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68-589: The king discovered that many areas faced the problem of drought. Over 82% of Thai agricultural land relied on rainfall. Thai farmers were not able to grow crops for lack of water. Although scientific evidence seems to suggest that cloud seeding does not ameliorate droughts, the Royal Rainmaking Project debuted on 20 July 1969 at the king's behest, when the first rainmaking attempt was made at Khao Yai National Park . Dry ice flakes were scattered over clouds. Reportedly, some rainfall resulted. In 1971,

136-474: A crystalline structure like ice. In mid-altitude clouds, the usual seeding strategy has been based on the fact that the equilibrium vapor pressure is lower over ice than over water. The formation of ice particles in supercooled clouds allows those particles to grow at the expense of liquid droplets. If sufficient growth takes place, the particles become heavy enough to fall as precipitation from clouds that otherwise would produce no precipitation. This process

204-576: A cloud seeding project, created in response to lower water levels for hydroelectric power due to dry weather. In February of that year, a group of officials from the SLAF, Ceylon Electricity Board , and meteorology and irrigation departments were sent to Thailand to study rainmaking projects carried out by the Department of Royal Rainmaking and Agricultural Aviation . On March 22, a Harbin Y-12 flew over

272-466: A few experiments at GE's Schenectady Research Lab. 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

340-639: 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 . 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

408-435: A gas, has also been used. It can produce ice crystals at higher temperatures than silver iodide. After promising research, the use of hygroscopic materials, such as table salt , is becoming more popular. When cloud seeding, increased snowfall takes place when temperatures within the clouds are between −20 and −7 °C. Freezing nucleation is induced by the introduction of substances similar to silver iodide, which has

476-552: A haze of ultra-fine dust, the government turned to the DRRAA to seed clouds to create artificial rain over the city. The Pollution Control Department issued warnings that particulate levels had soared to 94 micrograms per cubic metre of air in some areas, far above the safety limit of 50 mcg. The prime minister assured Thais that, "...[rainmaking] should bring some relief at least in the short term,..." Fumes from vehicles, construction sites, and factories in adjacent provinces contribute to

544-472: A long enough time to show statistically any change from natural variations. An attempt by the U.S. military to modify hurricanes in the Atlantic basin using cloud seeding in the 1960s was called Project STORMFURY . Scientists tested four hurricanes across eight days and observed decreased wind speeds of 10% to 30% on four of these days. They originally attributed the lack of results to faulty execution, but

612-515: 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. The hygroscopic material most commonly used is table salt. It is postulated that hygroscopic seeding causes the droplet size spectrum in clouds to become more maritime (bigger drops) and less continental, stimulating rainfall through coalescence. From 1967 to 1972,

680-516: A payload of electric-charge emission instruments and customized sensors that fly at low altitudes and deliver an electric charge to air molecules. This method produced a significant rainstorm in July 2021. For instance, in Al Ain it rained 6.9 millimeters on 20–21 July. An electronic mechanism was tested in 2010, when infrared laser pulses were directed to the air above Berlin by researchers from

748-465: A study to gauge its viability locally. 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

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816-533: Is "difficult to show clearly that cloud seeding has a very large effect". Environmental and health impacts are considered minimal due to the low concentrations of substances used. But concerns persist over the potential accumulation of seeding agents in sensitive ecosystems. The practice has a long history, with initial experiments dating back to the 1940s, and has been used for various purposes, including agricultural benefits, water supply augmentation, and event planning. Legal frameworks primarily focus on prohibiting

884-437: Is exploited in silver-based photography . Silver iodide is also used as an antiseptic and in cloud seeding . The structure adopted by silver iodide is temperature dependent: Silver iodide is prepared by reaction of an iodide solution (e.g., potassium iodide ) with a solution of silver ions (e.g., silver nitrate ). A yellowish solid quickly precipitates . The solid is a mixture of the two principal phases. Dissolution of

952-455: Is known as "static" seeding. Seeding of warm-season or tropical cumulonimbus (convective) clouds seeks to exploit the latent heat released by freezing. This strategy of "dynamic" seeding assumes that the additional latent heat adds buoyancy, strengthens updrafts, ensures more low-level convergence, and ultimately causes rapid growth of properly selected clouds. Cloud seeding chemicals may be dispersed by aircraft or by dispersion devices on

