1. Commanding the elements: Cloud seeding and the atmospheric gold rush
Throughout most of history, the weather has been viewed as an unyielding condition beyond the influence of humans. Early civilizations ascribed atmospheric phenomena to the will of higher powers. Whether Zeus, Thor, Raijin, or the Thunderbird, cultures around the globe had myths and legends of deities that summoned lightning from the sky (Elsom 2015). The link between weather and divine providence was so ingrained in European belief that Benjamin Franklin’s invention of the lightning rod in the early 1750s was condemned as interfering with the will of God (Krider 2004). As modern meteorology began to link weather to underlying physical laws and forces, this scientific understanding of the atmosphere only served to reinforce, in its own contemporary way, the belief that the weather was governed by larger foundational processes beyond human control. However, by the late 1940s, this perspective had radically changed.
On 12 July 1946, Vincent J. Schaefer of the General Electric Research Laboratory made a serendipitous discovery that would alter the course of experimental atmospheric science for decades to follow. Under the supervision of Dr. Irving Langmuir, recipient of the 1932 Nobel Prize in chemistry, Schaefer had found a laboratory method to artificially initiate the transformation of supercooled water droplets into ice crystals using dry ice (Schaefer 1946; Blanchard 1996). Several months of research and development by Schaefer, Langmuir, and their colleagues at General Electric culminated in the first of a series of historic cloud seeding experiments, during which 6 pounds of crushed dry ice was dropped by aircraft into a supercooled stratus deck above Pittsfield, Massachusetts (Schaefer 1948; Havens 1952). The result of this field experiment was unambiguous—ice nucleation began immediately upon seeding, resulting in ice crystal growth at the expense of surrounding liquid cloud droplets (Schaefer 1946, 1948; Havens 1952). The cloud dissipated, and snow began to fall. These experiments were repeated numerous times over subsequent years, each providing visual proof of the capability for on-demand cloud glaciation and snow production in supercooled stratiform clouds (Fig. 1; Havens 1952). For the first time in history, precipitation fell at the command of a human.
Aerial photograph taken 24 Nov 1948 above a dissipating supercooled stratus cloud layer over Rome, New York, immediately following dry-ice seeding during flight No. 53 of Project Cirrus. The rectangular “racetrack” seeding pattern measures approximately 20 mi long by 5 mi wide.
Citation: Bulletin of the American Meteorological Society 105, 11; 10.1175/BAMS-D-24-0109.1
The prospect of directly influencing meteorological processes fundamentally changed how scientists of the era viewed the weather. Schaefer’s work opened new avenues of applied atmospheric science, holding the promise of alleviating some of humanity’s most pressing challenges. With the support and advocacy of Langmuir, technical innovation within the General Electric Research Laboratory progressed rapidly. In particular, the discovery of a new glaciogenic compound, silver iodide, by Dr. Bernard Vonnegut provided an alternative that quickly replaced dry ice for cloud seeding applications (Vonnegut 1947). In 1947—less than a year after Schaefer’s first seeding demonstration—General Electric received joint support from the U.S. Army, Navy, and Air Force to begin Project Cirrus, a research study of cloud particles and their modification (Havens 1952). A frenzy of optimism, interest, and technical investment rapidly spread across government agencies and commercial industry as organizations began envisaging applications for this new science. In 1953, at the direction of the U.S. President and Congress, a broad interagency Advisory Committee on Weather Control was established to recommend a national approach for weather modification research, operations, and regulation (Orville 1958). Ultimately the Committee suggested a vigorous increase in government sponsorship of meteorological research efforts to be undertaken by government agencies, universities, industry, and other organizations, with central coordination by the U.S. National Science Foundation (Orville 1958).
By 1959, the National Science Foundation had begun sponsoring a broad portfolio of cloud seeding activities, including experimental hail suppression techniques for agricultural crop protection (Borland et al. 1977). Shortly after, the U.S. Bureau of Reclamation began a large rainmaking program (Project Skywater; Silverman 1976) with the aim of extending growing season precipitation, filling reservoirs, and supplementing winter snowpack. During this period, several efforts in fog dissipation were initiated by the U.S. Air Force (Project Cold Cowl; Appleman 1968; Downie and Silverman 1959) and National Aeronautics and Space Administration (NASA; Project Fog Drops; Kocmond and Jiusto 1968) to support aviation safety and runway visibility. Perhaps the most ambitious cloud seeding program was a joint effort by the U.S. Navy and Department of Commerce in an attempt to steer hurricanes away from the American coastline (Project Stormfury; Gentry 1969; Willoughby et al. 1985). Cloud seeding activity was so intensive that at its peak in the early 1950s, approximately 10% of the U.S. land area was under some kind of weather modification program (Borland et al. 1977). This surge of scientific ambition was exemplified in President John F. Kennedy’s 1961 address to the United Nations, where he stated, “We shall propose further cooperative efforts between all nations in weather prediction and eventually weather control” (List 2004). It was from within this wave of interest that the U.S. Forest Service took their fight against wildfires into the clouds.
