The chemtrail conspiracy theory holds that some condensation trails (contrails) are actually toxic chemicals or biological agents deliberately sprayed at high altitude for a purpose undisclosed to the general public.
Versions of the conspiracy theory circulating on the internet and on some radio talk shows theorize that this activity is directed by government officials, and federal agencies have received thousands of complaints from people who have demanded an explanation. The existence of chemtrails has been repeatedly denied by federal agencies and scientists.
The Air Force has stated that the theory is a hoax which "has been investigated and refuted by many established and accredited universities, scientific organizations, and major media publications".
The term chemtrail does not refer to common forms of aerial spraying such as crop dusting, cloud seeding or aerial firefighting. The term specifically refers to aerial trails allegedly caused by the systematic high-altitude release of chemical substances not found in ordinary contrails, resulting in the appearance of supposedly uncharacteristic sky tracks. Believers of this theory speculate that the purpose of the chemical release may be global dimming, population control, or weather control and claim that these trails are causing respiratory illnesses and other health problems.
Overview
The chemtrail conspiracy theory began to circulate in 1996 when the United States Air Force (USAF) was accused of releasing unknown substances from aircraft which were creating unusual contrails. The Air Force says the hoax was fueled in part by authors citing an Air University strategy paper entitled Weather as a Force Multiplier: Owning the Weather in 2025 to allege the Air Force was currently conducting a secret government program to modify the weather. The paper was presented in response to a military directive to anticipate future developments and strategies for maintaining the United States' military dominance in the year 2025 and identified as "fictional representations of future situations/scenarios". The Air Force denies it is actually conducting such experiments or that such experiments are planned, and points to the refutations presented by accredited universities, scientific organizations and major news organizations as further evidence that chemtrails do not exist.