1020-411: Is unable to say with assurance which, if any, seeding techniques produce positive effects. In the 55 years following the first cloud-seeding demonstrations, substantial progress has been made in understanding the natural processes that account for our daily weather. Yet scientifically acceptable proof for significant seeding effects has not been achieved". A 2010 Tel Aviv University study claimed that

1088-486: Is undertaken by dispersing substances into the air that serve as cloud condensation or ice nuclei . Common agents include silver iodide , potassium iodide , and dry ice, with hygroscopic materials like table salt gaining popularity due to their ability to attract moisture. Techniques vary from static seeding, which encourages ice particle formation in supercooled clouds to increase precipitation, to dynamic seeding, designed to enhance convective cloud development through

1156-643: The Eureka organization in 2001 for an invention that is beneficial to the world. In 2009, Jordan received permission from Thailand to use the technique. On 12 October 2005 the European Patent Office granted to King Bhumibol Adulyadej the patent EP 1 491 088 Weather modification by royal rainmaking technology . The budget of the Department of Royal Rainmaking and Agricultural Aviation in FY2019

1224-471: The Maskeliya Reservoir at 8000 feet, dispersing cloud seeding chemicals. Rain arrived the next day on March 23, though project members had expected it to appear earlier on the 22nd. News First proclaimed that the pilot project had "proven to be a success", while Mongabay described it as a "failed attempt" that had "fallen short" and highlighted various climate experts who recommended that

1292-681: The National Oceanic and Atmospheric Administration (NOAA; Department of Commerce). Reclamation sponsored several cloud-seeding research projects under the umbrella of Project Skywater from 1964 to 1988, and NOAA conducted the Atmospheric Modification Program from 1979 to 1993. The sponsored projects were carried out in several states and two countries (Thailand and Morocco), studying both winter and summer cloud seeding. From 1962 to 1988 Reclamation developed cloud seeding applied research to augment water supplies in

1360-504: The University of Geneva . The experimenters posited that the pulses would encourage atmospheric sulfur dioxide and nitrogen dioxide to form particles that would then act as seeds. Whether cloud seeding is effective in producing a statistically significant increase in precipitation is a matter of academic debate, with contrasting results depending on the study in question and contrasting opinion among experts. A study conducted by

1428-491: The haze began in early-August. Johor Water Regulatory Body is focus to produce rain over dams with critically low water levels. They use Cessna 340 with tubes of ioidise salt their operation base is at Senai Airport WMKJ. The Thailand Royal Rainmaking Project ( Thai : โครงการฝนหลวง , RTGS :  khrongkan fon luang ) was initiated in November 1955 by King Bhumibol Adulyadej . Thai farmers repeatedly suffered

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1496-559: The pygmy possum , among other species, as well as recent high-level algal blooms in once pristine glacial lakes. Research 50 years ago and analysis by the former Snowy Mountains Authority led to the cessation of the cloud seeding program in the 1950s with non-definitive results. Formerly, cloud seeding was rejected in Australia on environmental grounds because of concerns about the pygmy possum. The claims of negative environmental impact are disputed by peer-reviewed research, as summarized by

1564-779: The revolution of 1978, in the years 1989 to 1995, cloud fertilization 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. Israel conducted experimental cloud seeding for seven years from 2014 to 2021. The practice involved emitting silver iodide from airplanes and ground stations and took place only in

1632-605: The 2008 Olympic Games in order to have a dry Olympic season. In February 2009, China also blasted iodide sticks over Beijing to artificially induce snowfall after four months of drought, and blasted iodide sticks over other areas of northern China to increase snowfall. The snowfall in Beijing lasted for approximately three days and led to the closure of 12 main roads around Beijing. At the end of October 2009 Beijing claimed it had its earliest snowfall since 1987 due to cloud seeding. According to "research paper from Tsinghua University,

1700-478: The AgI in hydroiodic acid , followed by dilution with water, precipitates β-AgI. Alternatively, dissolution of AgI in a solution of concentrated silver nitrate followed by dilution affords α-AgI. Unless the preparation is conducted in dark conditions, the solid darkens rapidly, the light causing the reduction of ionic silver to metallic. The photosensitivity varies with sample purity. The crystalline structure of β-AgI

1768-662: The Bureau of Reclamation sponsored a six-state research program from 2002 to 2006 called the "Weather Damage Modification Program". A 2003 study by the United States National Academy of Sciences urges a national research program to clear up remaining questions about weather modification's efficacy and practice. In Australia , the Commonwealth Scientific and Industrial Research Organisation (CSIRO) conducted major trials between 1947 and