2. An ounce of prevention: The lightning fire problem and Project Skyfire
In February of 1948, Schaefer was visited by Harry T. Gisborne, Chief of the Division of Fire Research at the U.S. Forest Service, about their ongoing problem with lightning-ignited forest fires (Schaefer 1949). Unlike human-caused fires—which often occurred in highly traveled areas where detection was rapid and ground-based firefighting response was straightforward—lightning could ignite fires in remote areas far from roads and trails. Making up around 75% of ignitions in the northern Rocky Mountains, lightning-ignited fires in these inaccessible locations were often slow to be detected and difficult to manage by traditional firefighting. Inspired by stories of Schaefer’s rainmaking capabilities, Gisborne was interested in the prospect of using cloud seeding to produce soaking rains to extinguish wildfires from above (Schaefer 1949). After considering the particular difficulties and expense associated with managing lightning-ignited fires, Schaefer suggested that cloud seeding may provide a far greater benefit by preventing fire ignition outright through lightning suppression (Schaefer 1949; Fig. 2, top left).
The genesis of a national research program for lightning suppression. (top left) Cover page of Schaefer’s initial report speculating on the potential of using dry-ice cloud seeding to suppress lightning production over fire-prone areas (Schaefer 1949). (top right) Cover page of the initial progress report of Project Skyfire (Barrows et al. 1954). (bottom right) Cover page of the Project Skyfire training manual given to the field observers who were tasked with recording cloud and lightning activity from their spotter towers (MacCready et al. 1955).
Citation: Bulletin of the American Meteorological Society 105, 11; 10.1175/BAMS-D-24-0109.1
Although the exact physical basis for lightning production was unknown at the time, scientists generally agreed that the presence of supercooled water within the cloud was associated with storm electrification (Schaefer 1949; MacCready 1959). Cloud seeding was designed to transform a cloud’s supercooled water content into the ice phase and as a side effect could potentially eliminate the means of electric charge production (Schaefer 1949). On 16 June 1949, Gisborne led the first field attempt at lightning suppression using dry ice seeding. The trial flight delivered around 50 pounds of dry ice by C-47 aircraft into orographic cumulus over Missoula, Montana, and revealed some of the general logistical challenges of the technique (Schaefer 1977). Nevertheless, this early attempt would soon lead to the development of a national program on lightning modification: Project Skyfire.
The summer of 1953 began the first field season of Project Skyfire, a U.S. national science campaign for understanding the characteristics of thunderstorms and lightning-ignited forest fires (Barrows et al. 1954; Schaefer 1955; Fig. 2, top right). Weather-sensing technology at the time was relatively primitive, and the research program primarily relied on trained observers to document visual observations of clouds, lightning, and ignition points from a network of forest fire look-out stations across the northern Rocky Mountains (Arnold 1964; Barrows 1968; MacCready et al. 1955; Fig. 2, bottom right). By the late 1950s, Project Skyfire had attracted interagency buy-in spanning government (the President’s advisory committee on weather, U.S. Department of Agriculture, Forest Service, National Park Service, Weather Bureau, Bureau of Land Management), nonprofit organizations (Munitalp Foundation), industry (General Electric, Boeing Airplane Company), and academia (e.g., University of Washington, Montana State University), representing a broad coalition of scientists united in their effort to solve the lightning fire problem (Barrows et al. 1954; MacCready et al. 1955; Barrows 1968). Although unknown to American scientists at the time, 1953 also saw Soviet scientists beginning their own field experiments in an effort to use cloud seeding to prevent storm electrification (Imyanitov 1957; Battan 1959). Engineered lightning suppression had truly become an international endeavor.
The first of Project Skyfire’s randomized lightning modification experiments was conducted over the San Francisco peaks north of Flagstaff, Arizona, in 1956 (Barrows 1968). In an attempt to determine statistically whether seeding had any impact on storm electrification, days with likely thunderstorm activity were identified and randomly assigned a “seed” or “no-seed” designation. Based on this random assignment, either all or none of the clouds within the local test area were seeded with silver iodide. The program used both ground-based and airborne seeding systems to deliver plumes of ice-forming nuclei composed of silver iodide smoke particles into developing orographic cumuli (Barrows 1968). A second round of experiments was performed during 1956–1959 over the Bitterroot Mountains on the Idaho–Montana border following the same methods (Barrows 1968). Unfortunately, these initial efforts did not generate sufficient sample sizes to yield definitive conclusions.
The procedure was replicated twice again in 1960 and 1961 over the Deerlodge National Forest near Philipsburg, Montana. The 2 years of observations yielded a small sample size of 18 pairs of seeded–unseeded days. Although lacking statistical significance, the program reported 38% fewer cloud-to-ground lightning strikes on seeded days, with the probability of this occurring by chance around 25% as shown by a two-sided test (Arnold 1964). In an effort to build a stronger link between seeding and altered lightning activity, further experiments were conducted in western Montana spanning 1965–67. Taking individual storms as the sample unit, and comparing 12 seeded to 11 unseeded storms, Baughman et al. (1976) linked silver iodide seeding to decreases in the frequency and duration of lightning activity, as well as alterations in the characteristics of lightning strikes. As reported in the study, seeding reduced the frequency of cloud-to-ground lightning by more than half and decreased the duration of electrical current flow (the mechanism most associated with wildfire ignition) by around one quarter (Baughman et al. 1976). Additional background material on Project Skyfire and lightning-ignited fires is provided by Latham and Williams (2001).
