|Some dare call it|
Contrails are clouds of water formed by hot airplane exhaust in cold skies.
Chemtrails are an alleged conspiracy by which cranks claim that aircraft contrails are a form of chemical dispersal through which the government is attempting to poison people from above. This is a relatively recent conspiracy theory, having been first discussed around 1996, and is still going strong despite the evidence for the conspiracy being laughably lacking.
Contrails are formed when hot exhaust gases mix with rarefied cool air. In a process similar to cloud formation, the water present in the exhaust freezes quickly, forming a white haze which is essentially - and merely - an elongated cloud. Since this process generally completes several hundred feet behind the aircraft, passengers on commercial airliners typically do not see contrails forming, giving weight to the claim that "chemtrails" only come from special military aircraft. Commercial planes also, of course, don't have windows that face the rear. This feature of contrails can often be seen in photos of purported chemtrails. However, the fact that there is a gap between the aircraft and the formation of the contrail is completely inconsistent with the idea that the planes are pumping out particulate matter and chemicals into the air as one would expect to see the trail form immediately behind the aircraft.
Note that contrails are different than the grayish "vapor trails" sometimes seen when flying low with flaps extended. These are formed of liquid water from compression of moist air under the wing.
On days when cirrus cloud formation is occurring, there is more moisture in the upper atmosphere, and consequently, contrails may linger longer before evaporating. Since cirrus clouds often precede a general overcast or haze, the casual observer could easily assume that the contrails have caused the overcast, or become the overcast.
Contrails have been photographed for many decades, and there are many WWII photographs available on the internet showing aircraft, such as B-17 bombers, with contrails. 
 Chemtrail history and culture
Chemtrail theories were first brought to prominence in the 1990s by paranormal pusher and talk radio host Art Bell. Aided by the internet, it is now a world wide phenomenon and chemtrail watchers all over the globe exchange photographs and videos of their favorite contrails on forums and youtube.
Chemtrails were mentioned in US House Bill HR2977, October 2, 2001, which banned various types of weapons in space. The reference to chemtrails was eventually removed, but the original inclusion is cited as evidence that they are a real phenomenon. Given that the original bill was introduced by Dennis Kucinich, it perhaps reveals more about Kucinich than about whether chemtrails are real.
The chemtrail conspiracy is most popular among those familiar with the New World Order and who claim that the spray is designed to pacify populations, either by making them sick, or some sort of mind control. Like many other pseudoscientific terms, earnest use of the word "chemtrails" immediately identifies the person using it as a crank, and is enough to harm credibility and provoke ridicule among those of a more rationalist disposition.
The supposed purpose of the chemtrail campaign is admittedly unknown, but speculation includes:
- Sterilization for genocide or population control
- Administration of drugs for mind-control or pacification
- Suppression of human evolution
- To combat and control climate change 
- To mask the appearance of Planet X/Nibiru
- Various activities associated with grand conspiracy theories.
The alleged composition of chemtrails varies from one wingnut to another. According to the website of chemtrail "expert" Clifford Carnicom, they may contain barium, calcium, magnesium, titanium, metallic salts, and microscopic fibers. Another site claims they are composed of “an oil based substance of unknown content” and “unknown biological components”.
The alleged effects of chemtrails are incredibly varied. A claim of increase in respiratory diseases is common. Weather alteration is often mentioned. In chemtrail site forums nearly every unexplained headache or car-windshield spot is attributed to chemtrails.
It is known that barium (supposedly included in chemtrails) has the ability to prevent activation of certain T-cells, although this process is reversible and not a proven in vivo effect of barium exposure. This has been made to fit into a wider secret plan to weaken the immune systems of the chemtrail targets.
 Photo evidence
Some photographic evidence of chemtrails supposedly exists, and is often touted around forums dedicated to the conspiracy. One particular photo shows what appears to be ominous looking tanks of "stuff" inside a commercial jet airliner. However, leaving Paranoiaville and landing in Realityland, the image is of flight testing equipment. Tanks of water are used to simulate the weight of passengers (without using real people) and the fluidity and pumping equipment allows the weight distribution to be altered. Other photographic "evidence" is just what it looks like; normal contrails of exhaust gases and condensed water vapor. More dramatic trails can be generated by injecting water into jet engines to create a more "smoky" exhaust either during take-off or for testing purposes.
 Black ray
In the event that an aircraft is flying directly away from the setting or rising sun, the contrail may cause a spectacular crepuscular ray, known in chemtrail jargon as the "black ray", after its sinister appearance. This has little to do with the chemicals sprayed into the contrail and everything to do with how the shadows work. A contrail can block out a significant amount of the sun, and this casts a shadow which is what is usually interpreted by conspiracy nuts as a chemical change.
There are three main types of shadow that can occur due to contrails - and mostly they look a little odd because people aren't quite used to working with shadows in three dimensions. The first is self-shadowing, which is simply the effect of the contrail cloud having volume, so develops a shadowed edge. This is particularly noticeable when the contrail is struck at certain low angles by the sun, or the atmospheric conditions are right to give the contrail a large, voluminous appearance. Parallel shadows give the illusion that a second, darker contrail is accompanying the brighter main one - but this is just the effect of the contrail casting a shadow onto a lower-lying and thin layer of cloud. This isn't helped by the distances involved playing tricks with depth perception, but isn't anything special and is observed whenever high clouds cast shadows onto thin layers of cloud or haze, sometimes producing multiple shadows when conditions are right.
