In the skies over Al Ain, in the United Arab Emirates, pilot Mark Newman waits for the signal. When it comes, he flicks a few silver switches on a panel by his leg, twists two black dials, then punches a red button labeled FIRE.

A slender canister mounted on the wing of his small propeller plane pops open, releasing a plume of fine white dust. That dust—actually ordinary table salt coated in a nanoscale layer of titanium oxide—will be carried aloft on updrafts of warm air, bearing it into the heart of the fluffy convective clouds that form in this part of the UAE, where the many-shaded sands of Abu Dhabi meet the mountains on the border with Oman. It will, in theory at least, attract water molecules, forming small droplets that will collide and coalesce with other droplets until they grow big enough for gravity to pull them out of the sky as rain.

This is cloud seeding. It’s one of hundreds of missions that Newman and his fellow pilots will fly this year as part of the UAE’s ambitious, decade-long attempt to increase rainfall in its desert lands. Sitting next to him in the copilot’s seat, I can see red earth stretching to the horizon. The only water in sight is the swimming pool of a luxury hotel, perched on the side of a mountain below a sheikh’s palace, shimmering like a jewel.

More than 50 countries have dabbled in cloud seeding since the 1940s—to slake droughts, refill hydroelectric reservoirs, keep ski slopes snowy, or even use as a weapon of war. In recent years there’s been a new surge of interest, partly due to scientific breakthroughs, but also because arid countries are facing down the early impacts of climate change.

Like other technologies designed to treat the symptoms of a warming planet (say, pumping sulfur dioxide into the atmosphere to reflect sunlight into space), seeding was once controversial but now looks attractive, perhaps even imperative. Dry spells are getting longer and more severe: In Spain and southern Africa, crops are withering in the fields, and cities from Bogotá to Cape Town have been forced to ration water. In the past nine months alone, seeding has been touted as a solution to air pollution in Pakistan, as a way to prevent forest fires in Indonesia, and as part of an effort to refill the Panama Canal, which is drying up.

Apart from China, which keeps its extensive seeding operations a closely guarded secret, the UAE has been more ambitious than any other country about advancing the science of making rain. The nation gets around 5 to 7 inches of rain a year—roughly half the amount that falls on Nevada, America’s driest state. The UAE started its cloud-seeding program in the early 2000s, and since 2015 it has invested millions of dollars in the Rain Enhancement Program, which is funding global research into new technologies.

This past April, when a storm dumped a year’s worth of rain on the UAE in 24 hours, the widespread flooding in Dubai was quickly blamed on cloud seeding. But the truth is more nebulous. There’s a long history of people—tribal chiefs, traveling con artists, military scientists, and most recently VC-backed techies—claiming to be able to make it rain on demand. But cloud seeding can’t make clouds appear out of thin air; it can only squeeze more rain out of what’s already in the sky. Scientists still aren’t sure they can make it work reliably on a mass scale. The Dubai flood was more likely the result of a region-wide storm system, exacerbated by climate change and the lack of suitable drainage systems in the city.

The Rain Enhancement Program’s stated goal is to ensure that future generations, not only in the UAE but in arid regions around the globe, have the water they need to survive. The architects of the program argue that “water security is an essential element of national security” and that their country is “leading the way” in “new technologies” and “resource conservation.” But the UAE—synonymous with luxury living and conspicuous consumption—has one of the highest per capita rates of water use on earth. So is it really on a mission to make the hotter, drier future that’s coming more livable for everyone? Or is this tiny petro-state, whose outsize wealth and political power came from helping to feed the industrialized world’s fossil-fuel addiction, looking to accrue yet more wealth and power by selling the dream of a cure?

I’ve come here on a mission of my own: to find out whether this new wave of cloud seeding is the first step toward a world where we really can control the weather, or another round of literal vaporware.

The first systematic attempts at rainmaking date back to August 5, 1891, when a train pulled into Midland, Texas, carrying 8 tons of sulfuric acid, 7 tons of cast iron, half a ton of manganese oxide, half a dozen scientists, and several veterans of the US Civil War, including General Edward Powers, a civil engineer from Chicago, and Major Robert George Dyrenforth, a former patent lawyer.

Powers had noticed that it seemed to rain more in the days after battles, and had come to believe that the “concussions” of artillery fire during combat caused air currents in the upper atmosphere to mix together and release moisture. He figured he could make his own rain on demand with loud noises, either by arranging hundreds of cannons in a circle and pointing them at the sky or by sending up balloons loaded with explosives. His ideas, which he laid out in a book called War and the Weather and lobbied for for years, eventually prompted the US federal government to bankroll the experiment in Midland.

