The day of that fifth flight, January 19, 2017, principal investigator Jeff French, an assistant professor of atmospheric science at the University of Wyoming, sat inside a tiny King Air prop plane. The pilot flew to 14,000 feet, then back down a couple thousand. The air just above them was around 5 to 14 degrees Fahrenheit, optimal for the super-cooled liquids needed to make snow. The plane’s radar was humming, as were instruments that collected information on atmospheric pressure, temperature, water vapor, and wind. The measurements poured into a set of computer-processor racks packed into the four-seater, making it look like the inside of a sound booth.