Inkstone
    Mar
    27
    2018
    Mar
    27
    2018
    The cloud seeding system bringing rain to the Tibetan plains
    The cloud seeding system bringing rain to the Tibetan plains
    SCIENCE

    The cloud seeding system bringing rain to the Tibetan plains

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    by
    Stephen Chen
    Stephen Chen
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    One of China’s biggest defense contractors is developing a huge weather modification project to bring much more rain to the drought-plagued Tibetan Plateau, which is the source of water for much of Asia.

    The system could increase rainfall in an area three times the size of California by as much as 350 billion cubic feet a year, which is about 7% of China’s total water consumption.

    The Tibetan Plateau is the source of most of Asia’s biggest rivers -- including the Yellow River, the Mekong and the Brahmaputra. Billions of people depend on the rivers for their livelihoods.

    The Tibetan plateau has an average altitude of 14,800 feet, and drought is a real risk.
    The Tibetan plateau has an average altitude of 14,800 feet, and drought is a real risk. Photo: Alamy

    But the plateau region is also one of the driest places on Earth. And climate simulations suggest it is likely to experience severe periods of drought in the coming years, due to global warming.

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    Enter Sky River: a project being developed by the China Aerospace Science and Technology Corporation, a state-owned company that is a major space and military contractor.

    Sky River features a massive network of fuel-burning chambers installed at locations across the plateau. The chambers will burn fuel to release silver iodide into the air, in order to produce rain.

    Monsoon winds from India push silver iodide particles into atmosphere, creating clouds which then make rain. Illustration: Cena Lau
    Monsoon winds from India push silver iodide particles into atmosphere, creating clouds which then make rain. Illustration: Cena Lau

    “The data we have collected show very promising results,” a researcher working on the project told the South China Morning Post. “More than 500 burners have been deployed on alpine slopes in Tibet, Xinjiang and other areas.” The researcher didn’t want to give his name as testing is still underway.

    The idea behind Sky River isn’t new (the US has tested it before), but China is the first to try it on such a large scale.

    The technology behind the project was initially developed as part of the Chinese military’s weather modification program. Efforts to employ the technology for civilian use began more than a decade ago, the researcher said.

    It has proved hard to keep the weather modification system burning at high altitudes.
    It has proved hard to keep the weather modification system burning at high altitudes. Photo: xjqx.cn

    A major challenge was keeping the chambers burning in their harsh, low-oxygen environment: the Tibetan Plateau has an average altitude of some 14,800 feet.

    “In our early trials, the flame often extinguished midway,” according to the researcher, adding design improvements mean the chambers can now keep burning for months or even years.

    A smartphone app would be able to keep the whole system running, he said.

    In March, China Aerospace signed an agreement with the prestigious Tsinghua University and the Qinghai government to set up the ambitious project. However, Sky River yet to be approved by the Chinese government, and no launch date has been announced.

    Researchers are also still debating whether the fuel-burning chambers or cloud-seeding planes should be used.

    A burning chamber in operation.
    A burning chamber in operation. Photo: maduo.gov.cn

    Ma Weiqiang, a researcher with the Chinese Academy of Sciences’ Institute of Tibetan Plateau Research, said project was unprecedented in scale, but questioned its effectiveness.

    “I am sceptical about the amount of rainfall they can produce. A weather system can be huge. It can make all human efforts look vain,” Ma said.

    Beijing may decide not to go ahead with it, he added, as collecting moisture in the skies over Tibet could cause a reduction in rainfall in other Chinese regions.

    STEPHEN CHEN
    STEPHEN CHEN
    Stephen is a contributor to Inkstone. He covers science and its impact on society, as well as the environment, military, geopolitics and business for the South China Morning Post.

    STEPHEN CHEN
    STEPHEN CHEN
    Stephen is a contributor to Inkstone. He covers science and its impact on society, as well as the environment, military, geopolitics and business for the South China Morning Post.

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