“Fire left,” instructs Pederson. Mistry flips a switch on the center console and deploys a flare on the left wing. “Fire right.” There are 24 cylinders resembling sticks of dynamite wired to racks on the plane’s wings, 12 on each. The flares are filled with combustible sodium chloride—pulverized table salt mixed with a flammable potassium powder. When the switch is flipped, the end of the flare shoots orange fire and trillions of superfine salt particles are released into the cloud. Water molecules are attracted to salt, so they bond to the particles and coalesce into raindrops. ... During our mission over Maharashtra, we have cooperative clouds. Twenty-two minutes after seeding the first cloud, Pederson returns to the location where he fired that initial flare. It’s pouring. “We’ve got drops!” he shouts. He dips the King Air into a victory swoop before gunning over to another cluster of clouds. My stomach churns, and I can’t hold it in any longer; I heave into my purse. Pederson doesn’t notice. The computer barks out another warning about excessive banking. He laughs and says, “Shove it, Betty.” ... Cloud seeding has been controversial since it was invented by Vincent Schaefer in 1946. A chemist for General Electric, Schaefer made the first snowstorm in a laboratory freezer. The media predicted that cloud seeding could perform miracles, from dousing forest fires to ensuring white Christmases. But doubts quickly arose about the impact of meddling with nature. Concerns that cloud seeding might “steal” water from an area a cloud is traveling toward—robbing Peter to water Paul, as it were—have been dispelled. Storm clouds continually regenerate and release only a portion of their moisture when they rain, which means you can’t “wring out” all the moisture from one cloud.
For decades, sewage has been treated and used for irrigating crops, parks, and golf courses, but making it fit for human consumption requires a much more rigorous filtration technology using polymer membranes. No thicker than a human hair, the membranes are at once delicate and durable. Using pores smaller than one-millionth of a millimeter, they’re capable of wiping out microscopic contaminants. ... the water division at Dow Chemical, he pulls in more than $1 billion in sales annually. The membrane market is growing more than 10 percent a year in part because of increasing water scarcity worldwide and ever more pressure to develop drought-proof water supplies from new sources. ... The whole concept of recycled sewage might be harder to swallow if there weren’t already so much sewage in the water sources we routinely draw from. ... the very reason chemists created these synthetic membranes decades ago is that, increasingly, humans have been contaminating the water supply. Industries have emerged, meanwhile, that need purer water for manufacturing. Most major players in the automotive, beer and wine, food processing, petrochemical, pharmaceutical, and semiconductor industries, for example, rely on water purified by membranes. ... recycling wastewater is about half the cost of desalinating ocean water: Both use RO membranes, but the salinity of ocean water is much higher, so it’s harder and much more energy-intensive to pump it through the tiny holes.