北方多地组织人工增雨作业缓解旱情，共增加降水约5亿吨

Core Insights - The northern regions of China experienced severe meteorological droughts in May, prompting extensive artificial rainfall operations to alleviate the situation [1][2] - The artificial rainfall efforts covered an estimated area of 683,000 square kilometers and resulted in an additional precipitation of approximately 500 million tons [2] Group 1: Artificial Rainfall Operations - Various meteorological departments across provinces such as Qinghai, Gansu, Shaanxi, Ningxia, Shanxi, and Inner Mongolia coordinated multiple artificial rainfall operations to combat drought [1][2] - Gansu Province conducted both aerial and ground-based artificial rainfall operations, with 2 aerial missions and 416 ground operations reported, resulting in precipitation across 1,129 towns and 2,218 observation stations [1] - In Shaanxi, 1 aerial operation and 182 ground operations were organized across multiple cities, while Ningxia executed 80 ground operations and 3 aerial missions, leading to significant improvements in soil moisture [2] Group 2: Technology and Methodology - Artificial rainfall is achieved by dispersing catalysts such as salt powder, dry ice, or silver iodide into clouds, which aids in the condensation of water vapor and the growth of raindrops [3] - The effectiveness of artificial rainfall is contingent upon the natural cloud conditions being suitable for such operations, emphasizing the importance of meteorological assessments [3]