1836-546: The Chinese government used cloud-seeding techniques to force rainfall the evening before the celebration event. This rainfall lowered the amount of PM2.5 pollution by more than two-thirds. That helped improve the air quality at the time from "moderate" to "good". 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. In

1904-486: The Chinese weather authorities used weather modification to ensure the sky was clear and lower air pollution" on July 1, 2021. The Chinese Communist party celebrated its centenary on July 1 with a major celebration. The celebration took place in Tiananmen Square. The paper was published on November 26, 2021 in a peer-review journal called Environment Science (via South China Morning Post) . The research shows that

1972-475: The Clean Water Act of 1977 and 1987 to establish regulations on this type of pollution." Cloud seeding over Kosciuszko National Park  – a biosphere reserve – is problematic in that several rapid changes of environmental legislation were made to enable the trial. Environmentalists are concerned about the uptake of elemental silver in a highly sensitive environment affecting

2040-626: The Desert Research Institute in Reno, claimed that new technology and research has produced reliable results that make cloud seeding a dependable and affordable water supply practice for many regions. Moreover, in 1998 the American Meteorological Society held that "precipitation from supercooled orographic clouds (clouds that develop over mountains) has been seasonally increased by about 10%." Despite

2108-614: The International Weather Modification Association. In 1891, Louis Gathmann suggested shooting liquid carbon dioxide into rain clouds to cause them to rain. 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

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2176-566: The Law on Water and its Nationalization, 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 fertilized the clouds that were over the Karaj and Jajrud dam area. After

2244-709: The NAS study was acquired in a separate study conducted by the Wyoming Weather Modification Pilot Project, but whereas the NAS study concluded that "it is difficult to show clearly that cloud seeding has a very large effect", the WWMPP study concluded that "seeding could augment the snowpack by a maximum of 3% over an entire season." In 2003, the US National Research Council (NRC) released a report stating, "science

2312-582: The Sierra Nevada of California and a 2004 independent panel of experts in Australia confirmed these earlier findings. "In 1978, an estimated 3,000 tonnes of silver were released into the US environment. This led the US Health Services and EPA to conduct studies regarding the potential for environmental and human health hazards related to silver. These agencies and other state agencies applied

2380-518: The U.S. military's Operation Popeye cloud-seeded silver iodide to extend the monsoon season over North Vietnam , specifically the Ho Chi Minh Trail . The operation extended the monsoon period an average of 30 to 45 days in the targeted areas. The 54th Weather Reconnaissance Squadron carried out the operation to "make mud, not war". One private organization that offered, during the 1970s, to conduct weather modification (cloud seeding from

2448-496: The United States National Academy of Sciences failed to find statistically significant support for cloud seeding's effectiveness. Based on its findings, Stanford University ecologist Jerry Bradley said: "I think you can squeeze out a little more snow or rain in some places under some conditions, but that's quite different from a program claiming to reliably increase precipitation." Data similar to that of

2516-614: The Universities of Wyoming, Washington, UCLA, Utah, Chicago, NYU, Montana, and Colorado, and research teams at Stanford, Meteorology Research Inc., and Penn State University, and the South Dakota School of Mines and Technology, North Dakota, Texas A&M, Texas Tech, and Oklahoma. Cooperative efforts with state water resources agencies in California, Colorado, Montana, Kansas, Oklahoma, Texas, and Arizona assured that

2584-503: The applied research met state water management needs. HIPLEX also partnered with NASA, Environment Canada, and the National Center for Atmospheric Research ( NCAR ). From 2002 to 2006, in cooperation with six western states, Reclamation sponsored a small cooperative research program called the Weather Damage Modification Program. In the U.S., funding for research has declined in the last two decades. But

2652-559: The common practice of cloud seeding to improve rainfall, with materials such as silver iodide and frozen carbon dioxide, seems to have little if any impact on the amount of precipitation. A 2011 study suggested that airplanes may produce ice particles by freezing cloud droplets that cool as they flow around the tips of propellers, over wings or over jet aircraft, and thereby unintentionally seed clouds. This could have potentially serious consequences for particular hail stone formation. In 2016, Jeff Tilley, director of weather modification at

2720-640: The early-1960s: Only the trial conducted in the Snowy Mountains produced statistically significant rainfall increases over the entire experiment. Hydro Tasmania (at the time still known as the Hydro Electric Commission) began experimenting with cloud-seeding over lake catchments in central Tasmania in the early 1960s in order to determine if their electricity-producing dams could be kept at high water levels through cloud seeding. Tasmania proved to be one place where cloud seeding

