor Wu of Han, the twenty-four solar terms entered the official calendar, and White Dew became a fixed term in it.
  3. 1645EvolutionIn 1645 the Qing Shixian calendar replaced equal time division with the true-longitude rule, fixing White Dew at the moment the sun reaches 165° of ecliptic longitude, as it still is today.

Heritage Listings

  1. 2006National List of Representative Items of Intangible Cultural Heritage1st batch · X-68 Twenty-Four Solar Terms of the Lunar Calendar · nominated by the China Agricultural Museum · collective item
  2. 2016UNESCO Representative List of the Intangible Cultural Heritage of HumanityThe Twenty-Four Solar Terms · knowledge in China of time and practices developed through observation of the sun's annual motion · collective inscription