Despite this glimmer of hope among otherwise inconclusive results, Project Skyfire’s field efforts concluded after the 1973 season, with agency funding ending in 1977 (Changnon and Lambright 1987). Questions remained regarding the statistical significance of the field campaign results, which even after five seasons still suffered from few pairs of experimental samples (Battan 1967). The final deathblow did not come solely from a lack of statistical evidence, but rather the risk of cloud seeding operations changing the distribution of rainfall. The Department of Agriculture ultimately concluded that seeding clouds in one area could potentially cause thunderstorms to “rain out” and dissipate at the seeding site, thereby denying farms, forests, and ranches farther downwind of rain that they would have otherwise received (Smith 2017; Dennis 1980, p. 220). By the end of the 1970s, Project Skyfire was over, and the vision of wildfire prevention by lightning suppression was largely forgotten.
3. The final frontier: Lightning protection in the Apollo era
While Project Skyfire sought to prevent lightning by modifying a cloud’s process of charge generation, the program briefly reviewed the prospect of alternative methods. In an early progress report (Barrows et al. 1954), the project team speculated, “If a good electrical conductor were placed vertically in a thunderstorm cloud, the charges being generated would presumably discharge through it and neutralize themselves to nondangerous values. Similarly, if the conductor went from Earth to the bottom charge center of a cloud, lightning to the ground would be eliminated. A wire would be an effective but impractical conductor for this job. Air ionized by radioactivity could conceivably offer some hope.” Although this idea of redistributing developing charges within the storm was never pursued during Project Skyfire, it would later appear again as the basis for a separate lightning suppression program.
In 1963, Drs. Heinz W. Kasemir and Helmut K. Weickmann of the U.S. Army Electronics Laboratory first described the use of metallic chaff as a cloud seeding agent for lightning suppression applications (Welckmann 1963; Kasemir and Weickmann 1965). Chaff is a common military radar countermeasure made up of hair-like strands of fiberglass coated in a thin layer of aluminum (Brandin et al. 1997). The low density of the fiberglass strand provides a lightweight material that will readily disperse through the airspace, while the thin aluminum coating creates the electromagnetic properties of a metallic material. When released from an aircraft, chaff fibers form a plume of highly reflective material that can remain suspended in the airspace for several hours. This airborne metallic plume can “confuse” radar-guided missile systems by providing an aircraft-like decoy signature to which incoming missiles are drawn. A widespread blanket of chaff can also be dispersed across a region of the airspace to produce a broad cloak of high radar reflectivity, which can obscure from radar surveillance any activities occurring within. Weickmann and Kasemir proposed that chaff fibers released at the base of a developing storm would be ingested within the central updraft and carried through the vertical depth of the storm structure. As an electric field begins to develop, corona discharge (i.e., St. Elmo’s fire) forms at the sharp ends of each aluminum chaff fiber, transforming electrically insulating air into an ionized plasma through which electrical current can flow. By continuously redistributing—and thereby neutralizing—charges within the storm in a weak electric field, the strong electric fields required to produce lightning would never develop (Kasemir and Weickmann 1965).
Preliminary field experiments were undertaken in the skies over Flagstaff, Arizona, in August 1966. An instrumented C-47 aircraft dispersed chaff under developing cumulus in a series of passes, continually recording the local electric field using two onboard electric field mills, as well as any presence of corona discharge on the ejected chaff fibers by a Litton Industries corona indicator. The experiment confirmed that corona formed on the 15-cm chaff fibers as electric fields reached 30 kV m−1, and that chaff released into a region of 300 kV m−1 completely eliminated the electric field within 10 min of seeding (Jones 1967; Kasemir 1973). As with many prior experiments of the Project Skyfire era, a relative lack of replicative samples and limited field trials prevented a clear evaluation of the approach; however, a resurgence of interest was soon to follow. On 14 November 1969, the Apollo 12 spacecraft was struck by lightning twice shortly after liftoff, resulting in instantaneous loss of inertial guidance, onboard telemetry, and electrical power generation and distribution systems (Merceret et al. 2010). The mission was saved by the quick thinking of the flight control team and decisive actions of the crew, but this averted disaster highlighted the risk lightning posed to spaceflight (Durrett 1976; Merceret et al. 2010). With the safety of future Apollo missions in question, interest in lightning suppression technology was renewed (Durrett 1976; Merceret et al. 2010).
