Talk:Contrail

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And of just what are these two photos? 142.177.126.57 16:52, 19 Sep 2004 (UTC)

And just what do we see here?! Clearly, some person of dubious morality is arranging the spraying of EVIL ™ into our skies.

Beyond the temperature aspect, didn't post-9/11 studies indicate contrails account for something huge, like up to 20% of US cloud cover? Chris Rodgers 00:59, 24 Dec 2004 (UTC)

About that page above, with the two photos, I saw something just like that outside my window today. At first, there was a single long contrail stretching across the sky, but then the wind must have blown on it a lot, because it separated into two distinct parts. One part had moved a little bit to the East, and the other half had moved a whole lot further. You can see in the bottom photo that the chunk of contrail that's missing is actually at the bottom of the picture, just that it's been mostly cropped out. The plane obviously didn't stop spraying anything, just a strange current of air blew that particular part of the cloud away from the rest. In fact, seeing this interesting phenomenon is what brought me to this page in the first place, I hope my explanation of what's going on in those deceptive photos is enough to put some fears to rest. —Preceding unsigned comment added by 63.64.64.194 (talk) 00:45, 12 January 2008 (UTC)

Contents

[edit] Conspiracy theory

I removed the following from the article as (1) it's insane; (2) it is a direct cut-and-paste from the Straightdope article and hence a potential copyright problem. -- Blorg 10:57, 30 Jan 2005 (UTC)

A conspiracy theory postulates that contrails are chemical experiments conducted by the government:
Some tell tales of mysterious white tanker planes, a counterpart to the black helicopters of paranoid legend, crisscrossing the country spraying "chemtrail" that make people sick. Often the chemtrails form an X, which is "read by satellites to track dispersal patterns," we learn. In many cases the contrails are accompanied by a cobweblike cloud of "angel hair" filaments descending from the sky. Other times clear or brown Jell-O-like goop spatters the landscape. Some think the goop and the filaments result from improperly adjusted spray nozzles on the mysterious aircraft. [1]

EDIT: I didn't realise that the above was a direct quote. In any case, I don't really think Wikipedia should be giving space to any old insane conspiracy theory (we could add a lot of insane material to a lot of articles if that were the case). As Cecil says on Straight Dope: "Are these people crazy? Of course they're crazy." (I've left in the more reasonable part about the climate change.) -- Blorg 11:03, 30 Jan 2005 (UTC)

The conspiracy theory is adequately—some say far, far more than adequately—covered at Chemtrail. (I personally think it's nutcase stuff but a fairly notable theory of its kind, and I tried to keep the article neutral). It is just barely possible that the Contrail article ought make a brief mention and link to Chemtrail, e.g. line in a "see also" section saying:
    • Chemtrail, a conspiracy theory that some contrails are caused by the high-altitude spraying of unknown chemicals by unknown agencies for unknown purposes,"

or perhaps a line at the top,

For the conspiracy theory see Chemtrail

I won't do this myself because people are already saying the Chemtrail article gives too much credence to the conspiracy theorists. Dpbsmith (talk) 12:29, 30 Jan 2005 (UTC)

A 'see also' reference like you suggest would be fine, I think. -- Blorg 12:15, 1 Feb 2005 (UTC)

[edit] Chemtrails don't exist. People who believe in them DO exist.

I personally think chemtrails are nutcase stuff. Nevertheless, the existence of a significant number of people who believe in them is a verifiable fact, and there are enough of them to make it important. Therefore, it is perfectly appropriate for us to have an article on Chemtrail theory. And it since chemtrails happen to look like contrails (—happen to look exactly like contrails—because they are contrails—) the link is perfectly appropriate. Dpbsmith (talk)

This argument extends to the inclusion of references to anything at all in any other article. What constitutes "a significant number" of people? There are probably as many people who believe that contrails are fairy candyfloss as believe in the conspiracy nonsense: should the article also reflect their 'beliefs'?

  • I am not aware of any such people. If someone were to produce a good verifiable reference, like a newspaper article, that says that there really is a substantial group of people holding that belief, then of course it should. We have an article on Hollow earth and we have many articles on pseudoscientific topics. The way you sort all these things out is by producing explicit source citations. The moon is made of green cheese? Fine, as long as I know who says so and am given enough information so I can judge their credibility. Dpbsmith (talk) 16:05, 3 September 2005 (UTC)

The point of this article (and any other) is to *convey facts*, not to be a representative survey of 'beliefs'. That's why this site claims to be an encyclopaedia and not a tabloid newspaper.

