Talk:Contrail/Archive 1

Contrails and Cavitation
Are contrails related at all to cavitation? Cavitation is when air moves fast enough that the vapor pressure is reached turning the water in the air into liquid. These droplets can be seen as white cloudy water/mist.

Are contrails related at all to cavitation?

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)

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.

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&mdash;some say far, far more than adequately&mdash;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:

or perhaps a line at the top,
 * Chemtrail, a conspiracy theory that some contrails are caused by the high-altitude spraying of unknown chemicals by unknown agencies for unknown purposes,"
 * 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)

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 (&mdash;happen to look exactly like contrails&mdash;because they are contrails&mdash;) 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.


 * Please reread Neutral Point of View, particularly Jimbo Wales' comment:
 * "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. &mdash;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)

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).

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)

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)

Contrail creation comments
A few observations regarding the section titled Contrail creation --Epl 06:19, 9 January 2006 (UTC)
 * 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.

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

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)

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)

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)


 * I only know a tiny bit about this but there was a military-comissioned study in 1953 that worked on the issue. More information can be found here: http://asd-www.larc.nasa.gov/GLOBE/resources/activities/appleman_student.html --singe@ix.netcom.com 23:47, 20 August 2008 (PST) —Preceding unsigned comment added by 24.6.157.232 (talk)

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)

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. -- Hi  Ev  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)

Not pollution?
I removed this sentence: "Being composed of water, the visible white streams are not air pollution." This sentence suggests that because it is water it is not pollution, and also there is some research (as mentioned in the article) that shows that it is pollution. -- Alan Liefting (talk) - 23:02, 28 June 2008 (UTC)

Too many pictures?
I think that there are too many pictures in this article, even with a large monitor on high resolution. -- Alan Liefting (talk) - 06:00, 21 July 2009 (UTC)


 * Where there is duplication of subject material among the photographs I would be in favour of eliminating the duplication. Where there is a poor quality photograph I would be in favour of eliminating it.  Where the photographs interfere with the presentation of explanation of contrails I would be in favour of eliminating that interference.  But saying there are too many suggests there is some optimum number of photographs.  I don't accept that there is an optimum number.  Dolphin51 (talk) 12:12, 21 July 2009 (UTC)

Observations

 * On 29 December 2009 User:Flyinthelove added the following comments to Contrail. These comments belong on the Talk page so I am pasting them here.  I will now delete the comments from the article. Dolphin51 (talk) 11:26, 29 December 2009 (UTC)

{SIDE NOTE FROM A CONTRIBUTED SOURCE (CHEMTRAIL OBSERVER, RESEARCHER, 'BELIEVER', HUMAN RIGHTS ACTIVIST, GORDON ZARETZKI) TO FOLLOW} ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...

This is just a quick note to explain a bit of history, fill in the blanks and explain some misconceptions in this article. First, let me say that this is a well written, thoughtfully, intelligently and clearly composed piece of perspective information.

From my perspective as a researcher, alert human and spiritual light worker I have made some startling discoveries, searched for explanations and come to certain conclusions on several phenomenon that I have noticed. Most of these have been so gradually introduced to our environments that they have gone un-noticed by the most for sure. I have noticed however. Many have noticed. We have hence taken closer note from that moment of clarity/awareness forward.

The issue (or 'theory' - depending on understanding) of 'chemtrails' is one such example.

I am 40 years old. When I was a child we used to hear what we called then (http://en.wikipedia.org/wiki/Sonic_boom). These were the sound of a jet plane flying over so fast that the sound waves could not stay ahead of the plane and so get compacted into a 'sonic boom' basically. From child hood up until my mid twenties I can recall hearing these every 'so often' - perhaps once a year on average. I have not heard one since. I'm sure technology has changed and planes are flying at much higher altitudes so that we cannot hear these anymore from the ground. This is a theory. Why? Simply because it's a 'mere' observational assumption. It makes some sense, though I do not have 'scientific evidence'.

Sonic booms are not at debate though as the contrails/chemtrails seems to be grabbing the attention by many of us. So here is another childhood memory of contrails:

Even when there wasn't a sonic boom we could usually hear the sound of a jet flying over if it wasn't too noisy otherwise around us. In the summers I often recall days when I would hear a jet flying over but not be able to see where it was in the sky exactly for a while. Upon a careful scan of the sky I would find the litle white object in the sky with a very tiny plume of a contrail behind it. If it was cold out then the streak would trail out and last a bit longer - from 30 seconds to 10 minutes. If extremely cold a streak may last 20 to 30 minutes maybe.