The sudden need to protect spacecraft from lightning strike motivated the creation of Project Thunderbolt, an intensive set of experiments sponsored by NASA and NOAA to evaluate the use of chaff in mitigating lightning hazards (Rudosky 1972). Perhaps the most compelling demonstrations of lightning suppression came from the Project Thunderbolt field campaigns over Boulder, Colorado, during the summers of 1972 and 1973 (Holitza and Kasemir 1974; Kasemir et al. 1976). As in the Flagstaff experiments, an instrumented aircraft (B-26) released chaff under cumulus congestus clouds to determine the effect of seeding on electric field strength. Each seeding pass under a storm took approximately 1 min and released around 2 kg of chaff fibers—around 20 times more than would be necessary from theoretical calculations (Kasemir et al. 1976). Onboard electric field mills served the dual purpose of recording the local electric field strength and occurrence of lightning strikes, evidenced by a sudden discontinuity in the field strength (Kasemir et al. 1976). Prior to seeding, statistical analysis using a nonparametric Wilcoxon two-sample rank test indicated no significant difference in lightning activity between the seeded and control storms, suggesting the two samples of storms had similar initial electrical characteristics. Following chaff release, the Wilcoxon test indicated a significant decrease in lightning activity within seeded storms that was unlikely to be due to chance alone (Kasemir et al. 1976). Moreover, seeded storms demonstrated accelerated rates of electric field decay, which completely eliminated strong fields up to 50 times faster than the natural decay over the unseeded storm life cycle (Holitza and Kasemir 1974). In total, the study produced only 10 seeded and 18 control storms, and some concerns remained about the nonrandomized methods used to determine which storms should be seeded (Battan 1977). Nevertheless, the experiments demonstrated a likely effect of chaff on a storm’s ability to produce lightning, motivating the next stages of research toward an operational system for protecting rocket launches from lightning strike.
Extensions to the Boulder studies were made during the summer of 1974. In these operations, two NOAA T-29 aircraft made repeated penetration flights into thunderstorms at different altitudes, with one releasing chaff and the other measuring corona production using an onboard microwave radiometer (Rust and Krehbiel 1977). Flights within the cloud, rather than below cloud base, enabled a new perspective on the effects of chaff within the storm. This randomized experiment left little doubt that chaff seeding produced rapid onset of corona discharge that was sustained within the cloud beyond the termination of the seeding procedure (Rust and Krehbiel 1977). Within a small isolated thunderstorm that had been seeded with chaff, the electrical current produced by the collective chaff corona was estimated at 0.1 A, serving to decay the electric field within the storm (Rust and Krehbiel 1977).
As mounting experimental evidence linked chaff seeding to modification of storm electrical properties, NASA expressed interest in a field trial at Kennedy Space Center in conjunction with the Apollo-Soyuz Test Program. A nonrandomized experiment was conducted 16–27 July 1975 during which chaff was released into developing thunderstorms from a NOAA T-29 aircraft (Rust et al. 1977; Merceret et al. 2010). Supporting measurements were made from seven additional instrumented aircraft, including a NASA C-45, T-38, and Learjet, Naval Research Laboratory S2-D, New Mexico Institute of Mining and Technology Schweizer powered glider, and U.S. Air Force C-130 and RF-4C (Rust et al. 1977; Merceret et al. 2010). Although the experiment was not configured to produce statistically meaningful results, two important conclusions were drawn. First, the vertical structure of thunderstorms in Florida is far less conducive to seeding at cloud base than storms in the Western states (see Williams et al. 2005), possibly necessitating seeding within the cloud. Second, the multicellular structure of Florida storm systems would likely require distributed chaff releases—potentially by multiple coordinating aircraft—to effectively seed all lightning-producing updrafts within the system (Rust et al. 1977). The study presented several next steps for further developing the technique as an operational lightning suppression method at Kennedy Space Center during launches and reentries, but the 1975 experiment would ultimately be the last. Despite generally promising field results and the development of supporting analyses with a cloud model (Helsdon 1980), NASA cancelled the program due to concerns about the presence of chaff affecting radio communications between the spacecraft and ground control (Ruhnke 1971; Mazur and Ruhnke 2012). Although Kasemir would go on to conduct airborne electric field measurements during the 1976 Thunderstorm Research International Program at Kennedy Space Center, his proposed experiments on chaff seeding were dropped from the project (Pierce 1976; Dennis 1980, p. 220). Lightning suppression research was once again abandoned, and the responsibility for mitigating lightning hazards reverted to weather forecasters.
4. Looking back: Modern prospects and perspectives
It has been over 75 years since Schaefer first speculated on the use of glaciogenic cloud seeding to modify lightning production in storms (Schaefer 1949) and nearly 50 years since the final field experiment in lightning prevention by chaff seeding (Rust et al. 1977). It should be noted that we delineate these two efforts toward developing in situ suppression, modification, or outright prevention of lightning from other approaches that attempt to guide or trigger lightning strikes. For example, methods have been developed to trigger lightning to strike in “desirable” locations using rockets (e.g., Newman et al. 1967) or lasers (e.g., Houard et al. 2023), and other technologies for hardening infrastructure to lightning strikes are commonplace (Tobias 2004). In their design to prevent lightning, Project Skyfire and Project Thunderbolt were unique.
Retrospective evaluation of these two historical lightning suppression efforts is complicated by the fact that their failures were at least partially attributed to operational side effects. The glaciogenic seeding of Project Skyfire threatened to inadvertently redistribute rainfall in drought-stricken conditions, while chaff seeding at spacecraft launch sites by Project Thunderbolt posed a risk of interfering with local communication systems. Neither program was canceled strictly due to a lack of technical efficacy in modifying the frequency or characteristics of lightning strikes. Considering the technological advancements that have been made since these pioneering programs—particularly in atmospheric measurement technology, lightning observation platforms, and computational analysis techniques—it is interesting to consider what a modern evaluation of these approaches might reveal.
