Raising stormfury
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.

After studying this dynamic, Hoffman suggested a scheme to weaken a hurricane or shift its path by heating and cooling the atmosphere in complex patterns. While his plan would, theoretically, help tame the weather, we have no reliable way to heat or cool the atmosphere over large enough areas to move a massive storm. “So today,” Hoffman says, “while I can demonstrate that steering a hurricane is possible using computer simulations, we still don’t have a practical way to do it.”

Another hurricane-moderating hy­­poth­­esis, this one advanced by Daniel Rosenfeld of Hebrew University of Jerusalem and William Woodley, an independent weather-modification researcher based in Colorado, holds that seeding a hurricane’s lower reaches with microscopic dust particles—perhaps microbits of salt—would generate minute water droplets by giving the vapor something to attach to. The droplets would eventually be carried into the storm’s higher altitude, cooling the hurricane through evaporation in the same manner that sweat cools human skin. As the droplets evaporated, they would cool the air in the lower levels of the storm, diminishing its intensity. “Our simulations show that this would be the outcome,” Woodley says.

Tell it to the judge
Even as enhanced computer modeling and more precise measurement bring control of extreme weather closer, those pushing the envelope find themselves facing the same hurdle as Bernard Vonnegut and his colleagues at General Electric half a century ago: the risk of getting sued.

“So here we are, back to weather modification’s critical issue,” says Michael Garstang, distinguished research professor emeritus of environmental sciences at the University of Virginia. “If you cannot predict very precisely what would have happened with, say, a hurricane before you began manipulating it, you’ve left yourself wide open to litigation. There’s just too big an opportunity for people to say: ‘You created this. You made it worse.’”

Charles Hosler agrees. “That’s exactly why there will never be large-scale weather modification or weather control in America. All weather is good for somebody and bad for somebody else.” When altered weather causes a problem for people, he contends, those people are likely to sue.

On this subject Hosler speaks from experience. Along with colleagues, he was once sued by a sightseer riding a ski lift. After the lift’s motor was hit and halted by lightning, the man jumped rather than wait for rescuers; on landing, he broke his leg. Then he discovered that Hosler and his team had been studying thunderclouds nearby. Soon all parties were involved in a lawsuit that was eventually tossed out of court.

Hosler recalls another colleague, this one working in hail abatement research in Pennsylvania, who ran afoul of local fruit farmers who worried that the effort might cause a drought and ruin their livelihood. They reacted by shooting bullets into the sky, hitting a plane flown by student pilots. “People, they get really emotional about their weather,” Hosler says.

If getting sued over a little lightning has some scientists in a tizzy, imagine the risk for those who seek to change the climate in a major way. Nevertheless, some mavericks feel we have no choice as we deal with global warming. Astrophysicist Gregory Benford of the University of California at Irvine, for instance, suggests dispersing tiny particles into the upper atmosphere to reflect sunlight away from us.

And then there’s Roger Angel, an astronomer and optical scientist at the University of Arizona who, working under a NASA grant, seeks to launch trillions of two-foot-wide disks of transparent film into orbit around Earth, a million miles up. The disks, each 250 nanometers thick and tended by “sheepdog” spacecraft to keep them in place, would shade us just enough to reduce sunlight by roughly 2 percent, cooling the planet back to preindustrial temperatures and perhaps moderating some of the destructive weather we have had in recent years.

“I estimate that the program would take 20 years and cost about $5 trillion,” Angel says. But what if, once shaded, Earth begins to overcool? Angel has a contingency there. “Over time, these disks will want to drift out of orbit. We could make it so they stayed in place for only so long.”

Who will stop the Beijing rain? On the 8th of August, 91,000 people will be sitting in an open-air stadium in Beijing for the start of the 2008 Summer Olympics. With thousands of athletes in competition and millions of people watching the event on television, the last thing the Chinese government wants is a rainstorm to spoil this well-planned spectacle.

Tinkering with the weather is old hat for the Chinese, who have employed various cloud-busting techniques to trigger rainfall in their drought-plagued northern provinces, an area that includes Beijing, since the 1950s. For the Olympics, the world’s largest weather modification bureau will set up several banks of rocket launchers outside the city to blast threatening clouds with silver iodide and force them to release their rain before it reaches the Olympic stadium. The bureau has also been practicing a less well-honed strategy that involves overseeding the clouds to actually prevent rainfall; this technique increases the number of ice crystals in a cloud but decreases their mean size, which makes them less likely to fall as rain.

“None of these techniques is a proven technology,” says Roelof Bruintjes, an expert in weather modification at the National Center for Atmospheric Research in Colorado. “I am very skeptical of their having any chance of success.” Of course, the Chinese know full well that weather control is still more art than science. They are just hoping to beat the odds, which, according to historical records, call for a 50 percent chance of rain sometime during the events.

Patrick Huyghe

The high cost of weather
When the wrong weather hits the wrong region at the wrong time, the human and economic consequences can be devastating. Here is a list of the most costly events in recent times:

- Hurricane Mitch, an unusually slow-moving storm, ambled into Central America in 1998 and dumped almost six feet of rain, primarily on Honduras and Nicaragua. The combination of ferocious winds, heavy rainfall, flooding, and mud slides added up to more than 10,000 deaths, millions left homeless, and more than $5 billion in damage.

- The European heat wave of 2003 is estimated to have cost 35,000 to 50,000 lives, and its accompanying drought brought notable crop shortfalls. It is worth remembering, however, that drought in one part of a country is sometimes balanced by excess rain elsewhere.

- Hurricane Katrina, which hit New Orleans and the Gulf Coast in 2005, is in a class by itself: In addition to the loss of life, it caused $40 billion in insurance losses. Thirty oil platforms and nine refineries were destroyed or forced to shut down, and tens of thousands of jobs were lost. Some estimates place the eventual total cost of the disaster at $200 billion.

- The Australian drought of 2006–2007 sliced about 1 percent off the country’s total economic output over the last few years, at the same time reducing wheat production and devastating farm incomes.

-Carl Brenner