I see from this article's history that repeated attempts to remove the conspiracy nonsense have been sabotaged by editors in the name of "inclusiveness".

The next time the conspiracy reference is removed, *please do not reinsert it*.

People who want to improve this article, in terms of enhancing the quality of the material it contains and its relevance to the article's title (NB. Contrails, not Chemtrails) should not have to battle against ridiculous editors that want to appease every viewpoint.

P.S.

"Perhaps the easiest way to make your writing more encyclopedic is to write about what people believe, rather than what is so. If this strikes you as somehow subjectivist or collectivist or imperialist, then ask me about it, because I think that you are just mistaken. What people believe is a matter of objective fact, and we can present that quite easily from the neutral point of view."

Dpbsmith (talk) 11:17, 3 September 2005 (UTC)

I have read this and disagree with it.

Well, be careful about acting on that disagreement, because Jimbo Wales calls adherence to WP:NPOV "absolute and non-negotiable."

How about a compromise? The text referencing the conspiracy theory does not currently reflect the fact that more people disbelieve the conspiracy theory than accept it.

As this article is so eager to reflect 'opinions', there should be some mention of the majority opinion and the conspiracy theory should be described as "discredited" or "derided".

Is this acceptable?

P.S.

  • I can't speak for others. It's OK by me. My $0.02 on the language: I'd personally prefer that it be characterized as "not generally accepted" or "not widely accepted." I think it's an objective fact that has been "derided." I'm not sure anyone has really bothered to "discredit" it, as it would first have to have been "credited." Word it as you like; I won't revert. Dpbsmith (talk) 15:41, 3 September 2005 (UTC)
  • I don't really care how it's worded so long as it's mentioned. Dpbsmith's wording above is fine, but the current wording looks to be adequate to me also. "Conspiracy theory" implies it's believed by "fantasists and the deranged" all by itself. —Cryptic (talk) 15:48, 3 September 2005 (UTC)
    • Since I was actually looking for that conspiracy article, I thought the natural place it would have been linked to, is from here. Not linking to is would not be adhering to NPOV, so, after another 25min of searching for it, I added it back. Sorry if it ruffs feathers, but it should at least be in the See Also sect. If you feel that Chemtrail conspiracy theory is unworthy, please feel free to nominate it for AfD. And as for describing the theory as "discredited" "derided" "not generally accepted" or "not widely accepted", that is not within the realm of this article to do so, that should be dealt with on the theory's Article, not here. Let the reader make up their own mind, that is the purpose of an encyclopedia. Exit2DOS2000•T•C• 12:03, 22 March 2008 (UTC)

[edit] Droplets?

Does the water in jet exhaust always condense to droplets, or does it sometimes desublimate directly to ice crystals?

[edit] Desublimation/Deposition

Deposition and the literal argument for 'subtrails' (sublimation+trails), seem to be pure concoction.usga.gov asserts that "The opposite of sublimation is deposition". Googling "deposition of water" and "desublimation of water" for 21,000 results and 10 results, respectively. Subtrails might be an article about an obscure mathematical concept, however. Google subtrails for 304 results. http://ga.water.usgs.gov/edu/watercyclesublimation.html Qe2eqe 16:31, 7 April 2007 (UTC)


...trying to assert a neologism as the correct term is definitely out... William M. Connolley 20:32, 28 September 2005 (UTC).

