“数九”，因何从冬至开始？

Group 1 - The concept of "Shu Jiu" (Counting the Nines) begins on the Winter Solstice, marking the start of a period that lasts for 81 days, culminating in the arrival of spring [2] - The "Shu Jiu" method is particularly relevant to northern China, especially the Yellow River's middle and lower reaches, as it symbolizes the transition from winter to spring [2] - The 2026 Spring Festival falls on February 17, which is relatively late compared to previous years, due to the occurrence of a leap month in 2025 [2] Group 2 - The "Shu Jiu" folk song describes seasonal changes and agricultural life, reflecting the cultural significance of this period [5] - The phenomenon of "river opening" typically occurs when temperatures stabilize above 0 degrees Celsius, which may align with the timing of the Spring Festival in 2026 [5] - Traditional practices emphasize the importance of warmth and appropriate clothing during the cold winter months, highlighting health considerations during this season [5]