Weather modification is the act of intentionally manipulating or altering the weather. The most common form of weather modification is cloud seeding to increase rain or snow, usually for the purpose of increasing the local water supply. Weather modification can also have the goal of preventing damaging weather, such as hail or hurricanes, from occurring; or of provoking damaging weather against an enemy or rival, as a tactic of military or economic warfare.
Humans have long sought to purposefully alter such atmospheric phenomena as clouds, rain, snow, hail, lightning, thunderstorms, tornadoes, hurricanes, and cyclones. Magical and religious practices to control the weather are attested in a variety of cultures, thousands of years before the modern era.
Weather Modification : Britannica
The modern era of scientific weather modification began in 1946 with work by Vincent J. Schaefer and Irving Langmuir at the General Electric Research Laboratories in Schenectady, New York. Schaefer discovered that when dry ice (frozen carbon dioxide) pellets were dropped into a cloud composed of water droplets in a deep-freeze box, the droplets were rapidly replaced by ice crystals, which increased in size and then fell to the bottom of the box. The Schaefer-Langmuir experiments demonstrated that so-called supercooled clouds, namely those composed of water droplets at temperatures below freezing, could be dissipated. When the supercooled clouds were seeded with grains of dry ice, ice crystals formed and grew large enough to fall out of the clouds. The term used to define this method of weather modification is called cloud seeding.
Further studies found that certain substances other than dry ice can be used to seed clouds. For example, when silver iodide and lead iodide are burned, they create a smoke of tiny particles. These particles produce ice crystals in supercooled clouds below temperatures of about −5° C as the supercooled cloud droplets evaporate. The water vapor is then free to deposit onto the silver iodide or lead iodide crystals. Although many other materials can cause ice crystals to form, the above-mentioned are the most widely used. For the most part, dry ice is dispersed from airplanes, but silver iodide nuclei may be generated on the ground and carried upward by air currents, introduced from airplanes, or produced by pyrotechnic devices such as rockets or exploding artillery shells. Other documented cloud seeding substances include the use of aluminum oxide and barium.
Since the cloud seeding breakthroughs of the 1950s, other methods of manipulating the weather have been researched and applied. These include; fog dissipation, modifying the electricity in clouds, hail suppression, modifying the severity of storms and hurricanes, attempting to control storms and hurricanes. For the purposes of this website I will focus on military applications of weather modification which have been documented.
The first attempt to modify a hurricane began on October 13, 1947. This attempt was code named Project Cirrus. Project Cirrus was a collaboration of the General Electric Corporation, the US Army Signal Corps, the Office of Naval Research, and the US Air Force. An airplane flew along the rain bands of the hurricane, and dropped nearly 180 pounds (82 kilograms) of crushed dry ice into the clouds. The hurricane changed direction and made landfall near Savannah, Georgia. The public blamed the seeding on the United States government. Cirrus was canceled and lawsuits were threatened. This disaster set back the cause of seeding hurricanes for eleven years.