Core Viewpoint - The "Nine Nines" tradition, starting from the winter solstice, reflects ancient wisdom regarding seasonal changes and weather patterns in China, marking the coldest period of winter and the transition towards spring [1][2][4]. Group 1: Significance of "Nine Nines" - The "Nine Nines" custom begins from the winter solstice, which is the shortest day of the year, leading to a gradual increase in cold as heat loss exceeds heat gain [2][4]. - The coldest periods in China typically occur during "Three Nines" and "Four Nines," with average temperatures reaching as low as -5.15°C during "Three Nines" [2][4]. Group 2: Regional Variations - In northern China, "Three Nines" is generally the coldest period, while in southern regions like Jiangnan and most of South China, "Four Nines" tends to be the coldest [5]. - The actual temperature variations can be influenced by climate change, El Niño, and cold air processes, leading to fluctuations from historical averages [5]. Group 3: Current Weather Patterns - This year, during "Three Nines," many regions experienced a temperature rise due to weak cold air, but "Four Nines" is expected to bring a significant drop in temperatures, potentially making it the coldest nine days of the winter [6][8]. - For instance, in Nanjing, temperatures are projected to drop from a high of 22°C to below freezing, illustrating the stark contrast in weather [6]. Group 4: Cultural Aspects - The "Nine Nines" tradition includes various folk songs that describe the weather changes and agricultural practices, reflecting local climate variations [9][10]. - The "Nine Nines" songs have evolved over time, with different regions having their unique versions that capture the essence of local weather patterns and farming cycles [9][10]. Group 5: Historical Context - The "Nine Nines" custom has been documented for over 1,400 years, with practices like "drawing nine" and "writing nine" serving as both a scientific record of weather changes and a cultural activity to welcome spring [13][15]. - These activities not only record weather but also express the anticipation of spring, embodying the philosophy of waiting for the seasonal transition [15].