Project Cirrus, First Hurricane Cloud Seeding Experiment

The energy expended by a tropical hurricane is enough to drive all the machinery in the world for three or four years. Yet the Army, the Navy and General Electric Company are collaborating in a daring meteorological experiment which is to determine whether or not the colossal vortex that we call a hurricane can be broken by making it precipitate the thousands of tons of water that it contains. [1]

The cyclone was historically significant in that it was the first tropical cyclone to be modified as part of a multi-year operation called Project Cirrus. In July 1946, General Electric (GE) scientists concluded after experimentation that dry ice seeding could induce heavy rainfall and thus ultimately weaken storms by cooling temperatures in the eye. To undertake Project Cirrus, GE, the United States Army, the Office of Naval Research, and the U.S. Weather Bureau functioned jointly on research and planning. Early on October 13, 1947, 200 pounds (3,200 oz) of dry ice were dropped throughout the storm, then located about 350 mi (560 km) east of Jacksonville, Florida. While the appearance of the clouds changed, the initial results of the seeding were inconclusive. Shortly after the seeding took place, the hurricane turned sharply toward the Southeastern United States. While the move the leading GE scientist later blamed upon the seeding, subsequent examination of the environment surrounding the storm determined that a large upper-level ridge was in fact responsible for the abrupt turn. [2]