Lidong, the Start of Winter, is the nineteenth solar term, at the sun's longitude of 225 degrees, around the seventh of November. It is a sectional (jie) term and marks the astronomical beginning of winter. The harvest is stored, the fields lie fallow, and the year turns inward toward rest. In the farming almanac it signals the season of conservation, and its customs centre on nourishment against the cold, in the north the eating of dumplings, and more widely the winter practice of building up the body with warming, tonic foods. Being a solar marker, it falls near the same Gregorian date each year. These are the observances of the East Asian agricultural tradition, resting on the twenty-four-fold division of the tropical year into equal solar arcs anchored to the sun's position.
Lidong, the Start of Winter, falls at 225 degrees, around 7 or 8 November, and is a jie, or sectional, term, opening the fourth and last of the traditional calendar's four seasons. As with the start of the other three seasons, Lidong's astronomical date does not correspond to when winter conditions actually arrive across China's varied climate. The term carries one of the solar calendar's more widely kept folk customs: in northern China it is traditionally marked by eating jiaozi, dumplings, said in one popular explanation to be shaped like ancient Chinese ingots or to resemble ears, tied to a folk story about the physician Zhang Zhongjing distributing warming dumpling-like medicine to treat frostbitten ears among the poor.