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Along-awaited rain on the morning of August 10 left drought-stricken residents in Linquan County, east China’s Anhui Province, exalted. Farmers flocked to corn fields to check crops and spread fertilizer.
Since late July, Anhui had been parched by drought and temperatures above 35 degrees Celsius. Tens of thousands of people faced shortages of drinking water and large areas of crops were damaged.
It was much needed, for the cost of pumping ground water to irrigate the fields was high.
Yet farmers might not be aware that this 22-52 mm downpour was the result of a weather modification operation carried out by the Fuyang Meteorological Bureau, which had launched cloud seeding rockets to induce precipitation.
Prevalent practice
Weather modification is a frequent practice in China. The number of weather modification operations carried out in the country is the highest in the world, according to the China Meteorological Administration (CMA).
Zheng Guoguang, head of the CMA, said in May that artificial rain enhancement operations had covered more than half of the country’s territory.
Data released by the CMA show that China has carried out nearly 559,000 weather modification operations since 2002, launching more than 900,000 rockets and 8.85 million shells. The effort created an estimated 489.7 billion tons of rainfall.
The country’s weather modification system employs 47,700 people, and has an arsenal including more than 7,034 rocket launchers, more than 50 planes and nearly 6,902 guns.
On August 30, the Chinese Government published a plan, outlining that the country’s aims to build a relatively complete weather modification system by 2020.
The document says that by 2020, China plans to increase precipitation by 60 billion tons annually via cloud seeding, as well as extend the coverage of artificial hail suppression to more than 540,000 square km from the current 470,000 square km, a near 15-percent increase.
“Weather has been modified to relieve drought, prevent forest fire, protect ecological environment, fill reservoirs, ensure good weather for major events, cool down cities and improve urban environment,” said Wang Guanghe, Deputy Director of the Artificial Weather Intervention Center under the CMA.
Commonplace weather modification operations include rainfall adjustment by dispersing a catalyst to the clouds to delay or induce rain as well as measures to suppress hail, dissipate clouds, prevent frost and blunt lightning storms.
According to Yu Ziping, Deputy Chief Engineer of the China Enginery Research Institute, there are two cloud seeding processes: One is to use ice-forming substances such as silver iodide or dry ice to freeze supercooled water droplets in a cold cloud, and the other is to use water-attracting substances such as salt to cause droplets to condense within a warm cloud.
“Catalysts can be dispersed into cloud by planes, guns, rockets and in some circumstances, natural air currents,” Zheng said.
The potential for average artificial rainfall in China could reach up to 280 billion tons per year, which is seven times the storage capacity of the Three Gorges reservoir, the country’s largest.
The CMA said that in the next five years, it will increase the efficiency of artificial rain enhancement by 3 to 5 percent, and expand the operation area of hail suppression by 5 percent.
Past experience
“China generally is dry, so it explores all available measures to increase precipitation,”said Mao Jietai, a professor at the Department of Atmospheric and Oceanic Sciences of Peking University’s School of Physics.
Mao said that drought is a major meteorological disaster that threatens the country’s food and environmental security, and the percapita water availability in China is less than one fourth of the world average.
In addition, hail and heavy fog occur frequently. Official statistics estimate that abnormal meteorological phenomenon have incurred more than 70 percent of all losses caused by natural disasters.
As early as in the 17th century, Chinese people attempted to suppress hail by firing gunpowder from cannons into yellow clouds floating from mountains during the months of May and June, for such clouds were believed to carry hail, according to Yu.
The first successful cloud seeding operation in China took place in 1958 when a plane was used to spread dry ice into clouds to quench a severe drought in northeastern Jilin Province. Thereafter, weather modification technology has developed fast in the country.
During the 2008 Summer Olympic Games in Beijing, weather modification technology was used to deliver a rain-free opening ceremony on August 8.
Historical data indicated a 41-percent possibility of precipitation on that date in Beijing. To prevent rain from ruining the ceremony, the Beijing Meteorological Bureau set up 26 weather control stations in Beijing’s vicinity, hired 32,000 people, and deployed aircraft, rockets and artillery to spread silver iodide crystals and dry ice in clouds 50 km upwind of Beijing, according to the Xinhua News Agency.
Finally, rain-bearing clouds were eliminated before reaching the Bird’s Nest, the nickname for the roofless National Stadium, where the Olympic opening ceremony was staged.
Cloud seeding has also been used before major events to induce a cheerful mood among the population. Beijing was shrouded in cloud and smog in the three days before October 1, 2009, the 60th anniversary of the founding of the People’s Republic of China when a grand military review was scheduled. The weather was depressing. Artificial rain was made in Beijing and neighboring provinces, then on the anniversary day, the parade was held under an exceptionally clear sky.
