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Cloud seeding

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Cloud seeding can be done by ground generators or planes

Cloud seeding is a form of weather modification in which substances are introduced into existing clouds to influence their physical properties. It is primarily used to attempt to increase precipitation, particularly rainfall or snowfall, but has also been investigated for suppressing hail and dispersing fog. Seeding agents are typically dispersed from aircraft or ground-based generators.[1]

The two principal approaches to precipitation enhancement are glaciogenic seeding and hygroscopic seeding. Glaciogenic seeding introduces ice-forming agents, commonly silver iodide, into clouds containing supercooled water to encourage ice-crystal formation and growth. Hygroscopic seeding introduces water-attracting particles, such as salts, into liquid-water clouds to influence the growth and collision of cloud droplets. Both techniques require suitable atmospheric conditions and existing clouds.[1]

Cloud seeding has been investigated since the 1940s and is used in weather-modification programmes around the world. Its effectiveness varies according to the cloud type, atmospheric conditions and method employed. Observational and statistical evidence indicates that glaciogenic seeding can increase precipitation in suitable wintertime mountain clouds. However, establishing the effects of seeding in other conditions remains difficult because of the natural variability of precipitation. A 2024 assessment by the United States Government Accountability Office found that estimates of additional precipitation in the studies it reviewed ranged from 0% to 20%, while emphasizing substantial uncertainties in the available evidence.[1][2]

Studies of commonly used seeding agents have not identified significant environmental or health impacts at the quantities employed in past operations, although the consequences of substantially expanded use remain uncertain. Other proposed approaches, including electrical charging and laser-assisted condensation, remain experimental and have not been demonstrated to reliably enhance rainfall.[1][2]

Methods

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Glaciogenic seeding

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Ground-based silver iodide generator – Colorado, US

Glaciogenic cloud seeding targets clouds containing supercooled water or mixtures of liquid droplets and ice crystals. It introduces ice-forming agents, commonly silver iodide, to encourage the formation of additional ice crystals. These crystals can grow by accumulating water vapour and collecting supercooled droplets, potentially falling as snow or melting into rain. Dry ice (solid carbon dioxide) has also been used to initiate ice formation by locally cooling cloud air. Seeding agents can be dispersed from aircraft or ground-based generators, but their use requires suitable existing cloud conditions.[3][4]

Hygroscopic seeding

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Hygroscopic cloud seeding introduces water-attracting particles, such as sodium chloride, into clouds containing liquid water. The particles are intended to alter the number and size of cloud droplets and promote their growth through collisions and coalescence. Unlike glaciogenic seeding, this approach does not depend on the formation of ice crystals. It is often investigated in convective clouds, where considerable natural variability makes changes in precipitation difficult to attribute to seeding.[5][6]

Experimental methods

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Electrical charging has been investigated as a possible means of influencing atmospheric droplets. In a 2022 field experiment, researchers found that releasing electrical charge altered the concentration of droplets in naturally occurring fog. The experiment did not establish that the technique could increase rainfall.[7] The World Meteorological Organization stated in 2025 that convincing evidence for the effects of ionization methods at the cloud scale was still lacking.[8]

Researchers have also investigated laser-assisted water condensation, using ultrashort laser pulses to induce particle formation and droplet growth in air. Field experiments demonstrated increased condensation associated with laser-generated filaments, but did not establish that the method could produce additional rainfall.[9][10]

Effectiveness

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The effectiveness of cloud seeding depends on the characteristics of the targeted clouds, atmospheric conditions and the seeding method. Evaluating its effects is difficult because natural precipitation varies substantially, making it challenging to distinguish precipitation caused by seeding from precipitation that would have occurred without intervention. The World Meteorological Organization (WMO) recommends controlled experimental designs supported by physical observations and statistical analysis to establish whether a technique is effective.[11]

Evidence is strongest for the use of glaciogenic seeding in suitable wintertime mountain clouds. During the 2017 Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE), researchers used radar observations and precipitation gauges to identify and quantify snowfall attributable to cloud seeding. A study published in 2020 reported additional precipitation of 0.05–0.3 mm at individual gauges during three observed seeding events. The results demonstrated that cloud seeding could produce measurable snowfall under favourable conditions, although they did not establish its effectiveness for increasing seasonal precipitation across broader regions.[12]