The utility of modern weather sensing infrastructure in investigating these topics was highlighted in the early 1990s, when combined observations from the U.S. National Lightning Detection Network (NDLN) and Next-Generation Weather Surveillance Radar Network (NEXRAD) revealed a potential case of inadvertent lightning suppression over Arizona (Maddox et al. 1997). The observational study speculated that chaff released by the U.S. Air Force during routine training exercises had the potential of modifying the electrical characteristics of nearby storms, which manifested as reduced lightning strike activity in regions downwind of military training ranges (Maddox et al. 1997). Although the role of military chaff releases in inadvertently affecting storm electrification was not pursued, recent upgrades in NEXRAD hardware have enabled routine radar detection and tracking of chaff plumes (Kurdzo et al. 2018). Coupled with new lightning mapping platforms [e.g., Geostationary Lightning Mapper (GLM); Goodman et al. 2013], these observations hold the potential for determining inadvertent effects of chaff on lightning density (Fig. 3), as well as providing an initial foothold toward a contemporary evaluation of lightning suppression in the applications for which it was originally envisaged.
Investigating the effect of chaff on thunderstorm electrification using serendipitous observations of military training exercises from weather observation systems. (left) Hybrid-scan radar reflectivity factor image from the Key West, Florida NEXRAD site (KBYX; yellow star), at 2208 UTC (1808 EDT) 29 Mar 2023. (right) The same NEXRAD radar image, now with military chaff plumes (grayscale) distinguished from weather signals, and GLM observations of lightning overlaid (red Xs). A storm developing in close proximity to a chaff plume is annotated by the black-yellow dashed oval and can serve as an opportunistic test bed for analyzing impacts of chaff on lightning density.
Citation: Bulletin of the American Meteorological Society 105, 11; 10.1175/BAMS-D-24-0109.1
Recent years have produced some of the largest and most devastating wildfires on record, directly contributing to loss of life, destruction of infrastructure, and environmental and ecological degradation, as well as producing far-reaching negative impacts on health and wellbeing from poor air quality (Burke et al. 2021). As anthropogenic environmental change continues to intensify global wildfire frequency, duration, and human exposure to these hazards (Jolly et al. 2015), there may be growing motivation to strategically prevent ignitions in high-risk situations. Unlike Project Skyfire’s broad-brush vision of forest fire prevention, modern application might view this approach as a “break glass in case of emergency” technology for circumstances when lives or critical infrastructure are at risk, or to inhibit new lightning ignitions when firefighting resources are already deployed at full capacity. In particular, there is evidence that wildfire smoke invigorates lightning production in nearby storms (Liu et al. 2021), which may result in compounding management pressure as ongoing burns directly increase new lightning ignition points. Targeted lightning suppression may prevent these new ignitions, temporarily alleviating strain on resources and personnel. In some respects, this management approach may eventually mirror that of prescribed burns—strategically initiating burns under ideal conditions to reduce fuel loads—by enabling the capability to schedule prescribed nonburns—strategically preventing lightning ignitions under hazardous conditions to buy time until other management approaches may be taken or additional resources may be deployed. As a path forward, the chaff-seeding methods developed during Project Thunderbolt could provide a technological solution for application to wildfire prevention, especially in remote regions where potential effects on communication systems could be minimized.
Similarly, lightning protection in space launch applications remains an unsolved problem. A catastrophic example of the risk lightning poses to spacecraft occurred on 26 March 1987 when an Atlas-Centaur launch vehicle was struck by lightning during takeoff from Cape Canaveral Space Force Station on the east coast of Florida (Christian et al. 1989). The triggered lightning strike resulted in electrical malfunction in the guidance control system, breakup of the vehicle, and total loss of the payload—a U.S. Navy communications satellite (Christian et al. 1989; Merceret et al. 2010). At present, the Lightning Launch Commit Criteria (LLCC), a checklist of meteorological conditions that must be satisfied prior to takeoff, is still the primary method of lightning risk mitigation (Merceret et al. 2010). In an effort to avoid operating in risky situations, the LLCC also represents the dominant source of launch delays and scrubs at NASA Kennedy Space Center and Cape Canaveral Space Force Station (Gardner et al. 2024). Almost 50 years have passed since concerns of chaff interference ended Project Thunderbolt at Kennedy Space Center, and communication systems have continued evolving since that time. With increasing demand for launch windows within a growing commercial space sector, reevaluation of lightning suppression technology in this application may be warranted.
Much has changed since the last time scientists attempted to disarm the thunderstorm. Sitting atop his lightning lookout tower in 1949, Schaefer would have struggled to anticipate a future in which lightning was observed at continental scales from space (e.g., Goodman et al. 2013). In 1972, while he bounced in the turbulent flights of a repurposed World War II bomber, Kasemir could have only dreamt of the uncrewed cloud seeding aircraft that exist today (e.g., Miller et al. 2024). Enormous potential now exists for the application of contemporary technology to the task of lightning suppression for mitigating loss of life, property, resources, and infrastructure. However, an equal—if not greater—emphasis must be placed on understanding the meteorological, environmental, ecological, and societal impacts of human intervention against natural disasters. Regardless of the ultimate outcome, the first step toward weighing the costs against benefits and balancing the risks against rewards will be increasing overall awareness of these historical lightning suppression studies and translating their vision into the modern-day context.