“Since rain cannot be created from nowhere, accurate weather forecasts and understanding of the clouds’ conditions are required for successful weather modification. Meteorological equipment such as digital radar and microwave radiometer is needed,” Yu said.
China has made steady progress in weather modification technology in the past decades, yet it still lags behind leading countries in the field.
Yu said that so far, the country still imports a significant portion of equipment, and Chinese engineers would like to develop its own advanced equipment to reduce the technology gap between China and leading countries.
Environmental impacts
With the rising use of weather modifica- tion, people are concerned with whether the catalysts added to the clouds will do harm to the environment. Zheng said that the environmental impacts of weather modification are negligible, adding that some of the most common catalysts such as dry ice and liquid nitrogen are naturally present in the air and are not at all harmful.
“Even though silver iodide is used to seed cloud, every shell only contains 1 gram of the chemical, so less than 1 ton of silver iodide is used in a year over a total area of about 5 million square km,” Zheng said.
Artificial rain making has been carried out frequently near Miyun Reservoir, a major drinking water source in suburban Beijing. The office in charge of weather modification under the Beijing Metrological Bureau analyzed the silver iodide level in Beijing’s rainwater and found it too far below the national standard and the standard set by the World Health Organization.
As to whether such operations may impact the global climate, Wang said that the impacts of weather modification are local and limited, and are not powerful enough to change climate.
“Artificial precipitation enhancement can only be carried out under the right weather conditions, and may increase the amount of rainfall or snowfall by 15 to 25 percent,” he said.
Some scientists remain highly skeptical of the effectiveness of weather modification in increasing rainfall. A meteorologist who refused to be named told Caixin.com, a leading Chinese business news website, “The present technology is incapable of ensuring how much artificial rainfall will be produced. In addition to this, it could be a huge waste of resources if rainfall can’t be consistently maintained.”
Wang said that the cost-benefit ratio of artificial precipitation enhancement is usually around 1:20, and the ratio may vary depending on the type of crop to be protected from drought.
Zhang Peiqun, a researcher with the National Climate Center under the CMA, believes that weather modification is humanity’s way of fine-tuning nature to our own advantage. “Without weather modification, rain might fall in a place without cultivated land or without pressing need for water, whereas with weather modification, clouds can be made to rain over cultivated land that thirsts for rainwater.”
Since late July, Anhui had been parched by drought and temperatures above 35 degrees Celsius. Tens of thousands of people faced shortages of drinking water and large areas of crops were damaged.
It was much needed, for the cost of pumping ground water to irrigate the fields was high.
Yet farmers might not be aware that this 22-52 mm downpour was the result of a weather modification operation carried out by the Fuyang Meteorological Bureau, which had launched cloud seeding rockets to induce precipitation.
Prevalent practice
Weather modification is a frequent practice in China. The number of weather modification operations carried out in the country is the highest in the world, according to the China Meteorological Administration (CMA).
Zheng Guoguang, head of the CMA, said in May that artificial rain enhancement operations had covered more than half of the country’s territory.
Data released by the CMA show that China has carried out nearly 559,000 weather modification operations since 2002, launching more than 900,000 rockets and 8.85 million shells. The effort created an estimated 489.7 billion tons of rainfall.
The country’s weather modification system employs 47,700 people, and has an arsenal including more than 7,034 rocket launchers, more than 50 planes and nearly 6,902 guns.
On August 30, the Chinese Government published a plan, outlining that the country’s aims to build a relatively complete weather modification system by 2020.
The document says that by 2020, China plans to increase precipitation by 60 billion tons annually via cloud seeding, as well as extend the coverage of artificial hail suppression to more than 540,000 square km from the current 470,000 square km, a near 15-percent increase.
“Weather has been modified to relieve drought, prevent forest fire, protect ecological environment, fill reservoirs, ensure good weather for major events, cool down cities and improve urban environment,” said Wang Guanghe, Deputy Director of the Artificial Weather Intervention Center under the CMA.
Commonplace weather modification operations include rainfall adjustment by dispersing a catalyst to the clouds to delay or induce rain as well as measures to suppress hail, dissipate clouds, prevent frost and blunt lightning storms.
According to Yu Ziping, Deputy Chief Engineer of the China Enginery Research Institute, there are two cloud seeding processes: One is to use ice-forming substances such as silver iodide or dry ice to freeze supercooled water droplets in a cold cloud, and the other is to use water-attracting substances such as salt to cause droplets to condense within a warm cloud.