A 2024 assessment by the United States Government Accountability Office found that estimates of additional precipitation in the studies it reviewed ranged from 0% to 20%. However, limitations in the research made the overall effectiveness and benefits of cloud seeding difficult to determine reliably. Cloud seeding also requires suitable existing clouds and cannot generate precipitation in otherwise unsuitable atmospheric conditions.[13]

The effectiveness of other applications, including seeding convective clouds to increase rainfall and suppressing hail, remains less certain. The WMO has noted that the natural variability and complexity of these cloud systems make the effects of seeding particularly difficult to demonstrate. It also cautions that weather-modification technologies cannot create entire rain-producing cloud systems or eliminate severe weather phenomena.[14]

Impact on environment and health

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The environmental and health effects of cloud seeding depend on the substances used, their concentrations and the extent of their application. Research has focused particularly on silver iodide, a commonly used ice-nucleating agent. Silver iodide is poorly soluble in water, limiting the release of dissolved silver ions, which can be toxic to microorganisms and aquatic organisms at sufficiently high concentrations.[15]

According to the World Meteorological Organization (WMO), published studies have not identified significant effects on human health or the environment from the quantities of silver iodide and other commonly used seeding agents employed in past weather-modification operations. A 2024 assessment by the United States Government Accountability Office similarly found that the limited available research suggested no environmental or health concerns at current levels of silver iodide use. However, the assessment emphasized that the effects of substantially more widespread use remain uncertain.[16][17]

Laboratory research has identified adverse effects of silver iodide on some soil bacteria and freshwater organisms under experimental exposure conditions, raising questions about potential effects from repeated applications. Such findings do not establish that ordinary cloud-seeding operations have caused comparable environmental damage.[18] The WMO recommends environmental and health assessments when substantially greater quantities or new seeding agents are proposed. Potential unintended effects on precipitation outside targeted areas also require further investigation.[19]

History

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The Pittsfield Flight; the world's first successful weather modification experiment
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Beech 18 used dry ice for cloud seeding in the early postwar era US
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Lockheed 18 cloud seeding from Wagga Airport in 1958 Australia
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T-28A Trojan rain maker 1960 US
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Curtiss P-40 rain maker 1964 US, now at Yanks Air Museum
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Curtiss P-40N N1232N Weather Modification Company - cloud seeding
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Harvard hail defence 1964 Canada

In 1891, Louis Gathmann suggested shooting liquid carbon dioxide into rain clouds to cause them to rain.[20] During the 1930s, the Bergeron–Findeisen process theorized that supercooled water droplets present, while ice crystals are released into rain clouds, would cause rain. While researching aircraft icing, General Electric (GE)'s Vincent Schaefer and Irving Langmuir confirmed the theory.[21] Schaefer discovered the principle of cloud seeding in July 1946 through a series of serendipitous events. Following ideas he and Langmuir generated while climbing Mt. Washington in New Hampshire, Schaefer, Langmuir's research associate, created a way of experimenting with supercooled clouds using a deep freeze unit of potential agents to stimulate ice crystal growth, i.e., table salt, talcum powder, soils, dust, and various chemical agents with minor effect. Then, on July 14, 1946, he wanted to try a few experiments at GE's Schenectady Research Lab.[22]

He was dismayed to find that the deep freezer was not cold enough to produce a "cloud" using breath air. He decided to move the process along by adding a chunk of dry ice just to lower the temperature of his experimental chamber. To his astonishment, as soon as he breathed into the deep freezer, he noted a bluish haze, followed by an eye-popping display of millions of microscopic ice crystals, reflecting the strong light rays from the lamp illuminating a cross-section of the chamber. He instantly realized that he had discovered a way to change super-cooled water into ice crystals. The experiment was easily replicated, and he explored the temperature gradient to establish the −40 °C (−40 °F) limit for liquid water.[23][24]

Within the month, Schaefer's colleague, the atmospheric scientist Bernard Vonnegut, was credited with discovering another method for "seeding" super-cooled cloud water. Vonnegut accomplished his discovery at the desk, looking up information in a basic chemistry text and then tinkering with silver and iodide chemicals to produce silver iodide. Together with Professor Henry Chessin, of SUNY Albany, a crystallographer, he co-authored a publication in Science[25] and received a patent in 1975.[26] Both methods were adopted for use in cloud seeding during 1946 while working for GE in the state of New York.

