Indian scientists plan to add substances to clouds above the capital New Delhi in an effort to produce rain to reduce pollution. 

印度科学家计划在首都新德里上空的云层中添加物质，以产生降雨来减少污染。

The method to artificially produce rain is called cloud seeding. The process involves adding different chemicals to clouds to cause rain. When rain falls from the sky, water droplets can attach to pollution particles and bring them down to the ground. 

人工降雨的方法称为人工降雨。 该过程涉及向云中添加不同的化学物质以引起降雨。 当雨从天而降时，水滴会附着在污染颗粒上并将其带到地面。 

New Delhi has been rated the city with the most air pollution in the world. Reports say the problem has worsened across the city in recent weeks. 

新德里被评为世界上空气污染最严重的城市。 报道称，最近几周全市的问题变得更加严重。 

Air quality decreases in the city ahead of winter each year. During this time, cold air can trap many pollutants, including gases from vehicles, industry, building projects and agricultural burning. 

每年冬季到来之前，城市的空气质量都会下降。 在此期间，冷空气可以捕获许多污染物，包括来自车辆、工业、建筑项目和农业燃烧的气体。 

Scientists expect some clouds over the city around November 20. They hope the clouds will result in heavy rainfall – when sprayed with a salt mixture. 

科学家预计 11 月 20 日左右，该市上空将出现云层。他们希望这些云层在喷洒盐混合物后会带来强降雨。 

The project is being led by Manindra Agrawal, a scientist at the Indian Institute of Technology in the central city of Kanpur. He told Reuters news agency the salt mixture will include silver iodine to help produce rain. It is to be sprayed on clouds over a 100 square kilometer area. Agrawal said the project will cost about $120,000. 

该项目由中部城市坎普尔印度理工学院的科学家曼宁德拉·阿格拉瓦尔 (Manindra Agrawal) 领导。 他告诉路透社，盐混合物中将含有碘银，以帮助产生降雨。 它将被喷洒在100平方公里的云层上。 阿格拉瓦尔表示，该项目将耗资约 12 万美元。

The local government in New Delhi, a city of 20 million people, has already closed schools, stopped building activities, and said it will place restrictions on vehicle use to control pollution. 

拥有 2000 万人口的新德里当地政府已经关闭了学校，停止了建筑活动，并表示将限制车辆使用以控制污染。 

The air quality index in the city was 506 on November 9. This level is considered "hazardous" by IQAir, a Swiss company that describes itself as an “air quality solutions” business. 

11月9日，该市的空气质量指数为506。这个水平被自称为“空气质量解决方案”企业的瑞士公司IQAir认为是“危险”水平。 

Gufran Beig is head of the Indian government's air-quality measuring agency SAFAR. He told Reuters the city needs heavy and widespread rain to wash away the pollutants. Beig added that light rain could worsen the situation. 

Gufran Beig 是印度政府空气质量测量机构 SAFAR 的负责人。 他告诉路透社，该市需要大范围的大雨来冲走污染物。 贝格补充说，小雨可能会使情况变得更糟。

The SAFAR head said current airflow is carrying smoke from crop burning in the states of Punjab and Haryana to Delhi. This smoke adds to the city’s existing pollution sources. "So, unless a huge pressure is established by intense rain, this chain of transport from Punjab to Delhi will not be broken,” Beig said. 

萨武装部队负责人表示，目前的气流正将旁遮普邦和哈里亚纳邦燃烧农作物产生的烟雾带到德里。 这种烟雾增加了城市现有的污染源。 贝格说：“因此，除非强降雨造成巨大压力，否则从旁遮普邦到德里的这条运输链不会被破坏。” 

About 38 percent of pollution in the capital has been caused by stubble burning in Punjab and Haryana, a recent government statement said. Farmers carry out stubble burning to clear material left behind from rice harvests so they can plant other crops. Indian officials directed leaders in both states to "take effective actions" to identify and limit stubble burning, the statement added. 

最近的一份政府声明称，首都约 38% 的污染是由旁遮普邦和哈里亚纳邦焚烧秸秆造成的。 农民通过焚烧秸秆来清除水稻收割后留下的物质，以便种植其他作物。 声明补充说，印度官员指示两个邦的领导人“采取有效行动”来识别和限制秸秆焚烧。

Officials in New Delhi are seeking approval for the project from the Supreme Court, Reuters reported. 

据路透社报道，新德里官员正在寻求最高法院批准该项目。 

Several countries have used cloud seeding in an effort to produce rain, improve air quality and water crops in times of extreme dryness. These include Mexico, the United States, China, Indonesia and Malaysia. 

一些国家已经使用云播技术来产生降雨，改善空气质量，并在极端干旱时期给作物浇水。 其中包括墨西哥、美国、中国、印度尼西亚和马来西亚。