I’ve been receiving more e-mails than usual asking about chemtrails, the supposed clandestine spraying of chemicals by jet aircraft, so I thought I would talk a little about the issue.

I was at a townhall meeting a couple years ago, and some biker dude got up and demanded that our congressman do something about chemtrails (the congressman said he had never heard of the issue before). Based upon the level of interest I have seen, there is considerable popular support for the view that chemtrails exist.

First let me say there are such things as “conspiracies”…some people conspire together with all kinds of nefarious motives, both inside and outside government. But not everything that happens in life is a conspiracy.

Jet aircraft at high altitudes produce condensation trails (contrails) which form from water vapor, one by-product of combustion. Some of these clouds can be colorful at sunrise or sunset, just as natural clouds are. Contrail activity has increased dramatically since the 1950s, for the obvious reason that high altitude jet traffic was almost non-existent before that time.

It is indeed possible that the high altitude cirrus clouds formed by jets might have contributed to warming in recent decades due to the greenhouse effect produced by cirrus clouds (thin cirrus reduce outgoing infrared radiation more than they reflect sunlight), although research on this has a large amount of uncertainty.

Now, I suppose it’s possible the Air Force or some other entity has experimented with spraying of chemicals from jets for various purposes. For example, chemical defoliants were sprayed by aircraft from low altitudes during the Vietnam War. But there is no evidence I am aware of that any of the jet contrails you see in the sky on a daily basis is anything other than the passive (and necessary) result of combustion.

Contrails don’t always form behind a jet because sometimes the air is so dry that it absorbs the water vapor from aircraft without condensation taking place. When I was the lead scientist on a microwave radiometer we used to fly over thunderstorms on a modified U2 aircraft, the U2 pilots told us stories of flying spy missions; if the U2 started forming a contrail, they would return home because the aircraft would be too easy to spot from the ground.

I was looking at some of the claimed evidence for chemtrails, for example a 1990 USAF chemistry course outline entitled “Chemtrails”. This indeed seems to establish that the USAF coined the term “chemtrail”, but it was simply a play on “Contrails”, a handbook routinely distributed to cadets. I looked through the chemistry course materials and there was no mention of “chemtrails” in the modern sense of the word.

And graphic artists don’t help when they come up with spoofs, like this one showing airline pilots marching against chemtrails:

Another supposed proof is patents related to spraying of chemicals from aircraft. There is some truth to this claim, because with talk of geoengineering the climate system to offset global warming, there has been considerable interest in spraying a variety of substances into the stratosphere as a way to reflect sunlight in the manner of a large volcanic eruption. As a result, private companies are patenting methods for performing this spraying if it ever becomes a funded project.

But the claim that daily, routine jet traffic involves the secret spraying of chemicals for population control by the government, or to keep us sick to support the pharmaceutical industry, etc., is pretty wild. There is much more information debunking various chemtrail claims at a website called contrailscience.com.

So how do flying saucers fit into this? Well, it was pointed out that a patent for a chemtrail (or any other) device does not mean that a device has ever been developed…or that it would even work. I’d be interested in hearing some physicists’ opinions on the patent for a Space vehicle propelled by the pressure of inflationary vacuum state:

But, I suppose conspiracy is in the eye of the beholder, and I’m sure someone in comments below will claim I am part of the conspiracy that perpetuates the “myth” of the greenhouse effect. Oh, well.