Most black ray contrails are due to volumetric shadows, so called because the shadow isn't cast on an object but through the atmosphere, slightly darkening the natural haze there. All shadows are volumetric in this manner, but when the observer is positioned to see it edge-on, the effect is to visibly darken the atmosphere. When aligned just right, this shadow can look like a darkened continuation of the contrail itself, and moving even slightly can reveal the "black ray" to be a simple illusion. With this in mind, all photos of "black rays" become quite apparent.
 Germany admits to it!
At least one YouTube clip claims to show a German news agency lifting the lid on military planes generating chemtrails and spraying barium into the atmosphere, according to the English subtitles. The actual German audio tells a rather different story: it's not about weather manipulation and chemicals, but about chaff deployed from fighter planes during military exercises that were falsely registered as rain clouds on meteorological radars.
Here is a step-by-step instruction how to fabricate your very own "proof" of chemtrails, much like the above video:
- Pick a somewhat sensationalist news item about the use of chaff by the German military from a German TV station known for broadcasting low-budget movies and softcore porn. Don't worry, most people won't know that this isn't actually reliable news reporting in the first place.
- Add English subtitles, conveniently replacing all occurrences of "chaff" (German "Düppel") with "chemtrail", relying on the fact that the majority of your audience won't know that the German word for "chemtrail" is, well, "chemtrail". (If they knew, they might just notice that the word doesn't occur at all in the clip.) Make it appear as if the report is about actual "clouds" of chemicals, rather than false positives showing up only on radar screens.
- Add some subtle mistranslations that make it appear as if there is some form of evil intent behind all of this. Why talk about unintended distortions in radar images, when adding a slight twist will allow you to accuse the military of actively counterfeiting them?
- Replace more words in your subtitles, for example write climate instead of the more boring and mundane weather radar. Remember: your audience doesn't understand German, so you're free to sell them anything you want and someone is bound to make a connection to HAARP. Just make it marginally fit the video image.
- Upload on Youtube, hyping it as a "Mainstream Media Exposé".
 Vinegar warriors
There are an intrepid group of people who have discovered the secret to removing chemtrails: vinegar. There are numerous groups dedicated to it, and despite the obvious stupidity of it all, they seem to believe it. The trick is as follows; simply evaporate a certain amount of vinegar each day in order to disperse clouds and chemtrails and to clear the skies. Depending on how crazy the person proposing this can be, the volumes range from a few litres per day (mixed with extra water) to simply spraying it into the air from a bottle. Yes, that's right, people believe that clouds and chemicals at 20,000 ft can be dispersed and neutralised by spraying a couple of millilitres of dilute acetic acid in their back yard - presumably the patches of dead grass you can see in the videos these people produce are just a coincidence. For those who can't quite afford the increase in energy bills associated with boiling 5+ litres of water a day for no reason, other advice includes simply tipping it onto asphalt to let it evaporate naturally. Complaints from neighbours about the smell aren't usually mentioned.
There's relatively little to refute when it comes to this. Not least the complete lack of evidence that chemtrails are real, but even if they were real, there's no chance that spraying a minute amount of a fairly cheap weak acid is going to disperse chemicals over a range of dozens of cubic miles. Proponents do present evidence that their actions do work: the "chemtrails" eventually dissipate over time, about 10-30 minutes after spraying or evaporating the vinegar. You know, exactly the same way they do when you don't spray the vinegar. Then again, these are people who think spraying a minute amount of acetic acid and water into the air will break up a cloud a few miles away - so don't expect them to understand the concept of a controlled experiment.
 Chemtrail conspiracies make no sense
The very existence of the Grand Conspiracy required to administer chemtrails may be challenged on the basis of the difficulty of maintaining such a conspiracy for so long. Aerial spraying from high-altitude would be an extremely inefficient and inexact mode of delivering chemicals to ground-based targets. Pesticides, for example, are often sprayed on crops from airplanes flying at thirty feet. Wide-area mosquito spraying may be done from an altitude of 150 feet. Chemtrails are supposedly deposited at 30,000 feet or higher, where winds would likely disperse them unpredictably. If there were a campaign to introduce foreign chemicals to the population, it would be simpler and more effective to put them in the water supply (see water fluoridation), or the food supply; or if inhalation were necessary, to release them from ground-based vehicles - and have you seen the smoke coming suspiciously out of some cars?
In addition, said Grand Conspiracy would require that all of the world's governments, including the supposedly hostile nations that [insert your favorite government overlords] would have to be in cahoots with, would be agreeing to spray the chemtrails over their own populace, since there is very few national airspaces that do not have at least some aircraft flying to, from, within or over them. Considering the amount of ongoing research on trace components of the atmosphere, the Grand Conspiracy would also have to be suppressing scientific documentation of anomalous chemical presences in the stratosphere, everywhere in the world, without anybody noticing or any authors anywhere crying foul.
