It was questionable how a lot credit score they might take. That they had arrived in Texas proper at first of the wet season, and the precipitation that fell earlier than the experiment had been forecast by the US Climate Bureau. As for Powers’ notion that rain got here after battles—nicely, battles tended to begin in dry climate, so it was solely the pure cycle of issues that moist climate usually adopted.
Regardless of skepticism from severe scientists and mock in components of the press, the Midland experiments lit the fuse on half a century of rainmaking pseudoscience. The Climate Bureau quickly discovered itself in a operating media battle to debunk the efforts of the self-styled rainmakers who began working throughout the nation.
Essentially the most well-known of those was Charles Hatfield, nicknamed both the Moisture Accelerator or the Ponzi of the Skies, relying on whom you requested. Initially a stitching machine salesman from California, he reinvented himself as a climate guru and struck dozens of offers with determined cities. When he arrived in a brand new place, he’d construct a collection of picket towers, combine up a secret mix of 23 cask-aged chemical substances, and pour it into vats on high of the towers to evaporate into the sky. Hatfield’s strategies had the air of witchcraft, however he had a knack for enjoying the chances. In Los Angeles, he promised 18 inches of rain between mid-December and late April, when historic rainfall data advised a 50 % likelihood of that taking place anyway.
Whereas these showmen and charlatans had been filling their pocketbooks, scientists had been slowly determining what really made it rain—one thing known as cloud condensation nuclei. Even on a transparent day, the skies are filled with particles, some no larger than a grain of pollen or a viral strand. “Each cloud droplet in Earth’s environment shaped on a preexisting aerosol particle,” one cloud physicist advised me. The forms of particles range by place. Within the UAE, they embody a posh mixture of sulfate-rich sands from the desert of the Empty Quarter, salt spray from the Persian Gulf, chemical substances from the oil refineries that dot the area, and natural supplies from as far afield as India. With out them there could be no clouds in any respect—no rain, no snow, no hail.
Plenty of raindrops begin as airborne ice crystals, which soften as they fall to earth. However with out cloud condensation nuclei, even ice crystals gained’t type till the temperature dips beneath –40 levels Fahrenheit. Consequently, the environment is stuffed with pockets of supercooled liquid water that’s beneath freezing however hasn’t really became ice.
In 1938, a meteorologist in Germany advised that seeding these areas of frigid water with synthetic cloud condensation nuclei may encourage the formation of ice crystals, which might rapidly develop massive sufficient to fall, first as snowflakes, then as rain. After the Second World Battle, American scientists at Basic Electrical seized on the concept. One group, led by chemists Vincent Schaefer and Irving Langmuir, discovered that stable carbon dioxide, also called dry ice, would do the trick. When Schaefer dropped grains of dry ice into the house freezer he’d been utilizing as a makeshift cloud chamber, he found that water readily freezes across the particles’ crystalline construction. When he witnessed the impact every week later, Langmuir jotted down three phrases in his pocket book: “Management of Climate.” Inside a couple of months, they had been dropping dry-ice pellets from planes over Mount Greylock in Western Massachusetts, making a 3-mile-long streak of ice and snow.
