The Tsinghua university study found that officials shot rockets of silver iodine into the air to induce artificial rainfall in the hours before the ceremony
China manipulated its weather to ensure low air pollution and blue skies for the Communist Party’s anniversary celebrations, a new study has found
Published in the Environmental Science journal, the Beijing university study found that China used cloud-seeding technology in the hours before a Tiananmen Square ceremony celebrating 100 years of the Communist Part’s rule, to reduce excessive levels of air contamination.
Cloud-seeding technology adds chemicals like small particles of silver iodide to clouds, which prompts water droplets to cluster among them, inducing precipitation. As the rain or snow is created and falls to the ground, they bring down particles contributing to air pollution with them, thus cleansing the air.
The study, authored by the Tsinghua university in Beijing, found that officials shot rockets of silver iodine in to the air to induce artificial rainfall. The rainfall in turn, reduced the amount of fine particulate matter (PM2.5) in the air by two-thirds. As the rain was the only disruptive event in that period, there could have been no other reason why the pollutions levels dropped, the study added.
Residents in nearby mountain regions told the South China Morning Post that they saw the rockets shoot into the sky on June 30.
The centenary celebration had faced unprecedented challenges, according to study authors, including an unexpected rise in air pollution levels and an overcast sky during one of China’s wettest summers on record.
Despite halting all industrial activity in nearby regions, the slow air circulation couldn’t dissipate the pollution fast enough, the study said.
China has long been a proponent of cloud-seeding, investing in the technology far more than most other countries, despite questions over how effective it is and the kind of impact the technology could have on neighbouring weather systems.
In the past five years since 2017, state media has claimed that China spent over US 1.3 billion on the technology and had induced about 233.5 billion cubic metres of additional rain. The practices had also helped reduce 70 per cent of hail damage annually in agricultural regions of Xinjiang, officials said in 2019, according to the Guardian.
The weather modification technique usually accompanies social changes following the shutdown of factories, construction, other polluting industries as well as encouraging people to stay off the streets or leave a region, Dr Shiuh-Shen Chien, of National Taiwan University’s department of geography, wrote in a 2019 essay for Society+Space.
It has also been used to modify the weather for political and international events, including the 2008 Olympics, the 2014 APEC summit, National Day parades and annual Two Sessions meetings.