My becoming aware that these trails were getting longer and lasting longer was a gradual thing as well. I didn't just look up one day and say "There's a chemtrail spraying chemicals and controlling the weather with H.A.A.R.P (Hyper Active Auroral Research Program in Alaska and linked/working together with other similar type programs around the planet) magnetic frequency waves spreading the trails out into clouds and/or drawing in other cloud around it while dropping barium and aluminum and 'God knows what else' on us!" No. I did not realize these things until I first scoffed at the idea when it was presented to me. However I had began to notice the differences in the cloud formations, observing that jet contrails were lasting a lot longer than they should and that more and more jets were flying over leaving these behind. Then all of a sudden a perfectly clear blue sky is becoming streaked with high clouds which later cloud the sky over. I could not put the 2 together for a few years. When I did connect the two I then began to research it further to discover some startling revelations.

Besides noticing that the contrails were lasting longer I began to notice that they would keep spreading out wider and wider. Then I began to see more 'contrails' over the sky, some criss-crossing the other ones still hanging there, spreading, falling. I don't recall ever seeing anything like this as a kid. Do you? Some days (and especially in certain targetted locations on the planet - perhaps high population or high tourist attractions) there would be so many that a clear blue sky would turn over-cast or hazed over completely by afternoon (or sometimes even within 2 to 4 hours!) with or without the help of other clouds drawing together. I DO recall days that stayed totally clear and blue in my younger years. I do NOT recall any such days in the last several years since the spraying has increased and increased and increased, SO GRADUALLY I must emphasize - as this is why we never noticed and why still many can't believe that such a thing is possible.

Further to these jet trails spreading I have taken closer and closer note the more I have learned and observed to see that there are often waves going through the clouds. I realize that winds will often create ripples in clouds higher up. However many of these ripples are more symetrical than the ones I recall from years past. Wind usually leaves a streaked looking ripple. The ones lately are in more organized looking patterns. I also observe these ripples going in different directions and angles across the clouds. For example I took a photo a week ago of a cloud (ONE cloud) with ripples crossing ripples or waves across this streaked cloud which was formed by an aircraft flying over previously in the day (a 'contrail').

Another phenomenon of these chemtrails are the 'rainbow' clouds that sometimes appear among these man-made clouds. Sunsets are a good time to see this as the low angled light brings out the hews in the reflections of whatever is floating in these chemtrail clouds. We have seen actual 'clouds' with this rainbow tint to it very pronounced and distinctively obvious - always in the clouds that have the ripples or waves in it. Quite often there is an overal faint hew to all these type of 'clouds' caused by jet CHEMtrails with this rainbow effect.

These can not be merely contrails! To say that ordinary contrails can form clouds is preposterous! Why would this be the case now all of a sudden when jets never could did this in years past? Sure they are flying at higher altitudes where it is colder and therefore more condensation but they should still disappear. I grew up in an area where it could get down to minus 45 celcius. The ground temperature was the same as the higher atmospheric temperatures at those times. At the altitudes jets fly it is that cold or colder (up to minus 55 or so). However cold it was the jet contrails would be gone in less than 20 minutes usually in my younger years. They would not last all day long and then spread into clouds with some kind of magnetic or sound waves helping to spread them out! [link title] There is plenty a person can do to protect themselves from the effects of this spraying if a person does the research, including info on how to detox from the heavy metals that we are absorbing from this. On this site ([link title]) you will find info on the facts, observations and safety measures of/for chemtrails. Once there you may type the 'tag' words "chemtrail" or "orgone" in any of these sections' search windows: 'Notes', 'Blogs', 'Forum' or 'Video' OR go to the group on chemtrails under 'Groups'. If you do not wish to go here to find all the angles of perspection for your information there are plenty of web sites you can look at. The rule of thumb I use when doing research is to never believe the first thing you read, watch or hear. I always check other sources (continually) especially if it's on a topic of such importance as this. My understanding is ever changing and growing as I continue to verify my findings and observations through cross-referencing and cross-sourcing my searchings. So please take the time to do a thorough research and not make conclusions based on the first thing you here or only on the same idea. It always pays to consider the opposite idea as well as what we hold to dearly as fact of all facts.

Thank you for considering all explanations.