Powers and Dyrenforth’s team assembled at a local cattle ranch and prepared for an all-out assault on the sky. They made mortars from lengths of pipe, stuffed dynamite into prairie dog holes, and draped bushes in rackarock, an explosive used in the coal-mining industry. They built kites charged with electricity and filled balloons with a combination of hydrogen and oxygen, which Dyrenforth thought would fuse into water when it exploded. (Skeptics pointed out that it would have been easier and cheaper to just tie a jug of water to the balloon.)

The group was beset by technical difficulties; at one point, a furnace caught fire and had to be lassoed by a cowboy and dragged to a water tank to be extinguished. By the time they finished setting up their experiment, it had already started raining naturally. Still, they pressed on, unleashing a barrage of explosions on the night of August 17 and claiming victory when rain again fell 12 hours later.

It was questionable how much credit they could take. They had arrived in Texas right at the start of the rainy season, and the precipitation that fell before the experiment had been forecast by the US Weather Bureau. As for Powers’ notion that rain came after battles—well, battles tended to start in dry weather, so it was only the natural cycle of things that wet weather often followed.

Despite skepticism from serious scientists and ridicule in parts of the press, the Midland experiments lit the fuse on half a century of rainmaking pseudoscience. The Weather Bureau soon found itself in a running media battle to debunk the efforts of the self-styled rainmakers who started operating across the country.

The most famous of these was Charles Hatfield, nicknamed either the Moisture Accelerator or the Ponzi of the Skies, depending on whom you asked. Originally a sewing machine salesman from California, he reinvented himself as a weather guru and struck dozens of deals with desperate towns. When he arrived in a new place, he’d build a series of wooden towers, mix up a secret blend of 23 cask-aged chemicals, and pour it into vats on top of the towers to evaporate into the sky. Hatfield’s methods had the air of witchcraft, but he had a knack for playing the odds. In Los Angeles, he promised 18 inches of rain between mid-December and late April, when historical rainfall records suggested a 50 percent chance of that happening anyway.

While these showmen and charlatans were filling their pocketbooks, scientists were slowly figuring out what actually made it rain—something called cloud condensation nuclei. Even on a clear day, the skies are packed with particles, some no bigger than a grain of pollen or a viral strand. “Every cloud droplet in Earth’s atmosphere formed on a preexisting aerosol particle,” one cloud physicist told me. The types of particles vary by place. In the UAE, they include a complex mix of sulfate-rich sands from the desert of the Empty Quarter, salt spray from the Persian Gulf, chemicals from the oil refineries that dot the region, and organic materials from as far afield as India. Without them there would be no clouds at all—no rain, no snow, no hail.

A lot of raindrops start as airborne ice crystals, which melt as they fall to earth. But without cloud condensation nuclei, even ice crystals won’t form until the temperature dips below -40 degrees Fahrenheit. As a result, the atmosphere is full of pockets of supercooled liquid water that’s below freezing but hasn’t actually turned into ice.

In 1938, a meteorologist in Germany suggested that seeding these areas of frigid water with artificial cloud condensation nuclei might encourage the formation of ice crystals, which would quickly grow large enough to fall, first as snowflakes, then as rain. After the Second World War, American scientists at General Electric seized on the idea. One group, led by chemists Vincent Schaefer and Irving Langmuir, found that solid carbon dioxide, also known as dry ice, would do the trick. When Schaefer dropped grains of dry ice into the home freezer he’d been using as a makeshift cloud chamber, he discovered that water readily freezes around the particles’ crystalline structure. When he witnessed the effect a week later, Langmuir jotted down three words in his notebook: “Control of Weather.” Within a few months, they were dropping dry-ice pellets from planes over Mount Greylock in Western Massachusetts, creating a 3-mile-long streak of ice and snow.

Another GE scientist, Bernard Vonnegut, had settled on a different seeding material: silver iodide. It has a structure remarkably similar to an ice crystal and can be used for seeding at a wider range of temperatures. (Vonnegut’s brother, Kurt, who was working as a publicist at GE at the time, would go on to write Cat’s Cradle, a book about a seeding material called ice-nine that causes all the water on earth to freeze at once.)

In the wake of these successes, GE was bombarded with requests: Winter carnivals and movie studios wanted artificial snow; others wanted clear skies for search and rescue. Then, in February 1947, everything went quiet. The company’s scientists were ordered to stop talking about cloud seeding publicly and direct their efforts toward a classified US military program called Project Cirrus.