Acknowledgments.
Distribution Statement A: Approved for public release. Distribution is unlimited. This material is based upon work supported by the Department of the Air Force under Air Force Contract FA8702-15-D-0001. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Department of the Air Force. This work benefited from thoughtful discussions with Ken Cummins, Robert Maddox, and Dusan Zrnić.
Data availability statement.
The data used to produce Fig. 3 are publicly available from AWS Open Data Registry (GLM; https://registry.opendata.aws/noaa-goes/) and Google Cloud Storage (NEXRAD; https://console.cloud.google.com/marketplace/product/noaa-public/nexrad-l3).
References
Appleman, H. S., 1968: The operational dissipation of supercooled fog: Project Cold Cowl 1967–1968. United States Air Force, Air Weather Service Tech. Rep. 205, 16 pp., https://apps.dtic.mil/sti/tr/pdf/AD0668439.pdf.
Arnold, K., 1964: Project Skyfire lightning research. Proc. Third Tall Timbers Fire Ecology Conf., Tallahassee, FL, Tall Timbers Research, 121–130, https://www.frames.gov/catalog/30799.
Barrows, J. S., 1968: Preventing fire from the sky. USDA Yearbook of Agriculture, 90th Congress, 2nd Session, House, 217–223.
Barrows, J. S., V. J. Schaefer, and P. B. MacCready, 1954: Project Skyfire: A progress report on lightning fire and atmospheric research. Intermountain Forest and Range Experiment Station, USDA Forest Service Research Paper INT-35, 49 pp., https://search.worldcat.org/title/project-skyfire-a-progress-report-on-lightning-fire-and-atmospheric-research/oclc/39306233.
Battan, L. J., 1959: Cloud-physics research in the Soviet Union. Bull. Amer. Meteor. Soc., 40, 444–464, https://doi.org/10.1175/1520-0477-40.9.444.
Battan, L. J., 1967: Cloud seeding and cloud-to-ground lightning. J. Appl. Meteor., 6, 102–104, https://doi.org/10.1175/1520-0450(1967)006<0102:CSACTG>2.0.CO;2.
Battan, L. J., 1977: Comment on ‘Lightning suppression by chaff seeding at the base of thunderstorms’ by H. W. Kasemir, F. J. Holitza, W. E. Cobb, and W. D. Rust. J. Geophys. Res., 82, 1799, https://doi.org/10.1029/JC082i012p01799.
Baughman, R. G., D. M. Fuquay, and P. W. Mielke Jr., 1976: Statistical analyses of a randomized lightning modification experiment. J. Appl. Meteor., 15, 790–794, https://doi.org/10.1175/1520-0450(1976)015<0790:SAOARL>2.0.CO;2.
Blanchard, D. C., 1996: Serendipity, scientific discovery, and Project Cirrus: Walter Orr Roberts Lecture. Bull. Amer. Meteor. Soc., 6, 1279–1286.
Borland, S. W., and Coauthors, 1977: Hail suppression concepts and seeding methods. Hail: A Review of Hail Science and Hail Suppression, Amer. Meteor. Soc., 181–193.
Brandin, R., and Coauthors, 1997: Environmental effects of self-protection chaff and flares. Science Applications International Corp., Tech. Rep., 241 pp.
Burke, M., A. Driscoll, S. Heft-Neal, J. Xue, J. Burney, and M. Wara, 2021: The changing risk and burden of wildfire in the United States. Proc. Natl. Acad. Sci. USA, 118, e2011048118, https://doi.org/10.1073/pnas.2011048118.
Changnon, S. A., and W. H. Lambright, 1987: The rise and fall of federal weather modification policy. J. Wea. Modif., 1, 1–12.
Christian, H. J., V. Mazur, B. D. Fisher, L. H. Ruhnke, K. Crouch, and R. P. Perala, 1989: The Atlas/Centaur lightning strike incident. J. Geophys. Res., 94, 13 169–13 177, https://doi.org/10.1029/JD094iD11p13169.
Dennis, A. S., 1980: Weather Modification by Cloud Seeding. International Geophysics Series, Vol. 24, Academic Press, 267 pp.
Downie, C. S., and B. A. Silverman, 1959: Military applications of supercooled cloud and fog dissipation (Vol. 59, No. 635). Aerophysics Laboratory, Geophysics Research Directorate, Air Force Cambridge Research Center, Air Research and Development Command, United States Air Force, 54 pp., https://books.google.com/books?id=zT4NlGISFIkC&ots=gpRUSmQ4cY&dq=%22Military%20applications%20of%20supercooled%20cloud%20and%20fog%20dissipation%22&lr&pg=PP1#v=onepage&q=%22Military%20applications%20of%20supercooled%20cloud%20and%20fog%20dissipation%22&f=false.
Durrett, W. R., 1976: Lightning–Apollo to shuttle. The Space Congress Proc., Cocoa Beach, FL, Canaveral Council of Technical Societies, 1–7.
Elsom, D. M., 2015: Lightning: Nature and Culture. Reaktion Books, 240 pp.