Schaefer's method altered a cloud's heat budget; Vonnegut's altered formative crystal structure, an ingenious property related to a good match in lattice constant between the two types of crystal. (The crystallography of ice later played a role in Vonnegut's brother Kurt Vonnegut's novel Cat's Cradle). The first attempt to modify natural clouds in the field through "cloud seeding" began during a flight that began in upstate New York on 13 November 1946. Schaefer was able to cause snow to fall near Mount Greylock in western Massachusetts after he dumped six pounds (2.5 kg) of dry ice into the target cloud from a plane after a 60-mile (100 km) easterly chase from the Schenectady County Airport.[27]

Dry ice and silver iodide agents are effective in changing super-cooled clouds' physical chemistry, and thus useful in augmenting winter snowfall over mountains and, under certain conditions, in lightning and hail suppression. While not a new technique, hygroscopic seeding for enhancement of rainfall in warm clouds is enjoying a revival, based on positive indications from research in South Africa, Mexico, and elsewhere. [citation needed] The hygroscopic material most commonly used is table salt.

From 1967 to 1972, the United States military conducted Operation Popeye, a covert cloud-seeding programme during the Vietnam War. The operation sought to increase monsoon rainfall over the Ho Chi Minh trail and hinder North Vietnamese military transport. However, the programme was not designed to permit a reliable scientific evaluation of its effectiveness, and the extent to which it influenced precipitation remains uncertain. Its disclosure contributed to international concerns about the military use of weather-modification technology.[28]

Project Stormfury (1962–1983) was a United States government research programme that attempted to weaken hurricanes by dispersing silver iodide into clouds outside their eyewalls. The proposed mechanism was intended to stimulate the formation of a larger eyewall and thereby reduce the storm's maximum wind speeds. Although reductions in wind speed were observed following some seeding experiments, subsequent research showed that comparable changes occur naturally through eyewall replacement cycles. Researchers also found that hurricanes generally contain insufficient supercooled water for the proposed seeding mechanism to work. The experiments therefore did not establish that cloud seeding could reduce hurricane intensity.[29][30]

Federal support for cloud-seeding research in the United States expanded during the 1950s and 1960s, with programmes sponsored by the United States Weather Bureau, the United States Air Force and the National Science Foundation. The Bureau of Reclamation subsequently conducted Project Skywater, which investigated whether cloud seeding could augment water supplies in the western United States. Its research included wintertime snowfall enhancement and the High Plains Cooperative Program (HIPLEX), which studied the potential for increasing rainfall from convective clouds in the Great Plains.[31][32]

Federal funding for weather-modification research reached a high point in the mid-1970s before declining. Scientific assessments during this period found that experimental evidence had not conclusively established the effectiveness of cloud seeding for increasing precipitation. In 2003, the National Research Council recommended a coordinated research programme to address continuing uncertainties about atmospheric processes and the evaluation of weather-modification techniques.[33]

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Cloud seeding at Corryong, Victoria Cessna 320 1966

Cloud-seeding research in Australia began in 1947, when the Commonwealth Scientific and Industrial Research Organisation (CSIRO) conducted experiments using dry ice released into cumulus clouds near Sydney. The promising initial observations led to an extended research programme involving laboratory studies and field experiments.[34] Between 1955 and 1963, CSIRO conducted controlled seeding experiments in several regions, including the Snowy Mountains, South Australia, New England and the Warragamba catchment. A 1955–1959 experiment in the Snowy Mountains produced indications of increased precipitation, but its published evaluation concluded that the results were inconclusive.[35]