Over the next five years, Project Cirrus conducted more than 250 cloud-seeding experiments as the United States and other countries explored ways to weaponize the weather. Schaefer was part of a team that dropped 80 pounds of dry ice into the heart of Hurricane King, which had torn through Miami in the fall of 1947 and was heading out to sea. Following the operation, the storm made a sharp turn back toward land and smashed into the coast of Georgia, where it caused one death and millions of dollars in damages. In 1963, Fidel Castro reportedly accused the Americans of seeding Hurricane Flora, which hung over Cuba for four days, resulting in thousands of deaths. During the Vietnam War, the US Army used cloud seeding to try to soften the ground and make it impassable for enemy soldiers.

A couple of years after that war ended, more than 30 countries, including the US and the USSR, signed the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques. By then, interest in cloud seeding had started to melt away anyway, first among militaries, then in the civilian sector. “We didn’t really have the tools—the numerical models and also the observations—to really prove it,” says Katja Friedrich, who researches cloud physics at the University of Colorado. (This didn’t stop the USSR from seeding clouds near the site of the nuclear meltdown at Chernobyl in hopes that they would dump their radioactive contents over Belarus rather than Moscow.)

To really put seeding on a sound scientific footing, they needed to get a better understanding of rain at all scales, from the microphysical science of nucleation right up to the global movement of air currents. At the time, scientists couldn’t do the three things that were required to make the technology viable: identify target areas of supercooled liquid in clouds, deliver the seeding material into those clouds, and verify that it was actually doing what they thought. How could you tell whether a cloud dropped snow because of seeding, or if it would have snowed anyway?

By 2017, armed with new, more powerful computers running the latest generation of simulation software, researchers in the US were finally ready to answer that question, via the Snowie project. Like the GE chemists years earlier, these experimenters dropped silver iodide from planes. The experiments took place in the Rocky Mountains, where prevailing winter winds blow moisture up the slopes, leading to clouds reliably forming at the same time each day.

The results were impressive: The researchers could draw an extra 100 to 300 acre-feet of snow from each storm they seeded. But the most compelling evidence was anecdotal. As the plane flew back and forth at an angle to the prevailing wind, it sprayed a zigzag pattern of seeding material across the sky. That was echoed by a zigzag pattern of snow on the weather radar. “Mother Nature does not produce zigzag patterns,” says one scientist who worked on Snowie.

In almost a century of cloud seeding, it was the first time anyone had actually shown the full chain of events from seeding through to precipitation reaching the ground.

The UAE’s national Center of Meteorology is a glass cube rising out of featureless scrubland, ringed by a tangle of dusty highways on the edge of Abu Dhabi. Inside, I meet Ahmad Al Kamali, the facility’s rain operations executor—a trim young man with a neat beard and dark-framed glasses. He studied at the University of Reading in the UK and worked as a forecaster before specializing in cloud-seeding operations. Like all the Emirati men I meet on this trip, he’s wearing a kandura—a loose white robe with a headpiece secured by a loop of thick black cord.

We take the elevator to the third floor, where I find cloud-seeding mission control. With gold detailing and a marble floor, it feels like a luxury hotel lobby, except for the giant radar map of the Gulf that fills one wall. Forecasters—men in white, women in black—sit at banks of desks and scour satellite images and radar data looking for clouds to seed. Near the entrance there’s a small glass pyramid on a pedestal, about a foot wide at its base. It’s a holographic projector. When Al Kamali switches it on, a tiny animated cloud appears inside. A plane circles it, and rain begins to fall. I start to wonder: How much of this is theater?

The impetus for cloud seeding in the UAE came in the early 2000s, when the country was in the middle of a construction boom. Dubai and Abu Dhabi were a sea of cranes; the population had more than doubled in the previous decade as expats flocked there to take advantage of the good weather and low income taxes. Sheikh Mansour bin Zayed Al Nahyan, a member of Abu Dhabi’s royal family—currently both vice president and deputy prime minister of the UAE—thought cloud seeding, along with desalination of seawater, could help replenish the country’s groundwater and refill its reservoirs. (Globally, Mansour is perhaps best known as the owner of the soccer club Manchester City.) As the Emiratis were setting up their program, they called in some experts from another arid country for help.

Back in 1989, a team of researchers in South Africa were studying how to enhance the formation of raindrops. They were taking cloud measurements in the east of the country when they spotted a cumulus cloud that was raining when all the other clouds in the area were dry. When they sent a plane into the cloud to get samples, they found a much wider range of droplet sizes than in the other clouds—some as big as half a centimeter in diameter.

