Weather modification, a brief history

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. Weather modification in warfare has been banned by the United Nations.

Cloud seeding is a common technique to enhance precipitation. Evidence on its safety is strong, but there are still doubts about its effectiveness. Cloud seeding entails spraying small particles (like silver iodide) onto clouds in order to affect their development, usually with the goal of increasing precipitation. Cloud seeding only works to the extent that there is already water vapor present in the air. Critics generally contend that claimed successes occur in conditions which were going to lead to rain anyway. It is used in a variety of drought-prone countries, including the United States, the People's Republic of China, India, and Russia. In the People's Republic of China there is a perceived dependency upon it in dry regions, and there is a strong suspicion it is used to "wash the air" in dry and heavily polluted places, such as Beijing. In mountainous areas of the United States such as the Rocky Mountains and Sierra Nevada, cloud seeding has been employed since the 1950s.

On 13 Oct 1947, the U.S. Military (as part of Project Cirrus involving General Electric) dropped 80 kg of dry ice into a hurricane in the Atlantic Ocean, safely off the eastern coast of the USA. The hurricane changed direction and traveled inland, where it did extensive damage to property in Georgia. The U.S. military classified the data from the seeding of this hurricane to frustrate litigation.
Langmuir believed that there was approximately a 99% probability that this hurricane's change of direction was the result of the cloud seeding. Langmuir's opinion about the effect of the cloud seeding on this hurricane is not mentioned in any of his publications in scientific journals, but is mentioned in the 1953 final report on Project Cirrus, which was classified by the U.S. Military. It is likely that attorneys for General Electric directed Langmuir not to make any public admission that cloud seeding caused the hurricane to change direction, in order to avoid litigation against General Electric by victims of the hurricane.

New Mexico between November 1949 and July 1951. Langmuir claimed that the release of silver iodide modified the weather, not only in the state of New Mexico, but also more than 1000 kilometers downwind. Langmuir's claim was rejected by the meteorological community, because Langmuir's evidence was inadequate.
The release of  silver iodide AgI "was discontinued in July, 1951 during the great floods in Kansas and adjacent states. The 13 July 1951 flood at Kansas City was described as "the most devastating flood in the nation's history"; 17 people died as a direct result of that flood, despite weather forecasts and warnings. (Alexander, 1951) It is still unknown what effect, if any, the AgI release in New Mexico had on rain and floods in Kansas.

The modern consensus of meteorologists seems to be that the release of AgI in New Mexico probably had no effect on the rainfall/floods in Kansas, but if there was an effect, the effect would be only a small enhancement of the total rainfall.
Langmuir sincerely believed that AgI release was modifying weather at long distances from the point of release, yet he continued to engage in such weather modification for two years, despite the possibility of harm from such modification, and despite the lack of consent by affected people.

Despite Langmuirs mixed results modification of the weather was still believed to be achievable. Project Stormfury was an attempt to weaken tropical cyclones by flying aircraft into storms and seeding the eyewall with silver iodide. The project was run by the United States Government from 1962 to 1983. A similar project using soot was run in 1958, with inconclusive results. Various methods have been proposed to reduce the harmful effects of hurricanes. Moshe Alamaro of the Massachusetts Institute of Technology proposed using barges with upward-pointing jet engines to trigger smaller storms to disrupt the progress of an incoming hurricane; critics doubt the jets would be powerful enough to make any noticeable difference.

Alexandre Chorin of the University of California, Berkeley, proposed dropping large amounts of environmentally friendly oils on the sea surface to prevent droplet formation. Experiments by Kerry Emanuel of MIT in 2002 suggested that hurricane-force winds would disrupt the oil slick, making it ineffective. Other scientists disputed the factual basis of the theoretical mechanism assumed by this approach. The Florida company Dyn-O-Mat proposes the use of a product it has developed, called Dyn-O-Gel, to reduce the strength of hurricanes.

The substance is a polymer in powder form which reportedly has the ability to absorb 1,500 times its own weight in water. The theory is that the polymer is dropped into clouds to remove their moisture and force the storm to use more energy to move the heavier water drops, thus helping to dissipate the storm. When the gel reaches the ocean surface, it is reportedly dissolved. The company has tested the substance on a thunderstorm, but there has not been any scientific consensus established as to its effectiveness. Hail cannons have been used by some farmers since the 19th century in an attempt to ward off hail, but there is no reliable scientific evidence to confirm their effectiveness. Another new anti-hurricane technology is a method for the reduction of tropical cyclones’ destructive force  pumping sea water into and diffusing it in the wind at the bottom of such tropical cyclone in its eyewall.
Between 1962 and 1983 Project STORMFURY  seeded eight hurricanes with silver iodide. The theory was that it would cause super cooled water in the hurricane to freeze cause rain bands around the eyewall to grow rapidly and essentially "smother" the eyewall. It didn't work simply because there was not sufficient super cooled water in a hurricane and on the few occasions where it seemed to work, the old eyewall died and was replaced with a new one - sometime which has turned out to be a natural feature in major hurricanes.

In 2008, the Department of Homeland Security (DHS) started investigating ways to collaborate with scientists in an effort to moderate the land damage hurricanes can cause, as well as modifying a hurricane’s path and reducing their intensity. Ultimately, DHS decided not to invest in field tests and new technologies for weather modification was dropped. One reason for this, according to William Laska, program manager at the DHS’s Science and Technology Division, is that “geo-engineering” remains “distasteful” to many scientists and government agencies. Referring to how Project Stormfury has intensified the reluctance to investigate and fund technologies for hurricane modification, William Laska told Earth Magazine:

"Waving the modification/mitigation flag we got a lot of doors slammed in our face." She added, "There’s still a sour taste from Stormfury."

Judging by the effects of Hurricane Sandy and the amount of money in damages a hurricane can cause. It may be possible in theory to rob the heat of a hurricane thus dissipating the energy a super storm regardless of the eyewall regrowing or not. The theory is to have a large plane with a big tank of liquid nitrogen as a refrigerant to constantly cool the store of heat energy, which is usually the fuel that makes a hurricane devastating.
Other methods such as ionizing the air to discharge lightning, by using lasers or soot particles to prevent convectional currents, have been discussed by experts in in hope of preventing extreme weather conditions.
Perhaps in the future the research into weather modification will allow the prevention of hurricanes, reducing the the cost of damages. By then then project storm fury would be remembered as a pioneering project that pave way to weather projects that helped save lives...