2788-478: The effects of drought. The king resolved to do something about it and proposed a solution to the dearth of rain: artificial rainmaking , or cloud seeding. The program is run by the Department of Royal Rainmaking and Agricultural Aviation. Thailand started a rain-making project in the late-1950s, known today as the Royal Rainmaking Project . Its first efforts scattered sea salt in the air to catch

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2856-451: The government conduct more research into the project's potential environmental effects before proceeding further. Silver iodide Silver iodide is an inorganic compound with the formula Ag I . The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a grey colouration. The silver contamination arises because some samples of AgI can be highly photosensitive . This property

2924-642: The government established the Artificial Rainmaking Research and Development Project within the Thai Ministry of Agriculture and Cooperatives . The king received recognition for the Royal Rainmaking Project from the EUREKA organization in 2001 for an invention that is beneficial to the world. In 2009, Jordan received permission from Thailand to use the technique. The Department of Royal Rainmaking and Agricultural Aviation (DRRAA)

2992-482: The ground (generators or canisters fired from anti-aircraft guns or rockets ). For release by aircraft, silver iodide flares are ignited and dispersed as an aircraft flies through the inflow of a cloud. When released by devices on the ground, the fine particles are carried downwind and upward by air currents after release. Since 2021, the United Arab Emirates have been using drones equipped with

3060-488: The ground using silver iodide flares) was Irving P. Krick and Associates of Palm Springs, California . They were contracted by Oklahoma State University in 1972 to conduct a seeding project to increase warm cloud rainfall in the Lake Carl Blackwell watershed . That lake was, at that time (1972–73), the primary water supply for Stillwater , Oklahoma , and was dangerously low. The project did not operate for

3128-659: The growing season in Montana, Kansas, and Texas from 1974 to 1979. In 1979, the World Meteorological Organization and other member-states led by the Government of Spain conducted a Precipitation Enhancement Project (PEP) in Spain, with inconclusive results due probably to location selection issues. Reclamation sponsored research at several universities, including Colorado State University,

3196-454: The humidity and dry ice to condense the humidity to form clouds. The project took about ten years of experiments and refinement. The first field operations began in 1969 above Khao Yai National Park . Since then the Thai government claims that rainmaking has been successfully applied throughout Thailand and neighboring countries. The king received recognition for the Royal Rainmaking Project from

3264-507: The military or hostile use of weather modification techniques, leaving the ownership and regulation of cloud-seeding activities to national discretion. Despite skepticism and debate over its efficacy and environmental impact, cloud seeding continues to be explored and applied in regions worldwide as a tool for weather modification. The most common chemicals used for cloud seeding include silver iodide , potassium iodide and dry ice (solid carbon dioxide). Liquid propane , which expands into

3332-818: The mixed scientific results, cloud seeding was attempted during the 2008 Summer Olympics in Beijing to coax rain showers out of clouds before they reached the city in order to prevent rain during the opening and closing ceremonies. Whether this attempt was successful is a matter of dispute, with Roelof Bruintjes, who leads the National Center for Atmospheric Research's weather-modification group, remarking, "we cannot make clouds or chase clouds away". With an NFPA 704 health hazard rating of 2, silver iodide can cause temporary incapacitation or possible residual injury to humans and other mammals with intense or chronic exposure. But several detailed ecological studies have shown negligible environmental and health impacts. The toxicity of silver and silver compounds (from silver iodide)

3400-536: The neighboring countries. On 25 June 2013, hailstones were reported to have fallen over some parts of Singapore. Despite NEA denials, some believe that the hailstones are the result of cloud seeding in Indonesia. In Malaysia, cloud seeding was first used in 1988 for three purposes: filling up dams, lessening the effects of haze, and fighting forest fires. In 2015, cloud seeding was done daily in Malaysia since

3468-437: The northern parts of the country. 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. 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

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3536-503: 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. In January 2019, the Sri Lanka Air Force (SLAF) and Ministry of Power, Energy and Business Development signed an agreement for

3604-538: The pilots the cloud that has a high concentration of super cooled liquid water. The aircraft will find the altitude where the temperatures are about -5 °C. This is the altitude at which the seeding agent is most active. Pakistan has undergone its first-ever artificial rain experiment using cloud seeding, in a move carried out with the help of the United Arab Emirates Punjab Chief Minister Mohsin Naqvi said there

