After a brief(ish) hiatus, Historical Thursday is back! Spring has finally sprung in most places, so what better way to celebrate its and HT’s return than by profiling a device intended to change the very weather above us: the cloud-seeding silver iodide rocket.
Ever get so tired of the rain that you wish you could just make the clouds dump it all out and get it over with? You’re not alone: in July of 1946, Vincent Schaefer, a machinist at General Electric, and Irving Langmuir, a Nobel Laureate, were climbing Mt. Washington in New Hampshire, when they happened upon the conversation topic of weather manipulation. Back at GE’s research lab in Schenectady, New York, Schaefer attempted to test his theory that supercooled water could be converted to ice crystals by filling a small deep freezer chamber with dry ice. Upon breathing on the dry ice mist, the mist turned a rich blue color, and shortly after, the chamber began filling up with microscopic solid crystals.
Building upon Schaefer’s discovery, Dr. Bernard Vonnegut (the older brother of author Kurt Vonnegut) explored ways of chemically converting supercooled water (water that has been cooled to temperatures lower than its typical freezing point of 32 degrees Fahrenheit) into a solid form.
Bernard Vonnegut with his trademark “sunny†disposition
Enter silver iodide, a nifty little inorganic compound with a penchant for turning liquids into solids via a process called heterogeneous nucleation. Nucleation occurs when a given group of ions, atoms, or molecules arrange in the pattern of a crystalline solid. What happens next is the equivalent of molecular peer pressure: a small group of particles acts as a center point for the solid structure formation, and surrounding liquids and gases tend to fall into a similar pattern around said source point. In a process called “cloud seeding,†silver iodide acts as the aforementioned center point. Nearby supercooled water molecules ironically see themselves as “less cool†than silver iodide. So, in trying to conform to silver iodide, who is, like, so totally awesome, water molecules shun their liquid form for a trendier solid look. What results when a ton of small supercooled water particles coalesce together, you ask? Either a raindrop, or a snowflake, depending on the temperature.
One can imagine this occurring on a rather large scale: a cloud stuffed to the gills with moisture suddenly receiving an overdose of cloud laxative is a surefire way to create a rainstorm when and where you want to.
In the coming decades, numerous institutions would capitalize on the usefulness of Schaefer’s and Vonnegut’s research. One such institution was the United States military. In March 1967, the United States Air Force began Operation Popeye during the Vietnam War. Planes bombarded the stratosphere above North Vietnam with silver iodide rockets with the intention of flooding the strategically significant Ho Chi Minh trail and extending the monsoon season. The results were staggering: monsoon seasons from 1967 to 1972 in North Vietnam lasted longer by an average of nearly a month.
Cloud seeding has also been used for far more humanitarian purposes, however. In 1986, Soviet airplanes induced rainfall in weather systems carrying toxic radiation from the Chernobyl disaster toward Moscow. In 2003 and 2004, the appropriately named Weather Modification Inc. conducted cloud seeding operations over drought-affected areas of the Indian state of Maharashtra. Perhaps the most widely publicized occurrence of cloud seeding occurred in 2008, when the Chinese government used silver iodide rockets to release rain outside of Beijing to make for more favorable weather conditions for the Olympics.
Whether it’s being used to combat drought or to waterlog tactical landmarks in warfare, cloud seeding has seen varying uses across the board since its introduction 65 years ago. With a bit of ingenuity, effort, and monetary support, such a technology could be used to dramatically change the climate of communities in need of a good downpour. God knows we’ve got enough of it here in Seattle…
That wraps up the return of Historical Thursday, kludgers and kludgettes! As always, if YOU have an idea for Historical Thursday, drop me a line at thereifixedit@gmail.com!
Check out the entire compendium of Historical Thursday posts here!
Pictures courtesy of Fletcher Boland, Carleton College and SUNY Albany.
from There, I Fixed It – Redneck Repairs
