Changing the weather has been a scientific quest since the 16th century, when rogue intellectual Leonardo da Vinci asked the city fathers of Verona to shoot cannonballs skyward to halt the hail. But it wasn’t until after World War II, at the improbable site of the General Electric Laboratory in Schenectady, New York, that a plan went into effect. In the beginning, a team that included atmospheric scientist Bernard Vonnegut (brother of novelist Kurt) sent up a plane and released dry ice into clouds on four days during November and December 1946. Whether by coincidence or through actual impact, the last day of seeding saw the heaviest snowfall of the winter around Schenectady. Vonnegut went on to invent what amounted to a nucleating machine: He dissolved silver iodide in acetone, sprayed the solution through a nozzle to make droplets, and then literally burned the droplets, producing trillions of nuclei; under the right conditions, each could form the core of a drop of water or flake of snow. But General Electric, wary of potential lawsuits, gradually moved away from direct involvement in weather research.
By the 1960s the U.S. military had taken the reins. Its effort, called Project StormFury, aimed to weaken hurricanes by seeding their upper reaches with silver iodide crystals, nucleating agents that would increase the amount of ice swirling around in the storm. The idea was that as water became ice, it would release heat. The heat, in turn, would widen the eye of the storm and decrease the strength of its winds.
Unfortunately, StormFury’s statistical findings were ambiguous. While human manipulations did sometimes seem to weaken hurricanes, test flights into the storms never provided proof. “What we didn’t know at the time,” says Charles Hosler, professor emeritus of meteorology at Penn State University and former StormFury panel chairman, “is that measuring the forces inside hurricanes is far more complex than what was possible with the equipment of the time.”
Neither fog, nor rain, nor hail
The shuttering of StormFury in 1983 signaled a new age of skepticism and the end of major federal funding for weather-control research. Indeed, while many practitioners pointed to statistical evidence suggesting their techniques worked, it was usually impossible to prove it; one could never precisely predict what would have happened had the intervention not taken place. Amid such doubt, the federal government backed off, and weather modification became the province of private companies and local municipalities.
Some of these efforts have thrived. Less than an hour’s drive from Grantsville is one of the most successful and scientifically validated weather-modification operations in the world. The wizard behind the curtain is Richard Blair, CEO and chief bottle washer of Barken Fog Ops, a fog-abatement company in Salt Lake City. The company’s mission: to expunge the crippling cold fogs at Salt Lake City International, which would otherwise shut the airport down. The fogs visit from October to March, anytime a stubborn pool of cold air settles across the Salt Lake Valley between the Wasatch and Oquirrh mountains. Whenever a front of warmer air sweeps over the frigid pool, the result is a fog that hovers roughly 1,000 feet aboveground, socking the airport in.
The first, tiny effort to deal with the problem took place decades ago, when pilots distributed buckets of ice over the fog. As the mix fell, it interacted with suspended water vapor, clearing the fog every time.
Today, working out of a civilian hangar, Blair can be found directing flights most mornings from October through February. Fog Ops has an agreement with Salt Lake City International through its largest operator, Delta Airlines, to banish the fog.
It’s not uncommon for Blair to get a 2 a.m. telephone call asking, “Can you stand by?” By 5 a.m. Blair and his crew—a pilot, a grinder, and a man with a bucket to fill the grinder’s hopper—are ready. As the warm upper atmosphere gains heat under the rising sun, the fog grows ever denser, and Blair’s team heads off to work. They load six insulated boxes of dry ice crystals into the company’s twin-engine Piper Chieftain and fly just above the fog, blanketing the runways.
“We’re usually flying up in the sunshine, just above the fog,” Blair says. “As the aircraft makes a turn you can see a little glint coming from down below as the first ice crystals begin to form. Then a hole opens up in the fog.” Occasionally, Blair says, the atmosphere will become so saturated with supercooled water molecules that the effort kicks off a four-hour snowstorm.
Despite unintended snow, the effort is a raging success. In the end the airlines pay Fog Ops less than $1 in fees for each plane that lands at Salt Lake City International. (They also pay a seasonal retainer.) With some 450 planes arriving daily, and potential losses of $50,000 to $900,000—depending on the particulars of the flight —for each plane that can’t get in or out, the value of fog abatement is staggering. Relatively small payments to Fog Ops provide carriers with the assurance that flights will run regularly and on time.
About 800 miles northeast of Salt Lake City, in the wide-open plains of western North Dakota, hail suppression is the goal. Hail forms inside powerful thunderstorms, often when warm, moist air rises rapidly in the atmosphere. In the Dakotas, these storms can have devastating effects on crops. For more than 30 years, the state of North Dakota has been seeding clouds with silver iodide both to abate the hail and to create rain. “We have eight aircraft standing ready,” says Darin Langerud, director of the North Dakota State Water Commission’s atmospheric research board, “and when conditions are right to promote rain or to suppress hail, they go up.”
“The hail suppression program is one of our great successes,” Langerud says. “We know this because we’ve worked with crop insurance companies for statistics. We compared virtually identical seeded and nonseeded areas of farmland, and the area where the seeding had been done showed a 45 percent lower incidence of hail-damage claims. We’re not saying that hail didn’t fall, but it fell in smaller pieces, which ultimately did less crop damage on the ground.”
Retooling the perfect storm
It is one thing to increase rainfall or reduce the size of hailstones. But when it comes to controlling truly huge, complex, chaotic events like hurricanes and tornadoes, the fix remains theoretical. At least for now, the testing ground is a computer simulation or often just the space inside a physicist’s head.
“With powerful weather forces like hurricanes and tornadoes,” Ross Hoffman of AER says, “the biggest impediment to learning more about them and their structure is that you often can’t get good observations, since the conditions are just too extreme. In many cases the weather you’re hoping to measure renders your instruments unreliable near the event’s peak activity, just when you need them to measure best.” Still, those obstacles haven’t stopped Hoffman and others from hypothesizing how such systems might be modified and then simulating the fix on a computer screen.
Hurricanes, the largest and most damaging weather events, peak in late autumn, when winds coming off the coast of West Africa meet thunderstorms clustered over the warm tropical ocean. The resulting disturbance can form a self-sustaining low-pressure vortex, or what is called a tropical depression; as the system intensifies it becomes a tropical storm. Then, if the winds of this self-sustaining system top 75 miles an hour, it earns a new name: hurricane. In the end, the greater the difference between the temperature of the sea and that of the upper atmosphere, the more powerful the storm.