[edit] Contribution to the Greenhouse Effect

The article mentions that contrails contribute to global dimming and thus counteract global warming, but it fails to point out that the cirrus clouds that form from contrails also contribute to the greenhouse effect and thus warm the earth. The warming effect does not seem to be insignificant either; it may well outweigh the cooling effect. A 2004 NASA press release stated that "...increased cirrus coverage, attributable to air traffic, could account for nearly all of the warming observed over the United States for nearly 20 years starting in 1975..." (Clouds Caused By Aircraft Exhaust May Warm The U.S. Climate) In its current state, this article seems to perpetuate a very inaccurate image of the environmental effects of contrails. Kghhd 06:07, 10 October 2005 (UTC)

[edit] NASA Experiment

Unless sources are introduced regarding NASA experimentation, I'm planning to remove this whole section as unsourced rumor. Jpers36 19:24, 21 December 2005 (UTC)

Done. Jpers36 13:50, 23 December 2005 (UTC)

[edit] Contrail creation comments

A few observations regarding the section titled Contrail creation

  1. The final paragraph assigns names to the two types of contrails. It says that (1) is called exhuast contrails and (2) is called wingtip contrails. These titles can be introduced above, with the descriptions of the two types
  2. The two paragraphs of (1) are trying to describe the same thing, but they are inconsistent. They both describe the composition of the exhaust, and how it becomes visible. However, the first paragraph says the visible material is water droplets, while the second says it is ice droplets. I suggest that these two paragraphs be combined into a single consistent paragraph.
  3. As this section not only explains the creation of contrails, but also their classification, perhaps its title should be changed to accomodate this more general function.

--Epl 06:19, 9 January 2006 (UTC)

[edit] Contrail and supersonic aircraft

Does a supersonic aircraft produce a visible contrail? Dart evader 10:49, 17 February 2006 (UTC)

[edit] Quoted in newspaper

Some people theorize vapour trails are chemical or biological agents being secretly released in the air, says Wikipedia, an Internet encyclopedia. Chemtrails refer to systematic, high-altitude dumping of unknown substances for some undisclosed purpose. Theories proposed for their purpose include atmospheric and weather modification, biological warfare, mind control and military uses. -- Kerry Hall's "Contrails: a problem all their own", Parksville Qualicum News

When I thanked the newspaper for referencing us in the article, the reporter replied that Phil Austin, at cloud physicist at University of British Columbia (who was quoted in the story), thought this was a good explaination of the topic. Thumbs up, everyone who worked on this! -- Zanimum 17:12, 2 August 2006 (UTC)


[edit] Question about formation of contrails and wing design

I note this sentence here: "The wings of an airplane cause a drop in air pressure in the vicinity of the wing (this is partly what allows a plane to fly). This drop in air pressure brings with it a drop in temperature, which can cause water to condense out of the air and form a contrail." Would this imply that it is possible to design aircraft to reduce the production of contrails? (Sucn a principle would have both commercial and military utility .) Hi There 17:34, 2 August 2006 (UTC)

[edit] Ectoplasm example photo

The recent Blue Angels show in San Francisco provided some nice examples of the ectoplasm effect described on this page. I'm wiki-challenged or I'd try to add one to the main page; here it is on Flickr:

http://flickr.com/photos/fitzhugh/263984025/

[edit] Conditions for formation

I couldn't find this in the article, but maybe I just didn't have the patience to read it well enough: why do contrails form in some places and not in others? I've been to places where planes NEVER form contrails. I suppose it's a weather thing -- the place was in a [sub-]tropical climate. --Cotoco 04:56, 15 October 2006 (UTC)

[edit] Ectoplasm?

At lower altitudes, this phenomenon is also known as "ectoplasm."

I have never come across this term to do with the formation of vapour over the wing or in the wingtip vortices before, either in technical or non-technical literature. The only references a Google search returns for it appear to be derived from this article. Unless someone can provide a source for it, I propose that it be removed from this article, and from the disambiguation page for ectoplasm. Nick Moss 11:26, 16 June 2007 (UTC)

[edit] Another contrails and climate reference

If someone wants another reference for the "Contrails and climate" section, the 2004 Minnis, et.al paper "Contrails, Cirrus Trends, and Climate" can be found here, and its results are briefly given here. -- HiEv 15:23, 15 November 2007 (UTC)


It should be pointed out that "vapor trail" is a misnomer. What is seen in the contrail is water, not water vapor. Nearly all in aviation know this, and don't say "vapor trail." Water in its vapor form is not visible. Many who have taken a physics or chemistry course know this. —Preceding unsigned comment added by Bethpage89 (talk • contribs) 18:26, 17 January 2008 (UTC)

Commercial airliners do not leave permanent trails and ice crystals do not survive in the hot sun for hours.Insighttoo (talk) 03:51, 3 March 2008 (UTC)