Gardner, S., E. White, B. Langhals, T. McNamara, W. Roeder, and A. E. Thal Jr., 2024: A field-mill proxy climatology for the Lightning Launch Commit Criteria at Cape Canaveral Air Force Station and NASA Kennedy Space Center. arXiv, 2403.070161v1, https://doi.org/10.48550/arXiv.2403.07016.
Gentry, R. C., 1969: Project STORMFURY. Bull. Amer. Meteor. Soc., 50, 404–410, https://doi.org/10.1175/1520-0477-50.6.404.
Goodman, S. J., and Coauthors, 2013: The GOES-R Geostationary Lightning Mapper (GLM). Atmos. Res., 125–126, 34–49, https://doi.org/10.1016/j.atmosres.2013.01.006.
Havens, B. S., 1952: History of project cirrus. General Electric Research Laboratory Rep. RL-756, 122 pp., https://alachuacounty.us/Depts/epd/EPAC/General%20Electric%20History%20Of%20Project%20Cirrus%20July%201952%20ORIGINAL.pdf.
Helsdon, J. H., Jr., 1980: Chaff seeding effects in a dynamical-electrical cloud model. J. Appl. Meteor., 19, 1101–1125, https://doi.org/10.1175/1520-0450(1980)019<1101:CSEIAD>2.0.CO;2.
Holitza, F. J., and H. W. Kasemir, 1974: Accelerated decay of thunderstorm electric fields by chaff seeding. J. Geophys. Res., 79, 425–429, https://doi.org/10.1029/JC079i003p00425.
Houard, A., and Coauthors, 2023: Laser-guided lightning. Nat. Photonics, 17, 231–235, https://doi.org/10.1038/s41566-022-01139-z.
Imyanitov, I. M., 1957: Preliminary data on experiments in regulating the development and changes of electric conditions in strong convection clouds in the southern regions of the European U.S.S.R. and the Transcaucasus. Tr. Gl. Geofiz. Obs., 129, 33–58.
Jolly, W. M., M. A. Cochrane, P. H. Freeborn, Z. A. Holden, T. J. Brown, G. J. Williamson, and D. M. J. S. Bowman, 2015: Climate-induced variations in global wildfire danger from 1979 to 2013. Nat. Commun., 6, 7537, https://doi.org/10.1038/ncomms8537.
Jones, D. M. A., 1967: Program in atmospheric electricity and cloud modification, Flagstaff–1966. Atmospheric Sciences Laboratory, United States Army Electronic Command, Tech. Rep. ECOM-02376-F, 124 pp., https://www.isws.illinois.edu/pubdoc/CR/ISWSCR-90.pdf.
Kasemir, H. W., 1973: Lightning suppression by chaff seeding. Environmental Research Laboratories, NOAA Tech. Rep. ERL 284-APCL 30, 36 pp.
Kasemir, H. W., and H. K. Weickmann, 1965: Modification of the electric field of thunderstorms. Proc. Int. Conf. on Cloud Physics, Tokyo and Sapporo, International Association of Meteorology and Atmospheric Physics, https://www.wiley.com/en-us/Heinz-Wolfram+Kasemir%3A+His+Collected+Works-p-9780875907376.
Kasemir, H. W., F. J. Holitza, W. E. Cobb, and W. D. Rust, 1976: Lightning suppression by chaff seeding at the base of thunderstorms. J. Geophys. Res., 81, 1965–1970, https://doi.org/10.1029/JC081i012p01965.
Kocmond, W. C., and J. E. Jiusto, 1968: Investigation of warm fog properties and fog modification concepts. NASA Contractor Rep. CR-1071, 74 pp., https://ntrs.nasa.gov/api/citations/19680016344/downloads/19680016344.pdf.
Krider, E. P., 2004: Benjamin Franklin and the first lightning conductors. Proc. Int. Commission on History of Meteorology, Waterville, ME, International Commission on History of Meteorology, 1–13.
Kurdzo, J. M., E. R. Williams, D. J. Smalley, B. J. Bennett, D. C. Patterson, M. S. Veillette, and M. F. Donovan, 2018: Polarimetric observations of chaff using the WSR-88D network. J. Appl. Meteor. Climatol., 57, 1063–1081, https://doi.org/10.1175/JAMC-D-17-0191.1.
Latham, D., and E. R. Williams, 2001: Lightning and forest fires. Forest Fires, Academic Press, 375–418.
List, R., 2004: Weather modification—A scenario for the future. Bull. Amer. Meteor. Soc., 85, 51–64, https://doi.org/10.1175/BAMS-85-1-51.
Liu, Y., E. Williams, Z. Li, A. Guha, J. LaPierre, M. Stock, S. Heckman, Y. Zhang, and E. DiGangi, 2021: Lightning enhancement in moist convection with smoke‐laden air advected from Australian wildfires. Geophys. Res. Lett., 11, e2020GL092355, https://doi.org/10.1029/2020GL092355.
MacCready, P. B., 1959: The lightning mechanism and its relation to natural and artificial freezing nuclei. Recent Advances in Atmospheric Electricity, Pergamon Press, 369–381.
MacCready, P. B., V. J. Schaefer, J. H. Dieterich, and J. S. Barrows, 1955: Project Skyfire: Cloud and Lightning Observation Handbook. Intermountain Forest and Range Experiment Station, USDA Forest Service Miscellaneous Publication No. 5, 55 pp., https://digital.archives.caltech.edu/collections/MacCreadyPB/MacCreadyPB_04_01_001_17/.
