Rain

by Cynthia Barnett

  On November 13, 1946, Schaefer rented an airplane, flew into a cold cloud over Mount Greylock in the nearby Berkshires, and dropped six pounds of dry ice pellets inside. The cloud “almost exploded” with ice crystals, Schaefer wrote in his notebook. Snow burst forth over the three-mile path of seeding. Langmuir, fifty miles away in the airport control tower, watched long, white streamers fall from the base of the cloud.

  GE lost no time in asking the military for access to a better airplane that could fly into higher clouds—and in releasing the news to the world. The New York Times crowed the next day that “numerous practical applications were expected to result from the project, including storage of moisture in the winter for spring irrigation and water power programs, steering heavy snowfalls away from city areas, and providing snow for winter resorts.” The Times quoted Langmuir as saying a pellet of dry ice the size of a pea could create enough nuclei for “several tons of snow” and “in a five-hour flight a single plane could generate hundreds of millions of tons of snow over a large area.”

  Letters, telegrams, and postcards poured in to GE and its scientists, full of ideas for commercial applications and those for public good. Movie producers wanted made-to-order blizzards. A search-and-rescue operation on Mount Rainier wanted to be able to clear clouds to spot downed aircraft. The Kansas State Chamber of Commerce wrote to President Harry Truman, asking the federal government to use GE’s technology to combat drought. The ever-cautious U.S. Weather Bureau replied. Chief Francis Reichelderfer wrote that it was impossible to know how much precipitation had been coaxed and how much was natural. Besides, seeding worked only in special circumstances, and drought wasn’t one of them. You cannot seed clouds in cloudless skies.

  —

  The next news flurries out of GE came in January 1947, after Bernard Vonnegut discovered that molecules of the compound silver iodide could also serve as artificial nuclei and “fool” cloud water droplets into crystallizing. Vonnegut experimented with shooting silver iodide from a generator on the summit of Mount Washington and “caused quite a nice snow squall downwind.” The GE News Bureau made a considerable leap: Pumping silver iodide into huge masses of air, “it might be possible to alter the nature of the general cloud formation over the northern part of the United States during winter,” the company declared in a press release. “It would prevent all ice storms, all storms of freezing rain, and icing conditions in clouds…. It should be possible to change the average temperature of some regions during winter months.”

  As the company’s PR flacks and Langmuir touted large-scale weather control, another arm of GE tried to stop the bragging and even quash the research. The corporation’s lawyers saw enormous risk in property damage and personal injury lawsuits. Manufactured snow and rain would lead, as surely as natural precipitation, to traffic accidents, injurious falls, floods, and who knows what unimagined mishaps. Plaintiffs couldn’t sue over an act of God. They certainly would over an act of GE.

  In February 1947, corporate bosses informed Langmuir’s team that the company would transfer all cloud-seeding experimentation to the military. In what was later named Project Cirrus, the U.S. Army Signal Corps, Office of Naval Research, Air Force, and GE researched “cloud particles and cloud modifications.” The contract was explicit that “the entire flight program shall be conducted by the government, using exclusively government personnel and equipment, and shall be under the exclusive control of such personnel.” GE employees were restricted to laboratory work and reports.

  Between 1947 and 1952, Project Cirrus conducted about 250 cloud experiments, from seeding to fire suppression. While the results of a few cloud-seeding runs were spectacular, trials in the clouds over Ohio in 1948 and California and the Gulf states in 1949 led researchers to conclude that seeding could neither initiate storms nor relieve drought. The best it could do was squeeze a little more precipitation from clouds that were going to rain or snow anyway. But Langmuir continued to see promise of pluviul proportions. After he credited seeding in New Mexico with a band of heavy rainfall across the United States, even some fellow scientists thought the Nobel Prize winner had lost his objectivity—or simply never understood the complexity of the atmosphere as well as he had his own field of chemistry. “No chemist, physicist, or mathematician who has not lived with and learned to understand this peculiar nature of meteorology can pass valid judgment on how the atmosphere will react if one interferes with the details of the natural processes,” wrote the eminent meteorologist Sverre Petterssen in his memoirs as he pondered his work with Langmuir on cloud-seeding. “Moreover, to determine whether or not the atmosphere has responded to outside interference, it is necessary to predict what would have happened had it been left alone.” From Robert St. George Dyrenforth to Irving Langmuir, that was always the rub: How could anyone be sure whether the clouds would have rained without the prompt?

