Chemtrails

Chemtrails are said to be the trails left by aircraft when the conditions are right. The air passing the wing is suddenly compressed and decompressed. As result moisture in the air condenses. It is then visible. That is the normal contrail. But people are worrying about chemtrails which, they think are being used to shower us with chemicals. The evidence is out there. It proves that people are worrying. Whether is proves there is a problem is another matter entirely.  A good start is to ask why they would do it that way in the first place.

The first link is to a doubter. I suspect that they are right.

New Mexicans for Science and Reason
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Perhaps you've come across the dire warnings on the Internet: "HIGH ALERT!! REPORTS ARE COMING FROM EVERYWHERE PEOPLE!! RED ALERT ** HOSPITALS JAMMED AS BANNED PESTICIDE IS SPRAYED FROM THE SKIES (formerly on http://home.earthlink.net/~ravenlmr/index2.htm.)

What's all this about, you ask? It's called "Chemtrails," a purported government program to deliver poisonous or mind-controlling substances to the general population by spraying from airplanes.
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A calm look at the evidence tends to be persuasive.

 

A Pilot's View Of Chemtrails
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First, let’s establish how a normal contrail is formed.  When burned, fuel containing hydrogen is combined with oxygen in the air to form water vapor, among other byproducts.  Under certain conditions, that vapor will condense to form a visible trail – an artificial cloud, for all intents and purposes.  Because the high temperature of the exhaust gas keeps the water in a vapor state until it has a chance to mix with the colder surrounding air, this artificial cloud will always form some distance behind the aircraft, rather than directly aft of the engines.  If atmospheric conditions support a “persistent” contrail, it will most likely become more visible and spread to a more natural cloud-like state with distance from the aircraft.

If an aircraft were spraying some form of liquid or powdered solid, such as bacterial agents or aluminum particulates as suggested by many theorists, it should be most visible directly behind the trailing edge of the wing (or wherever the nozzles may be located), becoming less visible as it dissipates in the atmosphere in the wake of the plane.  This is exactly what you would observe when watching a crop duster.  Yet, in every photo of an aircraft producing a “chemtrail” I have seen, the opposite is true.  They all look like normal contrails.

Having said that, it is possible to make a sprayed agent behave as a contrail.  In the case of a liquid, it would have to be heated to the point of vaporization, so that the vapor would re-condense in a manner consistent with a normal contrail – some distance behind the aircraft.
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He gives two ways of forming contrails. He also seems sensible.

 

Chemtrail conspiracy theory ex Wiki
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The chemtrail conspiracy theory holds that some contrails are actually chemicals or biological agents deliberately sprayed at high altitudes for a purpose undisclosed to the general public. Versions of the chemtrail conspiracy theory circulating on the internet and radio talk shows theorize that the activity is directed by government officials. As a result, federal agencies have received thousands of complaints from people who have demanded an explanation. The existence of chemtrails has been repeatedly denied by government agencies and scientists around the world.

The United States 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 British Department for Environment, Food and Rural Affairs has stated that chemtrails "are not scientifically recognised phenomena". The Canadian Leader of the Government in the House of Commons has stated that "The term 'chemtrails' is a popularized expression, and there is no scientific evidence to support their existence."

The term chemtrail is derived from "chemical trail" in the similar fashion that contrail is an abbreviation for condensation trail. It 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 for global dimming, population control, weather control, or biowarfare [ see under - Editor ] and claim that these trails are causing respiratory illnesses and other health problems.
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The Wiki is not buying into this one either.

 

Aum Shinrikyo
Went in for biological war in Tokyo. It was Japanese, rich, determined to destroy and surprisingly ineffective. It is worth a look for a balanced view of how practical these things are.

 

Biowarfare
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Biological warfare (BW), also known as germ warfare, is the use of pathogens such as viruses, bacteria, other disease-causing biological agents, or the toxins produced by them as biological weapons (or bioweapons).

There is a clear overlap between biological warfare and chemical warfare, as the use of toxins produced by living organisms is considered under the provisions of both the Biological and Toxin Weapons Convention and the Chemical Weapons Convention. Toxins of organic origin are often called "midspectrum agents".

A biological weapon may be intended to kill, incapacitate, or seriously impair a person, group of people, or even an entire population. It may also be defined as the material or defense against such employment.

Biological warfare is a military technique that can be used by nation-states or non-national groups. In the latter case, or if a nation-state uses it clandestinely, it may also be considered bioterrorism.
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Chemtrails as Biowarfare? Conceivable but decidedly unproven.