Later experiments in Tasmania produced stronger statistical evidence of rainfall enhancement under particular meteorological conditions, especially in layered clouds undergoing uplift over mountainous terrain. A 1997 review found evidence of positive effects in two Tasmanian experiments but concluded that the results of most Australian mainland experiments remained inconclusive or disputed.[36] A 2009 reanalysis of Tasmanian rainfall records found a positive statistical association with cloud-seeding operations while emphasizing the need for further observations of cloud microphysics to establish the physical basis of the results.[37]

Operations by country

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Asia

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China

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Xian MA60 cloud seeding aircraft of China Meteorological Administration

China operates extensive weather modification programmes intended to increase rainfall and snowfall and reduce hail damage, using methods that include dispersing seeding agents from aircraft and rockets. The country's meteorological authorities reported conducting rain- and snow-enhancement operations throughout 2021–2025. However, estimates of additional precipitation attributable to cloud seeding remain difficult to establish independently because of natural weather variability and limitations in evaluating operational programmes.[38][39]

Ahead of the opening ceremony of the 2008 Summer Olympics in Beijing, Chinese meteorological authorities launched rockets containing silver iodide into approaching clouds in an attempt to reduce rainfall over the Olympic venues. Although rain did not reach the main stadium during the ceremony, scientists noted the difficulty of determining whether the cloud-seeding operation caused this outcome.[40]

India

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In India, cloud seeding operations were conducted during the years 1983, 1984–87, and 1993–94 by the Tamil Nadu Government due to severe drought.[41] In the years 1999 to 2004, 2006 and 2010 Karnataka government attempted cloud seeding without much success.[42] Cloud seeding operations were also conducted in 2003 and 2004 through in the state of Maharashtra with inconclusive results.[43]

In October 2025, cloud seeding was conducted to improve the air quality over Delhi but the experiment yielded no significant results.[44][45][46]

Iran

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In 1946, the Iranian government tried to fertilize Iran's clouds with the help of Americans, but it was unsuccessful. Then in 1947, in Article 19 of the Law on Water and its Nationalisation, the then Ministry of Water and Electricity was obliged to provide the water needed by the country in various ways, including cloud fertilization. Accordingly, the Ministry of Energy between 1953 and 1957, in cooperation with a Canadian company and using aircraft and silver iodide compound fertilised the clouds that were over the Karaj and Jajrud dam area.[47][48]

After the revolution of 1978, in the years 1989 to 1995, cloud fertilisation was carried out in a scattered manner using ground generators in the heights of Shirkuh, Yazd. Then, with the announcement of the Minister of Energy in February 1996, the National Center for Cloud Fertility Research and Studies was established in Yazd and officially started working in 1997.[47][48]

Israel

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Cessna Skymaster 2015 Israel

Israel conducted experimental cloud seeding for seven years from 2014 to 2021.[49] The practice involved emitting silver iodide from airplanes and ground stations and took place only in the northern parts of the country.[50] Israel stopped the rain enhancement project in 2021 due to the experiment data showing that the practice was largely ineffective and expensive, and because there had been some recent years of unrelated significant rainfall.[49]

Kuwait

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To counter drought and a growing population in a desert region, Kuwait is embarking on its own cloud seeding program, with the local Environment Public Authority conducting a study to gauge its viability locally.[51]

North Korea

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Cloud seeding projects have been carried out in North Korea since the 1960s.[52] Their initial purpose was to ensure a steady supply of water for the hydroelectric power stations located in the South Hamgyong Province. In the following decades, however, while research on utilising cloud resources was carried out, seeding operations themselves were almost nonexistent. Cloud seeding operations were prioritised again in the twenty-first century due to socio-economic requirements, and to mitigate natural disasters such as droughts and hailstorms. More recently, between 2017 and 2020, the Chungsan region was selected to carry out cloud seeding experiments over, which were seen to have enhanced precipitation in the region.[52]

Pakistan

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In December 2023, the government of Pakistan's Punjab province carried out a cloud-seeding operation in Lahore with assistance from the United Arab Emirates, aiming to reduce severe smog. Provincial officials reported drizzle in parts of the city following the operation.[53]