The finding underscored that it’s not only the number of droplets in a cloud that matters but also the size. A cloud of droplets that are all the same size won’t mix together because they’re all falling at the same speed. But if you can introduce larger drops, they’ll plummet to earth faster, colliding and coalescing with other droplets, forming even bigger drops that have enough mass to leave the cloud and become rain. The South African researchers discovered that although clouds in semiarid areas of the country contain hundreds of water droplets in every cubic centimeter of air, they’re less efficient at creating rain than maritime clouds, which have about a sixth as many droplets but more variation in droplet size.

So why did this one cloud have bigger droplets? It turned out that the chimney of a nearby paper mill was pumping out particles of debris that attracted water. Over the next few years, the South African researchers ran long-term studies looking for the best way to re-create the effect of the paper mill on demand. They settled on ordinary salt—the most hygroscopic substance they could find. Then they developed flares that would release a steady stream of salt crystals when ignited.

Those flares were the progenitors of what the Emiratis use today, made locally at the Weather Modification Technology Factory. Al Kamali shows me a couple: They’re foot-long tubes a couple of inches in diameter, each holding a kilogram of seeding material. One type of flare holds a mixture of salts. The other type holds salts coated in a nano layer of titanium dioxide, which attracts more water in drier climates. The Emiratis call them Ghaith 1 and Ghaith 2, ghaith being one of the Arabic words for “rain.” Although the language has another near synonym, matar, it has negative connotations—rain as punishment, torment, the rain that breaks the banks and floods the fields. Ghaith, on the other hand, is rain as mercy and prosperity, the deluge that ends the drought.

The morning after my visit to the National Center of Meteorology, I take a taxi to Al Ain to go on that cloud-seeding flight. But there’s a problem. When I leave Abu Dhabi that morning there’s a low fog settled across the country, but by the time I arrive at Al Ain’s small airport—about 100 miles inland from the cities on the coast—it has burned away, leaving clear blue skies. There are no clouds to seed.

Once I’ve cleared the tight security cordon and reached the gold-painted hangar (the airport is also used for military training flights), I meet Newman, who agrees to take me up anyway so he can demonstrate what would happen on a real mission. He’s wearing a blue cap with the UAE Rain Enhancement Program logo on it. Before moving to the UAE with his family 11 years ago, Newman worked as a commercial airline pilot on passenger jets and split his time between the UK and his native South Africa. He has exactly the kind of firmly reassuring presence you want from someone you’re about to climb into a small plane with.

Every cloud-seeding mission starts with a weather forecast. A team of six operators at the meteorology center scour satellite images and data from the UAE’s network of radars and weather stations and identify areas where clouds are likely to form. Often, that’s in the area around Al Ain, where the mountains on the border with Oman act as a natural barrier to moisture coming in from the sea.

If it’s looking like rain, the cloud-seeding operators radio the hangar and put some of the nine pilots on standby mode—either at home, on what Newman calls “villa standby,” or at the airport or in a holding pattern in the air. As clouds start to form, they begin to appear on the weather radar, changing color from green through blue to yellow and then red as the droplets get bigger and the reflectivity of the clouds increases.

Once a mission is approved, the pilot scribbles out a flight plan while the ground crew preps one of the four modified Beechcraft King Air C90 planes. There are 24 flares attached to each wing—half Ghaith 1, half Ghaith 2—for a total of 48 kilograms of seeding material on each flight. Timing is important, Newman tells me as we taxi toward the runway. The pilots need to reach the cloud at the optimal moment.

Once we’re airborne, Newman climbs to 6,000 feet. Then, like a falcon riding the thermals, he goes hunting for updrafts. Cloud seeding is a mentally challenging and sometimes dangerous job, he says through the headset, over the roar of the engines. Real missions last up to three hours and can get pretty bumpy as the plane moves between clouds. Pilots generally try to avoid turbulence. Seeding missions seek it out.

When we get to the right altitude, Newman radios the ground for permission to set off the flares. There are no hard rules for how many flares to put into each cloud, one seeding operator told me. It depends on the strength of the updraft reported by the pilots, how things look on the radar. It sounds more like art than science.

Newman triggers one of the salt flares, and I twist in my seat to watch: It burns with a white-gray smoke. He lets me set off one of the nano-flares. It’s slightly anticlimactic: The green lid of the tube pops open and the material spills out. I’m reminded of someone sprinkling grated cheese on spaghetti.

There’s an evangelical zeal to the way some of the pilots and seeding operators talk about this stuff—the rush of hitting a button on an instrument panel and seeing the clouds burst before their eyes. Like gods. Newman shows me a video on his phone of a cloud that he’d just seeded hurling fat drops of rain onto the plane’s front windows. Operators swear they can see clouds changing on the radar.