  —

  While civilian scientists researched cloud-seeding as a way to combat drought in the arid West, hail on the plains, and hurricanes in the East, military strategists were chasing a darker, secret dream: weather as a weapon of war. In 1947, General George C. Kennedy, commander of the U.S. Strategic Air Command, declared, “The nation which first learns to plot the paths of air masses accurately and learns to control the time and place of precipitation will dominate the globe.” Ten years later, an advisory committee reported to President Dwight Eisenhower that weather control could become a “more important weapon than the atomic bomb.”

  The U.S. military made its first large-scale attempt to unleash rain as a weapon during the Vietnam War. Beginning with trials in 1966, and continuing every rainy season until July 1972, “Project Popeye” dropped nearly fifty thousand loads of silver iodide or lead iodide in the clouds over Vietnam, Laos, and Cambodia to induce heavy rains. The idea was to flood out roads, cause landslides, and make transportation as difficult as possible well beyond monsoon season—essentially, to keep the Ho Chi Minh Trail a muddy mess and foil North Vietnam’s ability to move supplies and personnel.

  Operating out of Udorn Royal Air Base in Thailand without knowledge of the governments of Thailand, Laos, or South Vietnam, the Fifty-Fourth Weather Reconnaissance Squadron flew 2,600 sorties that dispersed 47,409 cloud-seeding flares—a payload code-named “Olive Oil”—to make rain over the trail.

  In 1971, the nationally syndicated columnist Jack Anderson broke a story about the secret rain soldiers in the Washington Post. In 1972, Seymour Hersh detailed the mission and the name “Project Popeye,” revealed in the Pentagon Papers. The squadron dropped its last cloud-seeding flare a few days later. At congressional hearings convened by Senator Claiborne Pell of Rhode Island, the Nixon administration and military officials refused to admit the rain runs as they opposed Pell’s resolution for a treaty to ban “any environmental or geophysical modification activity as a weapon of war.”

  The hearings revealed a great reluctance among many Americans to proceed with weather warfare. At the University of California at Los Angeles, the climatologist Gordon J. F. MacDonald warned that if rain could become a secret weapon, so too could floods, tidal waves, and droughts: “Such a ‘secret war’ need never be declared or even known by the affected population,” MacDonald said. “It would go on for years with only the security forces involved being aware of it. The years of drought and storm would be attributed to unkindly nature and only after a nation was thoroughly drained would an armed takeover be attempted.”

  The House and Senate ultimately adopted anti-weather-warfare resolutions. In 1977, the United States, the Soviet Union, and other nations ratified a UN treaty prohibiting military “or any other hostile use” of environmental-modification techniques.

  The results of Project Popeye have never been clear. Military scientists estimated rainfall increased between 15 and 30 percent over the Ho Chi Minh Trail. But was it the Weather Squadron’s chemicals, or capricious monsoons? Project Popeye’s final report claims “that judicious seeding of properly selected clouds re
sulted in remarkably increased cloud growth relative to the growth that would have occurred naturally.” Today, leading atmospheric scientists as well as the intrepid private meteorologists who make their living seeding clouds say that would have been utterly impossible to know four decades ago. Even today, it is not entirely knowable.

  —

  One winter morning in Utah under bluebird skies with white-feather clouds, I drove south of Salt Lake City to the oldest commercial weather-modification company in the United States. North American Weather Consultants is tucked into a suburban office park behind a ballet studio and a chiropractor. The firm was founded in Southern California in 1950, part of an enthusiastic trend of private meteorology entrepreneurs who set up shop from the western United States to Australia in the wake of GE’s cloud-seeding breakthroughs.