In November 2024, Punjab authorities conducted another experiment using locally developed cloud-seeding technology in Jhelum, Chakwal, Talagang and Gujar Khan. Rainfall was subsequently reported in Jhelum and Gujar Khan. The provincial government described the experiment as successful, although the reports did not establish the extent to which seeding contributed to the observed precipitation.[54]

Sri Lanka

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In 2019, Sri Lanka conducted an experimental cloud-seeding programme intended to increase rainfall in catchment areas supplying hydroelectricity. The project involved the Sri Lanka Air Force and Ceylon Electricity Board, with technical assistance from Thailand.[55]

On 22 March 2019, an aircraft dispersed seeding materials over the Maussakelle reservoir catchment area. Rainfall was observed in the region the following day, but the experiment did not demonstrate that the precipitation resulted from seeding. Authorities subsequently suspended the programme after the initial trial failed to produce the expected results, citing insufficient cloud cover and atmospheric moisture.[56]

United Arab Emirates

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The United Arab Emirates began rain-enhancement operations in 1990. Its National Center of Meteorology conducts cloud-seeding operations using aircraft and ground-based generators, primarily dispersing hygroscopic materials such as salts into suitable clouds. In 2015, the country established the UAE Research Program for Rain Enhancement Science to support research into precipitation enhancement and related technologies.[57]

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Beechcraft King Air C90 used for cloud seeding operations in UAE

Southeast Asia

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In Southeast Asia, open-burning haze pollutes the regional environment. Cloud seeding has been used to improve the air quality by encouraging rainfall. On 20 June 2013, Indonesia said it will begin cloud-seeding operations following reports from Singapore and Malaysia that smog caused by forest and bush fires in Sumatra have disrupted daily activities in the neighbouring countries.[58]

Indonesia

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In Jakarta, cloud seeding was tested in 2013 to minimize flood risk in anticipation of heavy floods, according to the Agency for the Assessment and Application of Technology.[59] The practice has continued up to March 2025, national and provincial disaster agencies used cloud seeding over the sea north of Jakarta, with the aim of shifting rainfall away from land and toward the sea, costing about 200 million rupiahs (US$12,292) for each flyover.[60]

Malaysia

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In Malaysia, cloud seeding was first used in 1988 for three purposes: filling up dams, lessening the effects of haze, and fighting forest fires.[61] In 2015, cloud seeding was done daily in Malaysia since the haze began in early-August.[62] Johor Water Regulatory Body focused to produce rain over dams with critically low water levels. They used Cessna 340 with tubes of ioidised salt, flying from their operation base at Senai International Airport.[63]

Thailand

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Thailand's Royal Rainmaking Project originated in 1955, when King Bhumibol Adulyadej proposed investigating cloud seeding as a means of alleviating agricultural drought. The first field experiments took place in 1969, and a national weather-modification programme was formally established in 1975.[64][65] The programme uses aircraft to disperse seeding agents into suitable clouds in attempts to increase precipitation and augment water supplies, particularly in drought-affected agricultural regions. Although Thai authorities have reported benefits from these operations, determining how much additional rainfall is attributable to seeding remains scientifically challenging.[66]

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CASA C-212 Aviocar of KASET Thailand

Vietnam

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In Vietnam, during the leadup to and initial stages of the Battle of Điện Biên Phủ in 1954, the French Far East Expeditionary Corps looked into the possibility of using cloud seeding to impede Việt Minh flow of supplies through Route Provinciale 41, a dirt road leading into Điện Biên Phủ that would become more difficult to navigate during the rainy season. General Henri Navarre authorized research into using cloud seeding this way on March 16, just before the outbreak of the battle, and a test commenced the following month. Results were disappointing; while it did not take long for the rain clouds to form and release precipitation, they often drifted away from Route Provinciale 41 in the process, reducing their ability to hinder Việt Minh logistics.[67]

North America

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United States

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In the United States, cloud seeding is used to increase precipitation in areas experiencing drought, to reduce the size of hailstones that form in thunderstorms, and to reduce the amount of fog in and around airports. In the summer of 1948, the usually humid city of Alexandria, Louisiana, under Mayor Carl B. Close, seeded a cloud with dry ice at the municipal airport during a drought; quickly 22 mm (0.85 in) of rain fell.[68][better source needed]

