Millennium means that the weather turns cold and cold produces dew condensation. Millennium is the 15 solar term in the "twenty-four solar terms", and the third solar term in autumn is the end of the application of the moon in the lunar calendar and the beginning of the unitary month. Fight with your fingers. The sun reaches 165 degrees. Gregorian calendar September 7-9.

Millennium is an important solar term, reflecting the cold growth of nature. As the cold air turns to attack, it is sunny and hot during the day, but the temperature drops rapidly after the evening, and the temperature difference between day and night gradually widens.

Phenological phenomena:

During the Millennium solar term, the summer heat gradually disappears, the autumn air is crisp, the osmanthus fragrance is fragrant, migratory birds such as Hongyan and Swallow begin to fly south to avoid the cold, and various birds begin to store food for the winter.

"Hongyan comes, Xuanniao returns." After the Millennium, migratory birds that are most sensitive to climate migrate collectively. Hongyan began to fly from the north to the south, and mysterious birds from the south also flew back to the north, and various birds began to store food for winter.

There is a saying in the folk proverb: "The white dew flies in the south in the autumn night", "When beginning of autumn knows it, it makes people sleep, and the sunflower laughs in summer, and the white dew returns to the wild goose, and the osmanthus fragrance fills the garden in the autumn equinox". Therefore, migratory birds like geese are regarded as a symbol of autumn.