让人七上八下的“七下八上”到底有多猛？

Core Viewpoint - The article discusses the onset of the "Seven Down, Eight Up" flood prevention period in Northern China, highlighting the significant rainfall and extreme weather events expected during this time [1][4][11]. Summary by Sections Rainfall Patterns - The "Seven Down, Eight Up" period typically occurs from late July to early August, during which Northern China experiences concentrated rainfall, accounting for about one-third of the annual precipitation [4][10]. - Historical data from 1991 to 2020 indicates that major cities in the region, such as Beijing, Shijiazhuang, and Jinan, receive over 50% of their annual rainfall during these two months [4][6]. Extreme Weather Events - The article references several historical extreme rainfall events, including the 2021 Zhengzhou and 2012 Beijing floods, emphasizing the potential for record-breaking rainfall during this period [6][10]. Meteorological Influences - The article identifies key meteorological factors contributing to the rainfall, including the influence of the subtropical high-pressure system, warm moist air from the sea, and cold air from Siberia, which interact to create severe weather conditions [7][10]. - The geographical features, such as the Taihang and Yanshan mountain ranges, play a significant role in enhancing rainfall as warm moist air is forced to rise and cool, leading to precipitation [10]. Forecast for Current Year - According to the National Climate Center, the forecast for this year's "Seven Down, Eight Up" period indicates above-normal precipitation in regions such as Inner Mongolia, Heilongjiang, and Shandong, with rainfall expected to be 20% to 50% higher than usual [10][11].