In 1952, General Electric published its own "History of Project Cirrus", compiled by Barrington Havens of G.E.'s public relations department. In his introduction, he writes that "[Project Cirrus] was very complex, with a number of subdivisions associated with the main activity. Some of these subdivisions ran consecutively, some operated in parallel, and others intertwined or branched off in variously divergent directions." This preface is relevant to Schaefer's own collection of materials because the "intertwined" nature of Cirrus itself, as well as its roots in Schaefer and Langmuir's previous work, sometimes made it difficult for the archivist to separate Project Cirrus documents from materials that related to cloud seeding efforts but were not strictly part of the work done under the government contract that defined Project Cirrus.
The archivist made every attempt to be strict with materials placed into the Project Cirrus series, using dates, acknowledgements to the military, and the Army Signal Corp's own stamp to help identify documents as Project Cirrus when needed. Researchers may find it helpful to consult the cloud seeding materials in Series #1 for items documenting the events that led to the project's founding.
Project Cirrus bloomed from multiple experiments that converged late in 1946. Vincent Schaefer and Irving Langmuir did extensive work for the United States military during World War II. Among their projects was the issue of precipitation static interfering with U.S. Airforce pilots' ability to fly and land safely. (See Series #1, General Electric) Their efforts to deal with the problem took them to the peak of New Hampshire's Mount Washington, where Schaefer and Langmuir observed behaviors of snow and ice crystals that were relevant to their current work but also gave them ideas for future research regarding supercooled water droplets.
When their contracts with the U.S. military ran out shortly after World War II, Schaefer and Langmuir continued studying behaviors of snow and ice particles in earnest. Schaefer discovered that he could use a type of special plastic called Formvar to capture and preserve snowflakes, some of which can be found in Series #1. These experiments led Schaefer to investigate further the behavior of particles in cloud formations. On a hot July day in 1946, while working with a cold chamber, Schaefer accidentally discovered that the use of dry ice in a supercooled cloud would form instant ice crystals. Drs. Irving Langmuir and Bernard Vonnegut added their expertise to the process, working with silver iodide as well as dry ice. In no time they worked out the potential effects of their discovery on weather modification, and the seeds of Project Cirrus were firmly planted.
Ultimately, on November 13, 1946, Schaefer led a successful cloud seeding expedition over Mount Greylock in Massachusetts. His efforts convinced the U.S. military to sign a contract with General Electric yet again early in 1947. This time, it was a mutual agreement between G.E., the Army Signal Corps of Engineers, the Air Force, and the Office of Naval Research. The government hoped that fruitful cloud seeding experimentation would open doors for agricultural success and even improved safety for the people of the United States. The project sponsored well over 150 flights as well as ground operations, with 1948-1950 being the major years for flights conducted. Besides basic cloud seeding work, they also experimented with hurricane seeding and wildfire fighting in the fall of 1947. The project wrapped up in September 1952 when the Airforce pilots began to be called away to Korea, and the G.E. team decided they had gone as far as they could with their work.
This series is divided into three parts: flight data and research, subject files, and reports and publications. Each one highlights various aspects of G.E.'s efforts to work with the military as they explored cloud seeding options in the late 1940s and early 1950s.