原标题：唠"科"话丨这轮广东的雨为啥这么大？ 新华社广州8月7日电（记者田宇、胡拿云）这几天，广东出现大范围强降雨过程，让人感觉"雨下 个没完"。广东省防汛防旱防风总指挥部从3日至5日连续将防汛应急响应从Ⅳ级调整至Ⅱ级。国家防减 救灾委6日对广东启动国家四级救灾应急响应。在广州、肇庆、清远等地，出现内涝、树木倾倒、甚至 发生山洪、道路塌陷。广东这轮降雨为何下得如此猛烈？它又将持续到何时？ 这轮降雨强度为何这么大？ 要解析这轮强降雨的成因，不妨先从降雨的基本原理说起。简单来讲，形成降雨需要三个核心条 件：一是"动力抬升机制"，二是"充足的水汽"，三是"较多的凝结核"——空气中悬浮的尘埃、烟尘等微 粒，能让水汽更易附着、聚集，进而形成云层。具体可以这样理解：当含有大量水汽的湿润空气快速上 升时，由于高空温度较低，水汽会因降温而凝结成雨滴，最终落到地面形成降雨。 要解开广东本轮强降雨的成因，不妨聚焦几个关键的气象"推手"： 首先是抬升机制源于低涡。它和台风很像，甚至可以形容为"在陆地上的台风"。低涡生成于陆地， 一般覆盖范围在200公里至2000公里以内，而台风生成于海上，通常覆盖范围在2000公里以上。在北半 球 ...

Group 1 - The core viewpoint of the article highlights the severe impact of the recent heavy rainfall in Beijing, which peaked on July 28, 2025, leading to significant flooding and the displacement of over 80,000 residents [1][2][3] - The rainfall lasted for 147 hours, with an average precipitation of 210.4 mm across the city, and the maximum recorded in the Miyun District reached 573.5 mm, which is significantly higher than the average annual rainfall for that area [2][3] - The heavy rainfall has been attributed to the geographical features of Beijing, particularly the mountainous regions that occupy about 62% of the city's area, which create conditions for intense rainfall through orographic lift [13][15] Group 2 - The Miyun Reservoir, a critical water source for Beijing, has been releasing water to manage the flood situation, with a total discharge of 1.2 billion cubic meters, equivalent to the volume of 8.5 West Lakes [3][11] - The article emphasizes the importance of Miyun District, which serves as a key geographical and hydrological point for the city, with historical significance reflected in its long-standing infrastructure, including the Great Wall [4][11] - The interaction between the mountainous terrain and water systems is crucial for understanding the historical and current hydrological dynamics of Beijing, as many rivers originate from the surrounding mountains [21][22]

Core Viewpoint - The article discusses the severe flooding in Beijing due to extreme rainfall, highlighting the impact on infrastructure, emergency responses, and the ongoing weather conditions. Group 1: Rainfall and Weather Conditions - Beijing experienced a total rainfall of 543.4 millimeters over four days, which is nearly equivalent to the city's average annual precipitation of about 600 millimeters [4] - The rainfall event lasted for 147 hours, starting from July 23, with the heaviest downpours occurring in the northern and western parts of the city [5][6] - The phenomenon known as "train effect" caused prolonged heavy rainfall in certain areas, leading to significant accumulations [6] Group 2: Emergency Response and Impact - As of July 28, 30 fatalities were reported due to the flooding, with the majority occurring in the Miyun district [4] - A total of 80,332 people have been evacuated from affected areas, with the highest numbers from Miyun, Huairou, and Fangshan districts [8] - The National Disaster Reduction and Relief Committee activated a level four emergency response, allocating 200 million yuan for recovery efforts in severely impacted areas [8][9] Group 3: Infrastructure Damage - The flooding caused damage to 31 roads, with 16 routes still not repaired, and 136 villages experienced power outages [8] - Communication infrastructure was also affected, with 62 optical cables damaged and 1,825 base stations out of service [8] Group 4: Water Management - The Miyun Reservoir, a crucial water source for Beijing, has seen a significant increase in inflow, with 7.3 billion cubic meters entering and 1.2 billion cubic meters released as of July 29 [11][10] - The reservoir's outflow rate was recorded at 1,120 cubic meters per second, impacting downstream river levels [11]

