Project Stormfury AKA Controlling Hurricanes
Project Stormfury was an attempt to weaken tropical cyclones by flying aircraft into them and seeding with silver iodide. The project was run by the United States Government from 1962 to 1983. Project Stormfury AKA Controlling Hurricanes
When the U.S. Tried to Control Hurricanes
From the 1940s to the 1970s, Project Stormfury and other government efforts tested the limits of the power of science.
As the end of the 2019 Atlantic hurricane season approaches on Nov. 30, the tally of destruction left by storms this year has been enormous. In August, Hurricane Dorian lingered over much of the Bahamas for three devastating days, leaving the country with over 65 people dead. In September, Tropical Storm Imelda dropped 40 inches of rain on coastal Texas. Repairing the damage caused by both storms will cost many billions of dollars.
Given the destruction and loss of life caused by such storms, the idea of diverting them is tempting. This summer, President Trump reportedly asked senior officials to explore using nuclear weapons to divert hurricanes from the U.S. This notion is so popular that the website of the National Oceanic and Atmospheric Administration (NOAA) includes a helpful explainer on the many reasons it is not a good idea (think radioactive fallout).
Trying to direct the course of a massive hurricane may sound foolhardy, but the idea was once pursued with serious intent. In the wake of World War II, many believed that control of the weather was imminently possible and would be a boon, making it possible to divert damaging storms and deliver rainfall to drought-stricken communities.
Cloud seeding, the basic tool for modifying clouds and therefore hurricanes, was first developed in 1946 by researchers at General Electric, who noticed that dry ice caused the clouds created by their own breath to produce snow inside the company’s new domestic freezers. The dry ice acted as an artificial nucleus, encouraging super-cooled water to form crystals of snow and in the process release latent heat.
That technique—modified to use tinier and more effective crystals of silver iodide—was soon put to use in real clouds to see if rain could be produced. Results were mixed, but projects in small-scale weather control nevertheless continued, with enthusiasm high in arid Western states.
Almost immediately interest ran from individual clouds to entire hurricanes. By October 1947, scientists working on the government-funded Project Cirrus made the first attempt to modify a hurricane. The results were both alarming and inconclusive. After seeding, the hurricane, east of Jacksonville, Fla., abruptly altered its course, reversing track and heading west before making landfall on the coast of Georgia and South Carolina and causing a public outcry. It was impossible to know for sure whether the seeding had caused the change in direction, but the episode nevertheless cast a pall over the prospects of weather control.
Despite the risks, the allure of controlling one of the most destructive natural forces on earth remained strong. Following a series of devastating hurricanes in 1954 and 1955, Congress allocated funding for a National Hurricane Research Project tasked with both basic research and investigating storm modification. Promising results from a test made on Hurricane Esther in 1961 paved the way for a joint effort of the Navy and the U.S. Weather Bureau called Project Stormfury.
Researchers working on the project believed that the eyewall of a hurricane contained abundant supercooled water. Dropping enough silver iodide into this precise location in a storm, they theorized, could cause the eyewall to release enough latent heat that it would become unstable and move outward. Due to the conservation of angular momentum, this movement would cause the storm to slow and weaken, just as the widely outstretched arms of a spinning ice skater slow her down.
“This was absolutely mainstream science at the time,” says Hugh Willoughby, a professor of atmospheric science at Florida International University and a former director of NOAA’s Hurricane Research Division. It was based, Dr. Willoughby says, on the prevailing assumption that hurricanes were inherently unstable, “like something that’s balanced on the edge of a counter and if a cat bumps against it, it falls and breaks.” Given the right trigger, even a small amount of energy could be enough to perturb the storm into a weaker state.
It was decided to attempt to modify hurricanes only in a safe zone far enough from coastal regions that inadvertent landfall would be avoided. In 1963, the Stormfury team decided to carry out two modification attempts on Hurricane Beulah, even though the storm was relatively weak and had an indistinct eye. On the first attempt, the seeding material missed the giant clouds, and the storm remained unchanged. On the second, the seeding was on target and maximum winds declined by 20%.
A lack of suitable hurricanes for seeding frustrated further attempts to refine or ratify the hypothesis until 1969, by which time researchers had revised their understanding of the storms. Rather than trying to cause instability in the inner eyewall, they focused on injecting a massive amount of silver iodide to stimulate the formation of a second, outer rainwall that would weaken the original eyewall by cutting off its supply of heat and moisture.
They tested this hypothesis on Hurricane Debbie in 1969, dropping more than 1,000 silver iodide capsules into the storm. The hurricane seemed to respond, with a reduction of wind speed in line with that predicted by the hypothesis. The only other hurricane to be seeded under the program was Ginger in 1971, but the storm lacked a strong center, and the results were considered inconclusive.
As it turned out, Hurricane Debbie was to be the high point of Project Stormfury. The program stalled during the 1970s thanks to a combination of factors including a dearth of hurricanes in the target area. Following the revelation in 1972 that the U.S. military had been using cloud seeding to trigger rainfall in North Vietnam, weather control took on a newly sinister aspect. Research into hurricanes continued, however, and scientists made two important observations: Supercooled water was not as abundant in the storms as had been thought, and concentric eyewalls frequently occur naturally.