But wait! How many international flights go over water where there are no nations, or over the poles where no humans live? Clearly these chemtrails are then responsible for ozone depletion/withdrawal of ice shelfs/reduction of polar bear populations/desalination of the world's oceans/whatever the fuck you want to suggest they are.[citation NOT needed]
All evidence presented by the conspiracy theorists focuses on pictures of the sky. It is all perfectly consistent with contrails. No other evidence such as detection of chemicals or pictures of actual chemical spraying planes or documentation detailing the government's plan has ever been forthcoming. Notably absent are potentially convincing evidence such as spectrographic analyses -- after all, the contents of an aircraft's trail can't be hidden from a spectrograph.
 Discussion tropes
- People who disbelieve in chemtrails "with so much overwhelming evidence" are sheeple
- The "overwhelming evidence" will be skimpy indeed
- "In the 1970s contrails lasted only a few minutes" (this is incorrect)
- Links to YouTube videos where the uploader removes rebuttals against the cranks, followed by Photoshopped videos of "chemtrail vents" on commercial airplanes
- Naturalnews claims that chemtrails, unlike contrails, "linger for hours or whole days." Furthermore, while contrails "are very white and somewhat thinly textured," chemtrails "tend to be thicker and wider than contrails, and their white plumes can be tainted with slight discolorations." Both claims are incorrect
 Fighting the good fight
Websites devoted to raising awareness of chemtrails have failed to ignite the indignation of the masses to the extent that the chemtrails have stopped. So (in typical grand conspiracy fashion) the chemtrail believers claim that the powers that be, rather than revealing their evil purpose by overtly suppressing this knowledge, are covertly suppressing it by recruiting their agents in science and the media to ridicule it as bizarre, kooky and unbelievable.
The best way to promote the cause, of course, is to invoke the admirable hundreds of professional pilots who are forced to release these chemicals into our atmosphere under threat of death. Or not.
 Our sylph allies
Cloudbusting warriors at the (in)famous Whale.to have been pleased to learn that they do not fight the evil government chemtrails alone. They have allies in the clouds! These nebulous allies, the sylphs, help eat up the poisonous "chemsoup", especially when boosted by orgone energy sent up from cloudbusters. You can observe a sylph in action here. Please note exactly how distinguishable the majestic sylph is from, say, a normal wispy cloud (see Pareidolia).
 Chemtrails and geo-engineering
Some chemtrail conspiracy theorists claim that contrails are actually part of a covert geo-engineering scheme either to offset global warming by introducing a substance, generally aluminium, into the atmosphere (this has been discussed with some level of seriousness by geo-engineers) or to poison crops in order to force the populace to purchase seeds from Monsanto. Some cranks have gone so far as to protest geo-engineering conferences.
 See also
- Chemtrails entry in The Skeptic's Dictionary
-  Chemtrails at Psiram
- Contrail Science, a blog debunking many specific reports of chemtrails
- Curious Contrails: Death from the Sky?, Ben Radford, Skeptical Inquirer, Volume 33.2 (March/April 2009)
- "What In The World Are They Spraying On Us?: The Chemtrail/Geo-engineering Cover-up Revealed" (107-minute "documentary"), Truth Media Productions (site), 2010
- What If Chemicals Were Sprayed From Planes, Depleted Cranium
- ↑ See any picture of a crop duster, possibly the closest thing that reality has to a chemtrail or aerobatics aircraft that intentionally lay trails behind them. These do not feature a gap as jet contrails do.
- ↑ B-17
- ↑ Text of HR2977
- ↑ CBS News video: Local news report claims the government is controlling weather using airplanes
- ↑ Clifford Carnicom-Chemtrails
- ↑ 6.0 6.1 Metatech-Chemtrails and cloudbuster tech
- ↑ L T Peçanha and G A Dos Reis - Functional heterogeneity in the process of T lymphocyte activation; all modes of T-cell activation, except PHA-induced mitogenesis, were blocked in a reversible and dose-related manner by Ba2+
- ↑ Barium, Chemtrails & Immunosuppression, Bob Lee, Rense.com
- ↑ http://www.rense.com/1.imagesH/inside11.JPG
- ↑ Boeing.com - 787 Dreamliner testing
- ↑ 11.0 11.1 Contrail science - Contrails, Dark Lines, Black Beams, & “Chemtrails”
- ↑ Atmospheric Optics - Contrail Shadows
- ↑ Space Weather Archive - Tricky Shadows
- ↑ Triple cloud shadow
- ↑ In this particular example, it's possible to see the volumetric shadow extend along the length of the contrail, slightly above it. From another angle, the effect would be to see the shadow grow larger and more apparent.
- ↑ Chemtrail Proof - German Military Exposed.
- ↑ Ron Paul Supporters Spray Vinegar at the Sky to "Kill" Chemtrails!
- ↑ Admittedly, this is not a huge leap for the conspiracy theory crowd to make, which further exemplifies their delusions.
- ↑ Natural News
- ↑ Smattering of Activists Protest Geoengineering, Chemtrails, Science Magazine