Major ski resorts occasionally use cloud seeding to induce snowfall. Eleven western states and one Canadian province (Alberta) had ongoing weather modification operational programs in 2012.[69] In 2006, an US$8.8 million project began in Wyoming to examine cloud seeding's effects on snowfall over Wyoming's Medicine Bow, Sierra Madre, and Wind River mountain ranges.[70]

In Oregon, Portland General Electric used Hood River seeding to produce snow for hydro power in 1974-1975. The results were substantial, but caused an undue burden on the locals, who experienced overpowering rainfall, causing street collapses and mudslides. PGE discontinued its seeding practices the next year.[71]

In 1978, the U.S. signed the Environmental Modification Convention, which bans the use of weather modification for hostile purposes.[72]

As of 2022, seven agencies in California are conducting cloud seeding operations using silver iodide, including the Sacramento Municipal Utility District, which began employing the technique in 1969 to increase the water supply to its hydroelectric power plants, and reported that it results in "an average of 3 to 10% increase in [Sierra Nevada] snowpack".[73]

Canada

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During the sixties, Irving P. Krick & Associates operated a successful cloud seeding operation in the area around Calgary, Alberta. This utilised both aircraft and ground-based generators that pumped silver iodide into the atmosphere in an attempt to reduce the threat of hail damage. Ralph Langeman, Lynn Garrison, and Stan McLeod, all ex-members of the RCAF's 403 Squadron, attending the University of Alberta, spent their summers flying hail suppression. The Alberta Hail Suppression Project is continuing with C$3 million a year in funding from insurance companies to reduce hail damage in southern Alberta.[74]

Europe

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Bulgaria

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Bulgaria operates a hail-suppression programme administered by the Executive Agency for Hail Suppression, established in 1968 under the Ministry of Agriculture. The programme uses weather radar to identify potentially damaging storms and rockets to disperse seeding agents into targeted clouds. Its principal objective is to reduce hail damage to agricultural crops.[75][76]

The effectiveness of cloud seeding for hail suppression remains uncertain. The World Meteorological Organization notes that the complexity and natural variability of hailstorms make the effects of seeding difficult to establish, and that experimental evidence remains insufficient to confirm the proposed mechanisms reliably.[77]

France and Spain

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Cloud seeding began in France during the 1950s with the intent of reducing hail damage to crops. The ANELFA () project consists of local agencies acting within a non-profit organization.[78] A similar project in Spain is managed by the Consorcio por la Lucha Antigranizo de Aragon.[78] The success of the French program was supported by analysis made by Jean Dessens based on insurance data; that of the Spanish program in studies conducted by the Spanish Agricultural Ministry.[78] However, Jean Dessens's results were heavily criticized and doubt was cast on the effectiveness of ground generator seeding. ()

Russia

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The Soviet Union created a specifically designed version of the Antonov An-30 aerial survey aircraft, the An-30M Sky Cleaner, with eight containers of solid carbon dioxide in the cargo area plus external pods containing meteorological cartridges that could be fired into clouds.[79] Russian government spends millions on 'cloud seeding' technology to ensure it doesn't rain on May Day public holiday. A single contractor was hired to employ a technique which involves dispersing clouds and forcing them to rain before the time they naturally would – dropping the rain on other places and at other times, so they don’t affect specific events.[80] In 2020, Russia used cloud seeding to help fight Siberian forest fires.[81] The Russian government has also used cloud seeding technology in Crimea to alleviate drought which was caused as a result of Ukraine blocking the Crimean Canal.[82] Russia published a review of the weather electromagnetic correction technology in 2015, which was developed in the 1980s in the USSR and shares technology with India.[83]

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Partenavia P.68 Hagelflieger - Germany

Germany

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Cessna 210 2006 Austria

In Germany civic engagement societies organize cloud seeding on a region level. A registered society[84] maintains aircraft for cloud seeding to protect agricultural areas from hail in the district Rosenheim, the district Miesbach, the district Traunstein (all located in southern Bavaria, Germany) and the district Kufstein (located in Tyrol, Austria).[citation needed]

