It was questionable how a lot credit score they might take. They’d 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—effectively, battles tended to start out in dry climate, so it was solely the pure cycle of issues that moist climate typically 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 working media battle to debunk the efforts of the self-styled rainmakers who began working throughout the nation.
Probably 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 sequence of picket towers, combine up a secret mix of 23 cask-aged chemical substances, and pour it into vats on prime of the towers to evaporate into the sky. Hatfield’s strategies had the air of witchcraft, however he had a knack for enjoying the percentages. In Los Angeles, he promised 18 inches of rain between mid-December and late April, when historic rainfall information advised a 50 p.c probability of that occuring 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 full of particles, some no greater 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 informed me. The varieties of particles differ by place. Within the UAE, they embrace a fancy 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.
Quite a lot of raindrops begin as airborne ice crystals, which soften as they fall to earth. However with out cloud condensation nuclei, even ice crystals received’t kind till the temperature dips under –40 levels Fahrenheit. In consequence, the environment is stuffed with pockets of supercooled liquid water that’s under freezing however hasn’t really changed into 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 Common Electrical seized on the thought. One group, led by chemists Vincent Schaefer and Irving Langmuir, discovered that strong 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: “Control of Weather.” Inside just a few 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.