3672-483: The release of latent heat . Methods of dispersion include aircraft and ground-based generators, with newer approaches involving drones delivering electric charges to stimulate rainfall, or infrared laser pulses aimed at inducing particle formation. Despite decades of research and application, cloud seeding's effectiveness remains a subject of debate among scientists, with studies offering mixed results on its impact on precipitation enhancement. Some studies suggest it

3740-468: The results came into question because of the lack of supercooled water in the hurricane and the inability to determine if the effects were due to human intervention or the natural processes of hurricanes. Two federal agencies have supported various weather modification research projects, which began in the early 1960s: The United States Bureau of Reclamation (Reclamation; Department of the Interior) and

3808-512: The smog that contains dust known as particulate matter PM2.5 . "The department will continue to check the weather every day and will make rain as soon as possible", said the prime minister. Cloud seeding Cloud seeding is a type of weather modification that aims to change the amount or type of precipitation , mitigate hail or disperse fog. The usual objective is to increase rain or snow, either for its own sake or to prevent precipitation from occurring in days afterward. Cloud seeding

3876-489: 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

3944-414: 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. Within the month, Schaefer's colleague, the atmospheric scientist Bernard Vonnegut ,

4012-606: The technique is still actively deployed there. The largest cloud seeding system is in the People's Republic of China . They believe that it increases the amount of rain over several increasingly arid regions, including its capital city, Beijing , by firing silver iodide rockets into the sky where rain is desired. There is even political strife caused by neighboring regions that accuse each other of "stealing rain" using cloud seeding. China used cloud seeding in Beijing just before

4080-580: The theory. 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

4148-927: The western U.S. The research focused on winter orographic seeding to enhance snowfall in the Rocky Mountains and Sierra Nevada, and precipitation in coast ranges of southern California. In California Reclamation partnered with the California Department of Water Resources ( CDWR ) to sponsor the Serra Cooperative Pilot Project (SCPP), based in Auburn , to conduct seeding experiments in the central Sierra. The University of Nevada and Desert Research Institute provided cloud physics, physical chemistry, and other field support. The High Plains Cooperative Pilot Project (HIPLEX) focused on convective cloud seeding to increase rainfall during

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4216-463: The years 2003 and 2004 Karnataka government initiated cloud seeding. Cloud seeding operations were also conducted in the same year through US-based Weather Modification Inc. in the state of Maharashtra . The company Srishti Aviation is actively involved in air defense with two Cessna 340 aircraft for its cloud seeding operations. On the ground at the radar facility the Meteorologist assigns

4284-644: Was 2,224 million baht . 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

4352-553: 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 and received a patent in 1975. Both methods were adopted for use in cloud seeding during 1946 while working for GE in

4420-654: Was drizzle in 'at least 10 areas' of Lahore, consistently ranked the most polluted city in the world. In Jakarta , cloud seeding was used to minimize flood risk in anticipation of heavy floods in 2013, according to the Agency for the Assessment and Application of Technology. 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

4488-975: Was established on 15 September 1992, reporting to the Office of the Permanent Secretary for the Ministry of Agriculture and Cooperatives. The budget of the Department of Royal Rainmaking and Agricultural Aviation in FY2019 was 2,224 million baht . DRRAA in 2019 has flown about 6,000 rain seeding flights, up from its yearly average of 5,000 sorties. DRRAA employs 71 pilots who fly 39 cloud seeding aircraft from Royal Rain Operations Centres in Chiang Mai, Nakhon Sawan, Khon Kaen, Rayong, and Surat Thani. The department plans to open new centres in Buriram and Phitsanulok and to hire an additional 44 pilots. In February 2018, with Bangkok suffering under

4556-475: Was highly effective. Various trials were undertaken between 1964 and 2005, and again between 2009 and 2016, but none have taken place since then. Hydro Tasmania also undertook soil and water survey samples and found negligible trace elements of the materials used for cloud seeding (such as silver iodine), and determined it did not have a detrimental effect on the environment. An Austrian study to use silver iodide seeding for hail prevention ran during 1981–2000, and

4624-441: Was shown to be of low order in some studies. These findings likely result from the minute amounts of silver generated by cloud seeding, which are about one percent of industry emissions into the atmosphere in many parts of the world, or individual exposure from tooth fillings. Accumulations in the soil, vegetation, and surface runoff have not been large enough to measure above natural background. A 1995 environmental assessment in

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