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What is cloud seeding?
How cloud seeding works. Photo by DooFi-Wikimedia Commons. via Mongabay India

What is cloud seeding?

by Sahana Ghosh on 1 August 2019
Dreaming of a perfect blue-sky and rain-free wedding day? A luxury travel company promises to do just that for a price with the help of cloud seeding, a commonly used technique in weather modification. By artificially popping up clouds a day before the D-day and making it rain, the company guarantees a flawless cloud-free wedding day. Cloud seeding was reportedly deployed in the Duke and Duchess of Cambridge’s wedding in 2012 and in the 2008 Beijing Olympics to prevent rain during the opening and closing ceremonies.
But the technology behind this recent luxury wedding trend is hardly new. Most importantly it is linked to processes that determine our planet’s and our own wellbeing.
For decades, parched nations, from Mali to Thailand have turned to cloud seeding to summon rainfall amid searing temperatures, water shortages and droughts as also to prevent devastating hailstorms.
In the Rocky Mountains, Sierra Nevada and other mountainous areas of the United States, cloud seeding has been employed since the 1950s. China has had a perceived dependency on cloud seeding in dry regions.
The United Arab Emirates has been using cloud seeding since the 1990s and is considered a leader in rain enhancement technology, pumping USD 5 million into the UAE Research Program for Rain Enhancement Science (UAEREP) in 2015.
So what exactly is cloud seeding?
Cloud seeding is a way to artificially tweak rain. It is also known by other terms such as man-made precipitation enhancement, artificial weather modification, rainmaking and so on.
The technology sprays particles of salts like silver iodide and chloride on clouds using a special aircraft, rockets or from dispersion devices located on the ground.
These salt particles act as a core (cloud condensation nuclei or ice-nucleating particles) which draw water vapour within the cloud towards them and the moisture latches on, condensing into water droplets leading to the formation of raindrops.
The goal of cloud seeding is to alter the natural development of the cloud to enhance precipitation, suppress hail, dissipate fog, or reduce lightning.
Rainmaking has its roots in 1946 when American scientists Vincent Schaefer and Bernard Vonnegu at General Electric (GE) successfully seeded a cloud with dry ice and then watched the world’s first artificial snowfall from its base.
According to the company, Schaefer and GE test pilot Curtis Talbot climbed into a small Fairchild plane and tried to seed with dry ice a cloud floating above Schenectady in New York, United States. Schaefer was known as the Snow Man ever since. The team kept working and Bernard Vonnegut improved on the method by using silver iodide, a substance whose crystals are structurally similar to ice, to induce snow.
Since then, global scientific research and development have made cloud seeding a popular method of rain enhancement, including in the world’s most arid regions.
Most cloud seeding activities are being undertaken primarily in response to cries of water shortages affecting agriculture and other societal needs, found a 2017 survey of World Meteorological Organisation members involved in weather modification.
At least 56 countries, including India, have active cloud seeding programs.
Is anyone doing cloud seeding in India?
Six years after Schaefer flew into a cloud lacing it with dry ice, India, post-Independence sowed the seeds in the field of rainmaking.
In 1952 late climatologist S. K. Banerji, the first Indian director-general of Indian Meteorological Department experimented with cloud seeding with salt and silver iodide through hydrogen-filled balloons released from the ground.
Tata firms also took stabs at cloud seeding in the Western Ghats region in 1951 using ground-based silver iodide generators. The Rain and Cloud Physics Research (RCPR) unit of Indian Institute of Tropical Meteorology (IITM) in Pune carried out randomized warm cloud modification experiments through salt seeding during 1957-1966 in north India. Over the next three decades, India experimented in this direction in Maharashtra, Karnataka and Uttar Pradesh.
Research on cloud seeding in India received a boost since 2018 with the Union Ministry of Earth Sciences investing in data collection and experiments.
Research by the IITM in Pune, especially over the last two years (2018 and 2019) will result in a white paper with the scientific facts on the ground for cloud seeding, should states wish to take it up as a measure to increase rainwater.
Read more on how cloud seeding is catching on in India.
While the Union Ministry of Earth Sciences has no plans to have a national programme on cloud seeding, it has already spent Rs 45 crore on research in 2018. In 2019, the work will continue, costing a total Rs 100 crore.
The IITM has initiated a national level campaign designed to make progress in aerosol and cloud microphysics observations over the Indian region, which can be used to propose guidelines for cloud seeding. The project called the Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) will be focussing on aerosol-cloud-precipitation interactions in the pre-monsoon and monsoon environment
Beset by drought and water crisis following deficient rainfall Maharashtra and Karnataka are gearing up for cloud seeding this year. The country received 17 percent less rain than average since the advent of the monsoon on June 1.
What is the impact of cloud seeding?
Despite increasing popularity, there are a lot of unknowns with cloud seeding. The success of the technology and its long term impacts are still debated by scientists.
In 2003, the United States’ National Research Council (NRC) report on Critical Issues in Weather Modification Research highlighted the need to address key uncertainties in our understanding of cloud seeding. Studies have called for investigations into the efficacy of cloud seeding and to quantify cloud seeding impact.
For instance, a recent attempt to induce rain amid a prolonged drought in Sri Lanka has fallen short, drawing criticism, with experts calling for scientific assessments before expensive long-term programs are envisaged. But that hasn’t stopped the government from embracing the project
Read more on cloud seeding in Sri Lanka
In the United Arab Emirates, heavy rainfall triggered by cloud seeding is said to have led to road accidents.
But researchers are also soldiering on, looking into drones, nanotechnology and other disciplines to shore up cloud seeding science. Experts believe as climate change plays truant with rainfall and brings hotter conditions to different parts of the world, governments will be on the lookout for newer and better technologies to cool things down. – Mongabay India

What is cloud seeding?

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