Cloud seeding is also used in Baden-Württemberg, a federal state particularly known for its winegrowing culture. The districts of Ludwigsburg, Heilbronn, Schwarzwald-Baar and Rems-Murr, as well as the cities Stuttgart and Esslingen participate in a program to prevent the formation of hailstones. Reports from a local insurance agency suggest that the cloud seeding activities in the Stuttgart area have prevented about €5 million in damages in 2015 while the project's annual upkeep is priced at only €325.000.[85] Another society for cloud seeding operates in the district of Villingen-Schwenningen.[86]

Austria

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Cessna 210B Hagelflieger Austria

Austria has two hail defence organizations: Steirische Hagel Abwehr, with four aircraft: Cessna 182 and Südflug with three aircraft: Cessna 150L, Cessna 182P, Partenavia P.68 at Graz Airport.[87]

Slovenia

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In northeastern Slovenia, aircraft-based cloud seeding has been used in an attempt to reduce damage from hail. The programme involves dispersing silver iodide into thunderstorm clouds and has been carried out by Letalski center Maribor with support from national and local authorities.[88][89]

The programme's effectiveness remains scientifically unproven. The Slovenian Environment Agency has stated that research has not established a statistically reliable reduction in hail from such operations. The continuation of the programme has been debated by meteorologists, agricultural representatives and government officials.[90][91]

United Kingdom

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Project Cumulus was a UK government initiative to investigate weather manipulation, in particular through cloud seeding experiments, operational between 1949 and 1952. A conspiracy theory has circulated that the Lynmouth flood of 1952 was caused by secret cloud seeding experiments carried out by the Royal Air Force.[92][93] However, meteorologist Philip Eden has given several reasons why "it is preposterous to blame the Lynmouth flood on such experiments".[94][95]

Australia

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Cessna 441 Conquest II used to conduct cloud-seeding flights in the Australian state of Tasmania

Australia has conducted cloud-seeding operations primarily to increase precipitation in hydroelectric catchments. Two major programmes were operated by Hydro Tasmania and Snowy Hydro Limited.

Hydro Tasmania used aircraft-based cloud seeding to supplement rainfall in catchments supplying hydroelectric reservoirs. The programme was suspended in June 2016 following public concern about a seeding flight conducted shortly before severe flooding. Subsequent assessments found that the flight did not affect precipitation or contribute to the flooding. Hydro Tasmania did not resume operations in 2017, pending further review and public consultation.[96][97]

In the Snowy Mountains, Snowy Hydro began a cloud-seeding trial in 2004 to investigate increasing snowfall and subsequent water availability for hydroelectric generation. The programme transitioned to regular operations in 2013, using ground-based generators to disperse silver iodide into suitable winter clouds. Operations continued through 2023 but were paused in 2024 for an economic review. On 30 May 2025, Snowy Hydro announced the programme's permanent cessation, citing rising operating costs, ageing equipment and regulatory expenses that outweighed its anticipated benefits.[98][99]

Africa

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Alpha jet 2014 Morocco

In Mali and Niger, cloud seeding is also used on a national scale.[100][101] It has also been used between 1999 and 2002 in Burkina Faso and from 2005 in Senegal. Cloud seeding experiments and operations were also conducted in Rhodesia (now Zimbabwe) between 1968 and 1980.[102]

Morocco

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In 1985 the Moroccan Government started with a Cloud seeding program called 'Al-Ghait'. Morocco utilizes an active weather modification initiative known as Programme Al Ghait, which artificially enhances rainfall through cloud seeding to combat severe, persistent droughts. Originally established in 1984 in collaboration with the United States, the Moroccan government has significantly ramped up funding and infrastructure for the program.