  In the office, satellite cloud images swirl across large-screen televisions and a wooden cross hangs on the wall. The company’s president, Don Griffith, and vice president Mark Solak are gray-haired meteorologists with soft arms in short-sleeved dress shirts. They are not men who could scramble up and down a rain derrick like Charles Hatfield. But like him, they stress humility in the cloud wizardry they perform for hydropower plants, ski resorts, and drought-ridden state and local governments.

  Griffith has blown silver iodide into winter clouds over Utah’s mountains for four decades to increase snowpack—and the annual runoff to rivers and reservoirs. North American Weather Consultants has about 150 ground-based generators set up in valleys and foothills on Utah’s national forestlands. The devices look like tall space heaters arranged to warm the elk and snowshoe hares. When the meteorologists detect a winter storm with supercooled water droplets and optimal wind speeds for dispersing ersatz nuclei, they light the propane flames, which slowly burn the silver iodide into furling ribbons that seed the storm.

  State water scientists in Utah estimate these efforts have increased the water stored in snow an average 13 percent annually, adding about 250,000 acre-feet a year to reservoirs and aquifers. But seeding remains controversial among many meteorologists, for both the results touted and the uncertainty of its influence on a system so dynamic, the father of chaos theory, Edward Lorenz, suggested it might be influenced by the flap of butterfly wings.

  Indeed, after the unbridled excitement over GE’s front-page headlines in the 1940s, the next half century of weather modification was something of a letdown for meteorologists like Griffith and Solak who entered the field during a time of high interest and public investment. In the mid-1970s, the federal government was spending about $20 million a year on weather-modification research. But in the next couple of decades, that dwindled to nearly nothing. The chaotic nature of rain and snow, and scientists’ inability to measure induced versus natural precipitation, meant the seeders could never definitively prove their results. It did not help that many of their rainmaking ancestors had been charlatans, their scientific forefathers exaggerators. A 2003 report from the National Research Council of the National Academies concluded: “There is still no convincing scientific proof of the efficacy of intentional weather-modification efforts.”

  Nine states have proof enough. As drought spreads and population grows in the arid West, cloud-seeding is one strategy among many balanced by water managers trying to keep reservoirs flowing. Since seeding is among the cheapest—a few dollars an acre-foot, compared with a few hundred dollars an acre-foot for reservoir storage or interbasin transfers, or a few thousand for seawater desalination—water managers see it as a small price to pay. Utah, California, Nevada, Idaho, Wyoming, Colorado, North Dakota, Kansas, and Texas all engineer clouds, as do many local governments, agricultural consortiums, and other rain-dependent businesses. A couple of hydroelectric companies in the United States and Australia have seeded clouds for more than fifty years without interruption.

  Elsewhere, many foreign governments reached out to the clouds as the U.S. government stepped back from the science it helped invent. More than forty countries have active weather-modification projects, including Thailand, where the king himself—His Majesty King Bhumibol Adulyadej—holds a patent for “weather modification by royal rainmaking technology.” Indonesia’s disaster-mitigation agency has begun seeding monsoon storms over the Java Sea to try to make them rain before they hit Jakarta, where annual monsoon flooding can paralyze life and cause millions of dollars in damage.

  China spends by far the most of any government on both actual seeding and research, with 47,700 employees on its weather-modification payroll, along with fifty cloud-seeding jets, 7,034 rocket launchers, and 6,902 mortars that look like Robert St. George Dyrenforth’s wildest dreams come true. China claims that 560,000 cloud-seeding missions in the past ten years helped release nearly 500 billion tons of rain, or twelve times the water-storage capacity of the Three Gorges Dam, which spans the Yangtze River.

  Roelof Bruintjes, lead scientist for weather modification at the National Center for Atmospheric Research in Boulder, Colorado, who also heads an expert team for the World Meteorological Organization, is skeptical of China’s claims. But he says new models and technologies are tantalizingly close to clarifying the impacts of seeding. On a pair of mountain ranges in southern Wyoming, atmospheric scientists from the University of Wyoming, the National Center for Atmospheric Research, and the University of Colorado are wrapping up the most comprehensive seeding study in recent decades, including a blind statistical analysis of 150 seeding events over seven years.