These two observations undermined the hypothesis on which modification attempts had been made. Since “Mother Nature has her own eyewall replacement cycle,” explains Ed Zipser, a professor of atmospheric science at the University of Utah, there’s not much point in trying to create an artificial one. The apparent successes of the past might have been a result of mere chance rather than seeding. When Project Stormfury was eventually cancelled in 1983, it was deemed a failure.
Today, no one is seriously pursuing the once-irresistible idea of modifying hurricanes. In addition to other problems with the Stormfury hypothesis, it is no longer assumed that reducing the intensity, or wind speed, of a hurricane would be beneficial. Since rainfall or storm surge and not winds cause the most damage, it’s unclear, says Dr. Zipser, “how much good you are doing by turning a small compact intense storm into a larger but weaker storm.” Hurricane Maria in Puerto Rico is a good example, says Dr. Zipser. “It wasn’t only the eyewall that destroyed the infrastructure of that island.”
It’s possible that new ideas for modifying storms will be developed in the future. What’s needed, says Dr. Willoughby, is a deeper understanding of the small-scale dynamics of cloud physics. As important as computer models are for pushing understanding forward, there’s no substitute for observations of real clouds. There is still much to learn from the terrifying fury of hurricanes.
The hypothesis was that the silver iodide would cause supercooled water in the storm to freeze, disrupting the inner structure of the hurricane, and this led to seeding several Atlantic hurricanes. However, it was later shown that this hypothesis was incorrect. It was determined that most hurricanes do not contain enough supercooled water for cloud seeding to be effective. Additionally, researchers found that unseeded hurricanes often undergo the same structural changes that were expected from seeded hurricanes. This finding called Stormfury’s successes into question, as the changes reported now had a natural explanation.
The last experimental flight was flown in 1971, due to a lack of candidate storms and a changeover in NOAA’s fleet. Project Stormfury was officially canceled more than a decade after the last modification experiment. Project Stormfury failed to reach its goal of reducing the destructiveness of hurricanes, but it was not without merit. The project’s observational data and storm lifecycle research helped improve meteorologists’ ability to forecast the movement and intensity of hurricanes.
Cloud seeding was first attempted by Vincent Schaefer and Irving Langmuir. After witnessing the artificial creation of ice crystals, Langmuir became an enthusiastic proponent of weather modification. Schaefer found that when he dumped crushed dry ice into a cloud, precipitation in the form of snow resulted.
With regard to hurricanes, it was hypothesized that by seeding the area around the eyewall with silver iodide, latent heat would be released. This would promote the formation of a new eyewall. As this new eyewall was larger than the old eyewall, the winds of the tropical cyclone would be weaker due to a reduced pressure gradient. Even a small reduction in the speed of a hurricane’s winds would be beneficial: since the damage potential of a hurricane increased as the square of the wind speed, a slight lowering of wind speed would have a large reduction in destructiveness.
Due to Langmuir’s efforts, and the research of Schaefer at General Electric, the concept of using cloud seeding to weaken hurricanes gathered momentum. Indeed, Schaefer had caused a major snowstorm on December 20, 1946 by seeding a cloud. This caused GE to drop out for legal reasons. Schaefer and Langmuir assisted the U.S. military as advisors for Project Cirrus, the first large study of cloud physics and weather modification. Its most important goal was to try to weaken hurricanes.
Robert Simpson became its first director, serving in this capacity until 1965. There were several guidelines used in selecting which storms to seed. The hurricane had to have a less than 10 percent chance of approaching inhabited land within a day; it had to be within range of the seeding aircraft; and it had to be a fairly intense storm with a well-formed eye. The primary effect of these criteria was to make possible seeding targets extremely rare.
No suitable storms formed in the 1962 season. Next year, Stormfury began by conducting experiments on cumulus clouds. From August 17 to 20 of that year, experiments were conducted in 11 clouds, of which six were seeded and five were controls. In five of the six seeded clouds, changes consistent with the working hypothesis were observed.
On August 23, 1963, Hurricane Beulah was the site of the next seeding attempt. It had an indistinct eyewall. In addition, mistakes were made, as the seedings of silver iodide were dropped in the wrong places. As a consequence, nothing happened. The next day, another attempt was made, and the seeders hit their targets. The eyewall was observed to fall apart and be replaced by another eyewall with a larger radius.The sustained winds also fell by twenty percent. All in all, the results of the experiments on Beulah were “encouraging but inconclusive.”
In the six years after Beulah, no seedings were conducted for several different reasons. In 1964, measurement and observation equipment was not ready to be used.The year after that, all flights were used for additional experimentation in non-hurricane clouds.
Joanne Simpson became its director beginning in 1965. While out to sea in August of the 1965 Atlantic hurricane season, Stormfury meteorologists decided that Hurricane Betsy was a good candidate for seeding. However, the storm immediately swung towards land, and on September 1, the planned flights were canceled. For some reason, the press was not notified that there were no seedings, and several newspapers reported that it had begun. As Betsy passed close to the Bahamas and smashed into southern Florida, the public and Congress thought that seeding was underway and blamed Stormfury. It took two months for Stormfury officials to convince Congress that Betsy was not seeded, and the project was allowed to continue. A second candidate, Hurricane Elena, stayed too far out to sea.
After Betsy, two other hurricanes came close to being seeded. Hurricane Faith was considered a likely candidate, but it stayed out of range of the seeding planes. That same year, recon flights were conducted into Hurricane Inez, but there were no seedings. Both the 1967 and 1968 seasons were inactive. Because of that, there were no suitable seeding targets in either of those two seasons.