The US Department of Defense and Meteorological Services in the 1960s carried out missions to cyclone With an ambitious goal, not only observing storms but also changing them.

In the ambitious experiment between 1962 and 1983 with the code name ‘Stormfury’ US Navy pilots made flights to hurricanes by throwing a chemical at the point of maximum winds, believing that in this way they would calm the wild force of the storm.

Six decades after the first flights – and 42 years after the cancellation of the experiment – Stormfury veterans, Golden and Willoughby, talk to the BBC about the results of the experiment.

The first conclusion is that US efforts to control thunderstorms have left behind a controversial heritage that has fueled disbelief and conspiracy theories, with some unanswered questions remaining to date.

From nuclear weapons to experiments for hurricanes

Although at that time a little known about the structure and behavior of the hurricanes, the Navy and the US Army agreed to work with Langmuir’s laboratory in Project Cirrus, which aimed to understand whether sowing technology could help to eliminate their hurricane tropical cyclones before reaching land.

In 1968, satellite images and hurricane detectors combined to give a detailed picture of the storms (Photo: NASA)

Data collected from meteorological balloons and aircraft have shown that hurricane clouds may contain large amounts of over -frozen water.

The Navy had a secret program at China Lake Naval Air Base where they worked on sowing techniques or weather control techniques that were to be used in Laos in Vietnam. These confidential missions, with the code name ‘Popeye business’, were aimed at developing a ‘Weather weapon’ which could cause thunderstorms to rinse the Ho Chi Minh path, the refueling line of the northern Vietnam.

“If they could reduce wind speed by about 10%, this could make a difference in the category of tension when approaching land,” says Willoughby, who began flying to storms surveillance missions to the Pacific for the 1970s Navy in the early 1970s.

If a wind at a speed of 160 km/h could slow down at 80 km/h, it would actually lose 75% of its power.

Hurricane Esther provided the critical test for theory. Emerging around the islands of the Green Cape (Green Cape) in September 1961, the storm became more intense as it swept the Atlantic, about 640 km north of Puerto Rico. On September 16, an aircraft belonging to the US Meteorology Office passed through the Esther’s eye and threw eight silver iodine containers into the furious winds. In a radar watching Esther, US meteorology office aircraft detected a fading. Although other checks showed no change, it was declared successful, Stormfury’s era officially began.

Stormfury’s largest mission took place in 1969. On August 18 and 20, 13 aircraft took part in five flights along the hurricane Debbie, including an Navy A-6 Intruder aircraft, which threw 1,000 silver iodine containers each day.

After almost a decade of incorrect startups, the data they gathered were amazing: the most encouraging was that they recorded a second cyclone eye that emerged after sowing flights, with weaker winds, which matched the case. During the two days of sowing, the winds decreased by 31% and 15%. Stormfury’s director R. Cecil Gentry concluded that there was less than one in 10 chances of course, and his work in Science magazine found that the data suggesting that the storm had been successfully amended by scientists.

The end of Stormfury

Hurricane Debbie was not the springboard for great success as many hoped for the project. The last sowing flight took place in 1971, throwing containers on the wall of Hurricane Ginger without noticeable effect. Later in the same year, the Navy withdrew its support. The departure of the sailor was partly due to the fact that they no longer needed to try it, says Harper: “They used techniques in Vietnam and Laos – they no longer needed to try them in the Atlantic in hurricanes.”

Elements revealed in the Pentagon documents in 1974 showed a much less careful use of silver iodine and similar compounds in Vietnam, Cambodia and Laos, where Air Force and Navy aircraft dropped a total of 47.409 containers in 2,600.

Overall, Stormfury’s flights were “bombed” with iodine silver containers 4 hurricanes on 8 different days. Data from these flights found that in four days, the winds decreased, reducing their speed by 10% or a little more. Other days, nothing happened, which was attributed to the failure of flights to achieve goals or in poorly selected storms.

Stormfury was a humiliating test of reality, says Willoughby, bringing people facing the “huge” energy of a hurricane – estimated to be equivalent to a nuclear bomb of 10 megatons that explodes every 20 minutes. “Maybe someday, one will find a way to artificially weaken hurricanes.”

However, the project provided results that still keep us safe in other ways. “The measurements from the aircraft have taught us a lot about the structure and behavior of hurricanes,” says Joe Golden. “And these data has helped to improve the models of that time.”