Maddox, R. A., K. W. Howard, and C. L. Dempsey, 1997: Intense convective storms with little or no lightning over central Arizona: A case of inadvertent weather modification? J. Appl. Meteor., 36, 302–314, https://doi.org/10.1175/1520-0450(1997)036<0302:ICSWLO>2.0.CO;2.
Mazur, V., and L. H. Ruhnke, 2012: Heinz-Wolfram Kasemir: His Collected Works. Amer. Geophys. Union, GeoPress, 718 pp.
Merceret, F. J., and Coauthors, 2010: A history of the lightning launch commit criteria and the lightning advisory panel for America’s space program. NASA/SP-2010-216283, 234 pp.
Miller, A. J., and Coauthors, 2024: Two new multirotor uncrewed aerial vehicles (UAVs) for glaciogenic cloud seeding and aerosol measurements within the CLOUDLAB project. Atmos. Meas. Tech., 17, 601–625, https://doi.org/10.5194/amt-17-601-2024.
Newman, M. M., J. R. Stahmann, J. D. Robb, E. A. Lewis, S. G. Martin, and S. V. Zinn, 1967: Triggered lightning strokes at very close range. J. Geophys. Res., 72, 4761–4764, https://doi.org/10.1029/JZ072i018p04761.
Orville, H. T., 1958: Final report of the Advisory Committee on Weather Control: Importance of weather and its modification. Bull. Amer. Meteor. Soc., 11, 583–598.
Pierce, E. T., 1976: The Thunderstorm Research International Program (TRIP)—1976. Bull. Amer. Meteor. Soc., 57, 1214–1216, https://doi.org/10.1175/1520-0477(1976)057<1214:TTRIP>2.0.CO;2.
Rudosky, J. C., 1972: Disarming the thunderstorm. NOAA, 2, 14–15.
Ruhnke, L. H., 1971: Atmospheric electricity problems at Kennedy Space Center. Proc. Eighth Space Conf., Session 3, Cocoa Beach, FL, Canaveral Council of Technical Societies, 11–12.
Rust, W. D., and P. R. Krehbiel, 1977: Microwave radiometric detection of corona from chaff within thunderstorms. J. Geophys. Res., 82, 3945–3950, https://doi.org/10.1029/JC082i027p03945.
Rust, W. D., F. J. Holitza, and W. E. Cobb, 1977: Preliminary test program in chaff dispersal within thunderstorms at Kennedy Space Center. NOAA Tech. Memo. ERL APCL-20, 17 pp., https://repository.library.noaa.gov/view/noaa/21211/noaa_21211_DS1.pdf.
Schaefer, V. J., 1946: The production of ice crystals in a cloud of supercooled water droplets. Science, 104, 457–459, https://doi.org/10.1126/science.104.2707.457.
Schaefer, V. J., 1948: The natural and artificial formation of snow in the atmosphere. Eos, Trans. Amer. Geophys. Union, 4, 492–498.
Schaefer, V. J., 1949: The possibilities of modifying lightning storms in the Northern Rockies. USDA Forest Service Station Paper No. 19, 23 pp., https://www.fs.usda.gov/rm/pubs_exp_for/priest_river/exp_for_priest_river_1949_schaefer.pdf.
Schaefer, V. J., 1955: Jet streams, thunderstorms, and Project Skyfire. Arch. Meteor. Geophys. Bioklimatol., 8A, 265–282, https://doi.org/10.1007/BF02247286.
Schaefer, V. J., 1977: An early account of a flight to modify lightning storms. J. Wea. Modif., 1, 1–7.
Silverman, B., 1976: Project Skywater. J. Wea. Modif., 2, 107–120.
Smith, D. M., 2017: Sustainability and wildland fire: The origins of Forest Service wildland fire research. USDA Forest Service FS-1085, 128 pp., https://www.fs.usda.gov/rm/pubs_series/wo/wo_fs1085.pdf.
Tobias, J. M., 2004: The basis of conventional lightning protection systems. IEEE Trans. Ind. Appl., 40, 958–962, https://doi.org/10.1109/TIA.2004.831277.
Vonnegut, B., 1947: The nucleation of ice formation by silver iodide. J. Appl. Phys., 18, 593–595, https://doi.org/10.1063/1.1697813.
Welckmann, H. K., 1963: A realistic appraisal of weather control. Z. Angew. Math. Phys., 14, 528–543, https://doi.org/10.1007/BF01601260.
Williams, E., V. Mushtak, D. Rosenfeld, S. Goodman, and D. Boccippio, 2005: Thermodynamic conditions favorable to superlative thunderstorm updraft, mixed phase microphysics and lightning flash rate. Atmos. Res., 76, 288–306, https://doi.org/10.1016/j.atmosres.2004.11.009.
Willoughby, H. E., D. P. Jorgensen, R. A. Black, and S. L. Rosenthal, 1985: Project Stormfury: A scientific chronicle 1962–1983. Bull. Amer. Meteor. Soc., 66, 505–514, https://doi.org/10.1175/1520-0477(1985)066<0505:PSASC>2.0.CO;2.