Regulation

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The Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD), which entered into force in 1978, prohibits participating states from using environmental modification techniques for military or other hostile purposes when their effects are widespread, long-lasting or severe. The convention does not prohibit weather modification for peaceful purposes.[103]

Regulation of civilian cloud seeding varies between jurisdictions. In the United States, the Weather Modification Reporting Act of 1972 requires operators to report weather-modification activities to the National Oceanic and Atmospheric Administration (NOAA). Regulations generally require an initial report at least ten days before operations begin. NOAA maintains records of these activities but does not approve or regulate cloud-seeding operations.[104][105]

Misinformation

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Cloud seeding has been associated with conspiracy theories alleging that governments or private organizations can deliberately create or manipulate major weather disasters. Following Hurricane Helene and Milton in 2024, false claims circulated that weather-modification technologies had been used to create or steer the storms.[106] Similar unfounded claims attributed the July 2025 Central Texas floods to cloud-seeding operations, despite meteorological evidence that the operations could not have caused the flooding.[107]

The World Meteorological Organization states that weather-modification technologies cannot create entire rain-producing cloud systems or control large-scale atmospheric conditions. The National Oceanic and Atmospheric Administration similarly states that no existing technology can create or steer hurricanes.[108][109]

See also

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References

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  1. 1 2 3 4 "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  2. 1 2 Cloud Seeding Technology: Assessing Effectiveness and Other Challenges (Report). U.S. Government Accountability Office. 19 December 2024. Retrieved 22 October 2026.
  3. ↑ Rauber, Robert M.; Zaremba, Troy J. (2025). "Intentional Weather Modification". Encyclopedia of Atmospheric Sciences. Elsevier. doi:10.1016/B978-0-323-96026-7.00100-4.
  4. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  5. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  6. ↑ Rauber, Robert M.; Zaremba, Troy J. (2025). "Intentional Weather Modification". Encyclopedia of Atmospheric Sciences. Elsevier. doi:10.1016/B978-0-323-96026-7.00100-4.
  7. ↑ Harrison, R. Giles; Marlton, Graeme J.; Ambaum, Maarten H. P.; Nicoll, Keri A. (2022). "Modifying natural droplet systems by charge injection". Physical Review Research. 4 (2): L022050. doi:10.1103/PhysRevResearch.4.L022050.{{cite journal}}: CS1 maint: article number as page number (link)
  8. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  9. ↑ Rohwetter, Philipp; Kasparian, Jérôme; Stelmaszczyk, Kamil (2010). "Laser-induced water condensation in air". Nature Photonics. 4: 451–456. doi:10.1038/nphoton.2010.115.
  10. ↑ Henin, Stefano; Petit, Yannick; Rohwetter, Philipp (2011). "Field measurements suggest the mechanism of laser-assisted water condensation". Nature Communications. 2: 456. doi:10.1038/ncomms1462.
  11. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  12. ↑ Friedrich, Katja; Ikeda, Kyoko; Tessendorf, Sarah A.; French, Jeffrey R.; Rauber, Robert M.; Geerts, Bart (2020). "Quantifying snowfall from orographic cloud seeding". Proceedings of the National Academy of Sciences. 117 (10): 5190–5195. doi:10.1073/pnas.1917204117. PMID 32094189.
  13. ↑ Cloud Seeding Technology: Assessing Effectiveness and Other Challenges (Report). U.S. Government Accountability Office. 19 December 2024. Retrieved 22 October 2026.
  14. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  15. ↑ Cloud Seeding Technology: Assessing Effectiveness and Other Challenges (Report). U.S. Government Accountability Office. 19 December 2024. Retrieved 22 October 2026.
  16. ↑ "WMO Statement on Weather Modification". World Meteorological Organization. 14 June 2025. Retrieved 22 October 2026.
  17. ↑ Cloud Seeding Technology: Assessing Effectiveness and Other Challenges (Report). U.S. Government Accountability Office. 19 December 2024. Retrieved 22 October 2026.
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Further reading

[edit]
  • Schaefer, Vincent J. Serendipity in Science: My Twenty Years at Langmuir University 2013 Compiled and Edited by Don Rittner. Square Circle Press, Voorheesville, NY ISBN 978-0985692636
    • Note: Chapter Six "The War Ends as I Discover Cloud Seeding" Schaefer discusses the conversations with Langmuir while climbing Mount Washington (pp. 118–119) and then describes the event "My Discovery of Dry Ice Seeding" on pp. 128–129. References by his son, James M Schaefer, Ph.D.
[edit]
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