立冬是二十四节气的第十九个节气。立,表示自此开始,因此立冬意味着冬季正式来临。立冬与立春、立夏、立秋合称四立,在古代社会中是个重要的节日。今年的立冬始于11月7日。
在清代,立冬时节,秋粮入库,满族八旗和汉军八旗人家就要隆重举行烧香祭祖活动。汉八旗的祭祀称为“烧旗香跳虎神”,满八旗称“烧荤香”。
立冬是从秋到冬转换的标志,因此很受古人重视。皇帝会率领百官进行祭祀,百姓们则举行仪式祭祀地神,以示感谢,祈求来年的丰收。
 
立冬之后南北温差更加拉大。北方的许多地方已是风干物燥、万物凋零;而华南仍是青山绿水、鸟语花香。
古时中国是个农耕社会,百姓们一年四季都在忙碌操劳,到立冬就得好好休息一下,补偿平时精力的不足,顺便犒赏一年来辛苦的一家人。
立冬是秋季与冬季相交的日子,所谓“交子之时”。古人为了犒劳一年的辛勤农耕,再取“交子”谐音,常在立冬当日食用饺子,这个习俗也流传了下来。
The traditional Chinese lunar calendar divides the year into 24 solar terms. Start of winter, the 19th solar term of the year and the first solar term of winter, begins on Nov 7 this year.
Start of winter is a festive time for the people of Manchu Eight Banners and Han Eight Banners in Benxi, Liaoning province. The Eight Banners (baqi) were military and administrative divisions during the Qing Dynasty (1644-1911).
Four beginnings of seasons were important festivals in ancient times. The emperor ate only vegetables prior to the solar term and led his officials to the suburbs on the day of start of winter to partake in a ceremony to "welcome the winter". 
Temperatures across China differ greatly after start of winter. North China may experience a much drier and cooler climate, while those living in the south can still enjoy green mountains and fragrant flowers.
Ancient China was an agricultural society, and most crops were harvested by start of winter. As a reward, farmers often ate high-calorie meals (such as mutton and pork) to reward a year's hard work and to nourish and prepare the body for the harsh winter weather.
Start of winter sits at a cross point between autumn and winter, or at the time of jiaozi. People in ancient China took the homophone and ate dumplings, also jiaozi in Chinese, on the day of start of winter, and the custom was passed on to today. 
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