  Results were still nearly a year off when I talked to the lead researcher, a University of Wyoming professor named Bart Geerts. He told me the compounded evidence points to a general increase in precipitation on the seeded ranges; increases in the order of 10 to 15 percent could be attributed to seeding rather than to chance. But the study will not answer the other big question that has always followed the cloud-seeding industry: By taking a bit more rain and snow from the clouds, aren’t they keeping it from the place where it would have fallen naturally?

  Griffith of North American Weather Consultants characterizes the “robbing Peter of rainfall to water Paul” worry as a misconception; industry studies have shown that areas fifty to a hundred miles downwind from the seeding target also reap the benefits of increased precipitation. But Geerts told me the issue is much more complex in a global system where each rain or snow fall decreases the amount of water vapor downwind as it travels to the next mountain range and the next. Amid the mysterious workings of Earth and its atmosphere, one thing is clear—when we change one part of the rain cycle, we change another somewhere else.

  —

  In October 1947, the eighth tropical storm of the season spun out of the Caribbean, clipped western Cuba, and strengthened into a hurricane as it made landfall at Cape Sable in the Everglades, bringing spectacular thunderstorms and heavy rains to the southern tip of Florida. The deluges left two thousand people homeless in Dade County. Miamians rowed through the streets in skiffs and rafts to check on friends and tour the flooded city.

  After speeding out of Florida and into the Atlantic Ocean, the Cape Sable Hurricane stalled 350 miles offshore from the Florida-Georgia border. Forecasters expected it to head farther out to sea. The GE and military scientists working on Project Cirrus decided it was a good time to try what the New York Times called their “daring meteorological experiment…to determine whether or not the colossal vortex that we call a hurricane can be broken by making it precipitate the thousands of tons of water that it contains.”

  On October 13, 1947, three Project Cirrus aircraft left MacDill Air Force Base in Tampa at 8:20 a.m. and arrived at the outer wall of the hurricane’s eye a little before 11:00. Lieutenant Commander Daniel Rex of the navy observed an unusual, “exceedingly active squall line” of cumulonimbus clouds with tops boiling 60,000 feet in the sky, extending out from the center of the storm to the southeast. Rex decided to seed over a cloud shelf along the southwest side of the storm, dropping eighty pounds of dry ice, then an additional fifty pounds
each into two convective towers. He described a “pronounced modification” of the seeded area, with overcast clouds turning to scattered snow clouds over three hundred square miles. For a day or so, forecasters were not sure what the hurricane would do. The evening of October 14, it turned back toward land.

  The storm barreled into the southern Georgia coastline on the morning of October 15 at what’s now called Tybee Island. Fishing trawlers sank and phone service was lost. Thousands of Savannah residents evacuated to churches and schools. “Savannah early this morning was hurriedly throwing up storm protections as the erratic Atlantic disturbance was moving almost directly toward the city,” the local newspaper reported.

  Still, Georgia averted major disaster and the U.S. mail was not interrupted, bearing out the sentiment chiseled in gray stone over the New York Post Office on Eighth Avenue: “Neither rain, nor sleet, nor gloom of night stays these couriers from the swift completion of their appointed rounds.”*

  Always on the side of big weather control, GE’s Langmuir was certain that the seeding had changed the storm’s direction and sent it toward Georgia. The federal government’s chief hurricane forecaster in Miami, Grady Norton, believed it, too. But the Weather Bureau’s official and final take, issued from Washington, was that the hurricane had already begun to change direction at the time of the seeding, and that a ridge of high pressure, not dry ice, turned the storm.

  Soon after the fateful hurricane, GE announced it would no longer enforce its weather-modification patents. By putting them in the public domain, the company could be released from legal liability should its work be used to change the weather in some undesirable way.

  Hurricane scientists were dismayed that the “unbelievably casual” seeding of the Cape Sable storm set back their modification research many, many years. Interest did not surge again for half a century, after Hurricane Katrina. In 2009, the billionaire Microsoft founder, Bill Gates, through the Seattle-based tech investment firm Intellectual Ventures, filed for patents with a handful of scientists working on technologies to weaken hurricanes—still chasing humanity’s age-old dream to control the rain.