“Catalysts can be dispersed into cloud by planes, guns, rockets and in some circumstances, natural air currents,” Zheng said.
The potential for average artificial rainfall in China could reach up to 280 billion tons per year, which is seven times the storage capacity of the Three Gorges reservoir, the country’s largest.
The CMA said that in the next five years, it will increase the efficiency of artificial rain enhancement by 3 to 5 percent, and expand the operation area of hail suppression by 5 percent.
Past experience
“China generally is dry, so it explores all available measures to increase precipitation,”said Mao Jietai, a professor at the Department of Atmospheric and Oceanic Sciences of Peking University’s School of Physics.
Mao said that drought is a major meteorological disaster that threatens the country’s food and environmental security, and the percapita water availability in China is less than one fourth of the world average.
In addition, hail and heavy fog occur frequently. Official statistics estimate that abnormal meteorological phenomenon have incurred more than 70 percent of all losses caused by natural disasters.
As early as in the 17th century, Chinese people attempted to suppress hail by firing gunpowder from cannons into yellow clouds floating from mountains during the months of May and June, for such clouds were believed to carry hail, according to Yu.
The first successful cloud seeding operation in China took place in 1958 when a plane was used to spread dry ice into clouds to quench a severe drought in northeastern Jilin Province. Thereafter, weather modification technology has developed fast in the country.
During the 2008 Summer Olympic Games in Beijing, weather modification technology was used to deliver a rain-free opening ceremony on August 8.
Historical data indicated a 41-percent possibility of precipitation on that date in Beijing. To prevent rain from ruining the ceremony, the Beijing Meteorological Bureau set up 26 weather control stations in Beijing’s vicinity, hired 32,000 people, and deployed aircraft, rockets and artillery to spread silver iodide crystals and dry ice in clouds 50 km upwind of Beijing, according to the Xinhua News Agency.
Finally, rain-bearing clouds were eliminated before reaching the Bird’s Nest, the nickname for the roofless National Stadium, where the Olympic opening ceremony was staged.
Cloud seeding has also been used before major events to induce a cheerful mood among the population. Beijing was shrouded in cloud and smog in the three days before October 1, 2009, the 60th anniversary of the founding of the People’s Republic of China when a grand military review was scheduled. The weather was depressing. Artificial rain was made in Beijing and neighboring provinces, then on the anniversary day, the parade was held under an exceptionally clear sky.
“Since rain cannot be created from nowhere, accurate weather forecasts and understanding of the clouds’ conditions are required for successful weather modification. Meteorological equipment such as digital radar and microwave radiometer is needed,” Yu said.
China has made steady progress in weather modification technology in the past decades, yet it still lags behind leading countries in the field.
Yu said that so far, the country still imports a significant portion of equipment, and Chinese engineers would like to develop its own advanced equipment to reduce the technology gap between China and leading countries.
Environmental impacts
With the rising use of weather modifica- tion, people are concerned with whether the catalysts added to the clouds will do harm to the environment. Zheng said that the environmental impacts of weather modification are negligible, adding that some of the most common catalysts such as dry ice and liquid nitrogen are naturally present in the air and are not at all harmful.
“Even though silver iodide is used to seed cloud, every shell only contains 1 gram of the chemical, so less than 1 ton of silver iodide is used in a year over a total area of about 5 million square km,” Zheng said.
Artificial rain making has been carried out frequently near Miyun Reservoir, a major drinking water source in suburban Beijing. The office in charge of weather modification under the Beijing Metrological Bureau analyzed the silver iodide level in Beijing’s rainwater and found it too far below the national standard and the standard set by the World Health Organization.
As to whether such operations may impact the global climate, Wang said that the impacts of weather modification are local and limited, and are not powerful enough to change climate.
“Artificial precipitation enhancement can only be carried out under the right weather conditions, and may increase the amount of rainfall or snowfall by 15 to 25 percent,” he said.
Some scientists remain highly skeptical of the effectiveness of weather modification in increasing rainfall. A meteorologist who refused to be named told Caixin.com, a leading Chinese business news website, “The present technology is incapable of ensuring how much artificial rainfall will be produced. In addition to this, it could be a huge waste of resources if rainfall can’t be consistently maintained.”
Wang said that the cost-benefit ratio of artificial precipitation enhancement is usually around 1:20, and the ratio may vary depending on the type of crop to be protected from drought.
Zhang Peiqun, a researcher with the National Climate Center under the CMA, believes that weather modification is humanity’s way of fine-tuning nature to our own advantage. “Without weather modification, rain might fall in a place without cultivated land or without pressing need for water, whereas with weather modification, clouds can be made to rain over cultivated land that thirsts for rainwater.”