Cloud seeding – a weather modification technique, which aims to increase the amount of precipitation, viz. rain and snow, through the introduction of condensation nuclei into certain specific types of clouds, is being increasingly employed by countries to enhance water security in these tough times of climate change. According to the World Meteorological Organization, more than 50 countries have adopted weather modification techniques. These include the United States of America, China, Israel, India, middle-eastern countries, some African countries and some EU countries.
The technique involves airborne or ground-based interventions. The artificially introduced condensation nuclei provide a base for the water vapors to condense upon. In warm clouds convective clouds, where larger parts are warmer than -10 ºC, simple salt is used, while silver iodide is used to initiate ice formation in cold clouds, which are colder than 0 ºC and have supercooled water. The former is called hygroscopic seeding, while the latter is called glaciogenic seeding.
These artificially introduced condensation nuclei compete with natural aerosol particles increasing the cloud’s efficiency of uptake of available liquid water so that it produces larger drops. This triggers the droplet multiplication effect, which enhances rainfall generation.
Here is a brief overview of the use of this technique by a few countries.
UAE launched the cloud seeding program in 2002 and is implemented by its National Center of Meteorology (NCM). According to Gulf News, “The NCM’s cloud seeding division uses a sophisticated weather surveillance radar (WSR), which is responsible for monitoring the atmospheric pressure and cloud formations around the clock.” UAE employs the cloud seeding technique “throughout the year, when seedable clouds are detected.” “The UAE performs about 1,000 hours of cloud seeding on average each year in order to supplement the minimal rainfall it receives.” UAE uses hygroscopic flares and nano-material for cloud seeding. NCM has reported that the cloud seeding salt injected is even less than the amount of its concentration present in the atmosphere, resulting in potentially no side effect. With water security being a major challenge before the country compounded by the development of large cities, such as Dubai and Abu Dhabi and population growth in times of climate change and declining groundwater reserves, cloud seeding is what UAE takes refuge in.
Saudi Arabia initiated the first phase of its cloud seeding operations in 2022 in areas over three cities, including the capital city of Riyadh, according to Arab News. The National Center of Meteorology overlooks the implementation of the cloud seeding program in the Kingdom. Recently, Minister of Environment, Water and Agriculture and the Chairman of the Board of Directors of NCM signed an agreement to buy five aircrafts for the Regional Cloud Seeding Program, as reported by the Arabian News. It was further reported that out of the five aircrafts, four will be utilized for cloud seeding and one aircraft is dedicated for weather and climate research studies. The Kingdom confirmed to Arabian News that it was only the second country in the world to own a research aircraft of the kind. The Regional Cloud Seeding Program was implemented with the aim of increasing precipitation levels, creating new sources of water, increasing green space and intensifying vegetation to face desertification and mitigating drought through qualified national personnel with the highest skill levels. As revealed by the CEO of NCM, the Kingdom has already completed three phases of the program and is preparing to launch the fourth phase, where the program completed 626.67 hours of flight through 190 cloud seeding missions.
The cloud seeding experiments were initiated in Australia around 1947. Various organizations, such as the Snowy Hydro Limited, Hydro Tasmania, oversee the implementation of cloud seeding in Australia. The New South Wales government enacted a law to specify the conditions when cloud seeding is to be undertaken. The Snowy Mountains Cloud Seeding Act, 2004 requires that seeding agent is only to be discharged when precipitation is likely to fall as snow to at least 1400 meters above sea level. According to the reports submitted by Snowy Hydro, the cloud seeding operations take place throughout the cool-season in the months of May and October. The cloud seeding operations are essentially undertaken to increase runoff for production of hydro-electricity and also for drought-relief. Snowy hydro claims that its program increases precipitation by an average of 14%.
The Beijing Weather Modification Office is tasked with the responsibility of weather modification in China. China is said to have the largest cloud seeding program. China utilizes silver iodide rockets and shells for its cloud seeding program. In China the program aims at drought-relief, firefighting, or counteracting severe dust storms. The Yangtze basin was drought-hit with record-low waters in its reservoirs, which posed a major challenge for authorities to maintain power supply with minimum shortages as it battled record-breaking heatwave in 2022. The Hubei province launched an effort to induce rainfall through cloud seeding operations to try rejuvenate the water reservoirs.
Cloud seeding in the United States has been around from the late 1940s, where the first experiments started in 1946. The region of the Upper Colorado River Basin is where the cloud seeding operations are mostly concentrated. Utah and Colorado have been resorting to the technique for over decades. Until recently there was “little certainty” over any positive impact of cloud seeding. However, a study conducted by researchers at University of Colorado and the National Center for Atmospheric Research in Idaho “demonstrate[ed] unambiguously [that] cloud seeding can increase snowfall.” Western States of US are experiencing the worst drought conditions. This had led them to invest in the cloud seeding program in millions. “It’s no cure for drought, but cloud seeding can be an important water management tool.” U.S. Bureau of Reclamation in March this year granted funds to the tune of $2.4 million for cloud seeding in Western States whose rivers feed the parched desert region.
In India, the states of Tamil Nadu, Karnataka and Maharashtra have had cloud seeding operations in the past. Recently, IIT-Kanpur successfully conducted cloud seeding tests. It is being claimed that the success of these tests brings hope to the drought prone region of Bundelkhand in the state of Uttar Pradesh. Earlier, it was proposed that the technology be used to control pollution in the national capital of Delhi. The weather conditions, including lower moisture levels, were cited as reasons by the Central Pollution Control Board for the project to be declared unviable. The Forest Department of Uttarakhand had sought Centre’s advice, revealed an affidavit filed before the High Court, over its proposal to include cloud seeding as a measure to control or douse forest fires. But the Centre had brushed aside cloud seeding as being anything but mere theoretical solution and instead advised to employ other options for mitigation of forest fires. The recent developments provide some hope for the drought prone areas in the northern state of Uttar Pradesh.
The weather modification technique of cloud seeding was prevalent in Israel from the 1950s. Israel conducts the operations only in its northern part. “The recent cloud seeding experiment in northern Israel did not show a significant rainfall increase—unlike the sequence of seeding experiments conducted in Israel in the previous century.” Israel halted its cloud seeding program in 2021 because it seemed to yield only marginal gains in precipitation.
Thailand Royal Rainmaking Project was initiated in 1955. The program is run by the Department of Royal Rainmaking and Agricultural Aviation. Cloud seeding operations were carried out in 2019 in Bangkok to alleviate pollution. The operations were reported to have had considerably reduced the amount of PM2.5 dust particles in the air. In March this year, it was reported that the DRRAA was to induce rainfall to help contain forest fires in western forests of Thailand.
Some governments are rigorously pursuing cloud seeding while others are apprehensive about the technology. The technology is productive only in certain specific weather conditions and renders itself unproductive in all others. For the seeding to be effective there must be clouds prevalent. In the absence of clouds there can be no inducement of rainfall. Studies cannot clearly put forth the actual effectiveness of the technology and also how much water can be produced. There are apprehensions that the downwind side, where the clouds might be expected to reach, might bear the brunt of the technology, though such apprehensions are refuted.
The Middle-east is witnessing a race to adopt the technology and attain expertise, owing much of it to unfounded apprehension of the downwind countries. The technology must be employed with much responsibility. The technology has not been proven to be harmful but, there have also not been any conclusive studies about its absolute success.
The path forward must be traversed carefully and where the dependence on the technology comes at a later stage, countries must direct their energies and resources towards water conservation and mitigation of water consumption. It now remains to be seen whether clouds remain pristine or would cease to be so.