Core Viewpoint - The recent heavy rainfall in northern China, particularly in Beijing and Hebei, is attributed to abnormal atmospheric circulation patterns, with the subtropical high pressure system playing a significant role in the early onset of the rainy season [1][3]. Group 1: Weather Patterns and Impacts - The subtropical high pressure has shifted northward, leading to an influx of warm, moist air into northern China, which has resulted in extreme rainfall events [1][2]. - The average rainfall in the North China region has reached 121 mm, which is nearly 30% higher than the historical average for the same period [2]. - The rainy season in North China began on July 5, 13 days earlier than the historical average, marking the earliest start since 1961 [2][3]. Group 2: Typhoon Influence - Typhoon "Zhu Jie Cao" has been reclassified and is expected to impact eastern China significantly, with strong winds and heavy rainfall predicted in several regions [4]. - The typhoon indirectly affects the rainfall patterns in northern China by altering the atmospheric circulation, which influences the subtropical high pressure's position and intensity [4]. Group 3: Future Weather Forecast - A strong rainfall event is anticipated in northern China, with warnings issued for potential mountain floods and geological disasters due to cumulative rainfall effects [5]. - The overall precipitation trend is expected to weaken, but localized heavy rainfall may still occur [5].

Group 1 - The recent heavy rainfall in northern China has been influenced by a combination of factors, including stable subtropical high pressure, prolonged convective activity, and orographic lifting from the Yanshan and Taihang mountains [2][4] - Specific areas such as Yixian in Hebei and Miyun in Beijing have experienced localized rainfall exceeding 400 to 500 millimeters, approaching their annual average precipitation [2] - The current heavy rainfall event is expected to gradually diminish by the 30th, as the subtropical high pressure retreats southward and moisture transport decreases [4] Group 2 - Typhoon "Zhu Jie Cao" is expected to impact the eastern China region, with forecasts indicating it may make landfall on the 30th, bringing significant rainfall to areas like southern Jiangsu, Shanghai, and eastern Zhejiang [5][7] - The typhoon's trajectory suggests it will slow down as it moves inland, necessitating close monitoring of its potential for sustained rainfall in the eastern regions [7] - The weather patterns indicate a shift from northern heavy rainfall to increased precipitation in the eastern coastal areas due to the typhoon's influence [5]

Core Viewpoint - Beijing has issued a red rainstorm warning, indicating severe weather conditions with expected rainfall exceeding 150mm in most areas and potentially reaching 300mm in some locations, posing high risks of natural disasters such as flash floods and landslides [1][2]. Group 1: Weather Conditions - The red rainstorm warning was upgraded from an orange warning within three hours, highlighting the intensity of the rainfall [1]. - Rainfall from July 24 to 25 reached an average of heavy rain levels, with significant short-term rainfall recorded in northern areas, including 95.3mm in one hour in Dongyu, Huairou, and a total of 315.3mm over six hours in Huangtuliang, Miyun [1]. - Continuous heavy rainfall was observed, with an average of 34.9mm recorded from 6 AM on July 27 to 6 AM on July 28, indicating persistent heavy rain conditions [1]. Group 2: Meteorological Analysis - The extreme rainfall in northern mountainous areas was attributed to the uplift effect of southwest warm moist air from the edge of a subtropical high, causing continuous rain band formation [2]. - The weather pattern is expected to change, with the influence of a high-altitude shortwave trough and the ongoing warm moist conditions, leading to significant rainfall and potential severe convective weather, including thunderstorms and hail [2]. - Rainfall is expected to continue into the night of July 28, with a shift to localized severe convective weather expected on the afternoon of July 29 [2]. Group 3: Public Advisory - Meteorological authorities advise the public to stay updated on weather forecasts and warnings due to the rapidly changing weather conditions and to take necessary precautions [3].