“三伏天”为何是一年最热的时候？（把自然讲给你听）

Group 1 - The article discusses the phenomenon of "Sanfu days" being the hottest period of the year, with significant temperature increases due to the imbalance between heat absorption and heat dissipation on the ground [1][2] - It highlights the trend of earlier high temperatures in China, with the first high-temperature day occurring earlier in most regions from 1991 to 2020 compared to 1961 to 1990 [2] - The article notes that the number of high-temperature days has generally increased over the past 60 years, with an average increase of 6.7 days every decade in annual warm days [2] Group 2 - The extreme high temperatures are linked to the Western Pacific subtropical high-pressure system, which has been controlling the weather in the central and eastern regions of China [2] - The article emphasizes the health risks associated with extreme heat, urging the public to take precautions and limit outdoor activities during high-temperature periods [2]