Contrail vs Chemtrail ????
It isn't all that difficult to remember our clear blue skies prior to the mid 1990s. It isn't all that difficult to remember that occasionally jet aircraft would display a "Contrail" that would dissipate rapidly as the airplane continued on its journey. But what I have seen behind aircraft since the mid 1990s seems totally different.
Wikipedia defines "Contrails" in the following manner. As follows ...
Condensation from engine exhaust
The main products of hydrocarbon fuel combustion are carbon dioxide and water vapour. At high altitudes this water vapour emerges into a cold environment, and the local increase in water vapour can raise the relative humidity of the air past saturation point. The vapour then condenses into tiny water droplets which freeze if the temperature is low enough. These millions of tiny water droplets and/or ice crystals form the contrails. The time taken for the vapour to cool enough to condense accounts for the contrail forming some way behind the aircraft's engines. At high altitudes, supercooled water vapour requires a trigger to encourage deposition or condensation. The exhaust particles in the aircraft's exhaust act as this trigger, causing the trapped vapour to rapidly condense. Exhaust contrails usually occur above 8,000 m (26,000 ft), and only if the temperature there is below −40 °C (−40 °F)
If a "Contrail" is the byproduct of hydrocarbon fuel combustion at high altitudes ... it is difficult to understand how that process could be any different today than it was prior to the mid 1990s ... unless these trails are chemically based rather than water vapor based. Chemically based trails are being referred to as "Chemtrails".
Wikipedia refers "Chemtrails" as one of those "Conspiracy theories". As follows ...
The chemtrail conspiracy theory holds that some trails left by aircraft are actually chemical or biological agents deliberately sprayed at high altitudes for purposes undisclosed to the general public in clandestine programs directed by government officials. This theory is not accepted by the scientific community, which states that they are just normal contrails, and that there is no scientific evidence supporting the chemtrail theory.
As a result of the popularity of the conspiracy theory, official agencies have received thousands of complaints from people who have demanded an explanation. The existence of chemtrails has been repeatedly denied by scientists around the world, who say the trails are normal contrails. The United States Air Force states 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 United Kingdom's Department for Environment, Food and Rural Affairs has stated that chemtrails are not scientifically recognized phenomena. The Canadian Leader of the Government in the House of Commons has rejected the idea of chemtrails as being a "popularised expression", adding that "there is no scientific evidence to support their existence."
The term chemtrail is derived from "chemical trail", in the similar fashion that contrail is a portmanteau of condensation trail. It does not refer to other forms of aerial spraying such as crop dusting, cloud seeding, skywriting, 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 characteristic sky tracks. Supporters of this conspiracy theory speculate that the purpose of the chemical release may be for solar radiation management, population control, weather control, or biological warfare/chemical warfare and claim that these trails are causing respiratory illnesses and other health problems.
Clearly something has changed regarding the exhaust coming from high flying jet aircraft since the mid 1990s and this is where it gets interesting. The supposed claims of the scientists and government agencies fits quire nicely into something called "plausible deniability". Which, oddly enough, is a well known government ploy used to disenfranchise any nay-sayers.
Wikipedia also defines "Plausible deniability". As follows ...
Plausible deniability is a term coined by the CIA during the Kennedy administration to describe the withholding of information from senior officials in order to protect them from repercussions in the event that illegal or unpopular activities by the CIA became public knowledge.
The term most often refers to the denial of blame in (formal or informal) chains of command, where senior figures assign responsibility to the lower ranks, and records of instructions given do not exist or are inaccessible, meaning independent confirmation of responsibility for the action is nearly impossible. In the case that illegal or otherwise disreputable and unpopular activities become public, high-ranking officials may deny any awareness of such act or any connection to the agents used to carry out such acts. It typically implies forethought, such as intentionally setting up the conditions to plausibly avoid responsibility for one's (future) actions or knowledge.
In politics and espionage, deniability refers to the ability of a "powerful player" or intelligence agency to avoid "blowback" by secretly arranging for an action to be taken on their behalf by a third party ostensibly unconnected with the major player. In political campaigns, plausible deniability enables candidates to stay "clean" and denounce third-party advertisements that use unethical approaches or potentially libellous innuendo.
More generally, "plausible deniability" can also apply to any act that leaves little or no evidence of wrongdoing or abuse. Examples of this are the use of electric shock, waterboarding or pain-compliance holds as a means of torture or punishment, leaving few or no tangible signs that the abuse ever took place.
Plausible deniability is also a legal concept. It refers to lack of evidence proving an allegation. Standards of proof vary in civil and criminal cases. In civil cases, the standard of proof is "preponderance of the evidence" whereas in a criminal matter, the standard is "beyond a reasonable doubt." If your opponent lacks incontrovertible proof (evidence) of their allegation, you can "plausibly deny" the allegation even though it may be true.
So its time for you to do your own research. Take a look at ... http://www.youtube.com/watch?v=jf0khstYDLA
The obvious question is, "Just what is in that stuff they are spewing from the back of many high flying aircraft?"
I'm open to comments offered in a constructive way.