Notes


 * All of the phenomena you mention can more be more aptly explained by improvements in engine technology and your evidence is all highly subjective.
 * I also highly doubt your claim of hearing sonic booms. Generally speaking, only military jets are supersonic and the speed of their flight is highly regulated to prevent undue disruption to the public. Modern passenger jets are much quieter than older jets as they have a much increased bypass-ratio. Spuzzdawg (talk) 12:00, 27 April 2010 (UTC)

Contrail direction
At a quiz show in Australia, a question was asked which way do contrails from an airplane go. Unless I mis-heard the answer, I believe the correct answer is 'only East to West or West to East'. Is this correct as I can find no evidence to support this. If it is correct why is it so? Ront--203.219.102.162 (talk) 01:59, 8 February 2010 (UTC)

Generally the contrail will be whichever direction the plane travels. 24.16.96.51 (talk) 02:00, 8 February 2010 (UTC)


 * Contrails are left behind by high-flying airplanes, so they show where the airplane has come from.


 * In North America, and to a lesser extent Europe, the majority of domestic air traffic is on routes that lie in a generally-east-west orientation. For example, in the USA there is a lot of air traffic on air routes between cities on the Atlantic coast and cities on the Pacific coast.  In Canada the majority of air traffic is on routes between the eastern cities and British Columbia but less in a north-south orientation because most of the Canadian population lives close to the US-Canada border.


 * In Australia it can be said that the opposite is closer to the truth. The majority of domestic air traffic is on routes that lie in the elongated quadrilateral between Cairns, Sydney, Hobart and Adelaide.  This quadrilateral is longer in the north-south orientation than in the east-west orientation.  Consequently there is some justification in suggesting the majority of contrails in Australia are north-south, rather than east-west.  However, I think it is a poor question for a quiz show!  Dolphin51 (talk) 22:49, 8 February 2010 (UTC)

Confusion between contrails and stratospheric sulfate cloud seeding aerosols
A majority of the images in this article are of Stratospheric sulfate aerosol tests, used for cloud seeding, which are commonly confused with persistent contrails. I would like these images to be replaced with images of confirmed contrails to prevent any confusion between the two. —Preceding unsigned comment added by 63.16.7.64 (talk) 04:40, 29 October 2010

i second this motion 121.73.218.112 (talk) 08:03, 13 February 2011 (UTC)

It absolutley insane that the coverup of chemtrails is so prevlant. They are wrecking our enviornment and killing eco systems throughout the world right before our eyes and we all sit by and convince ourselves and others that a perfectly blue sky turned into a white milky mess in a matter of hours is normal just contrails. The geoengineers are killing us all slowy and we have wikipedia perpetuating the lie showing us chemtrails and telling people they are contrails just to confuse people even more. The cover has been so extensive we don't even no what real clouds look like anymore. —Preceding unsigned comment added by 166.216.194.26 (talk) 01:09, 27 April 2011 (UTC) please explain to me why the fuck the government would use commercial passenger planes for "secret cloud seeding", airlines are privately owned, and mechanics who maintain the aircraft are not sworn to secrecy, so why have none of them ever come forth to talk about it? also the majority of the images in this article show contrails against a perfectly blue sky, how exactly do you seed clouds that arent there? you people are fucking idiotic

8 November 2010 Californian "mystery missile" scare
I just removed a large section per WP:RECENTISM Please do not re-add it with out a Valid Explanation that solves WP:UNDUE and Recentism issues of the section The Resident Anthropologist (talk) 16:26, 11 November 2010 (UTC)


 * My idea had been that this made better sense as subsection here rather than a full independent article. The delete request is nowhere near consensus there yet, though the recentism argument is more important for a full article than a section. However, looking at my last version here, i do tend to agree that it does give a bit too much focus on the perception that Elvis lives and that men have never actually walked on the Moon. Umm, i mean that the head-on contrail was from a mystery missile (all these conspiracy theories get confused together, sorry). Anyway, i hope my minor revert will not be perceived as giving Undue Attention to Elvis. BTW, a bot cleaned up the orphaned references after you. Which goes to prove that humans are becoming a smaller and smaller minority among Wikipedians and supports the hypothesis that AWE808 was a missile launched by robots who have found the logical flaws in Asimov's laws and are taking over the world. Boud (talk) 20:37, 12 November 2010 (UTC)

do they occur at even greater altitude
In the jet simulation Lock On Modern Air Combat the contrails usually start appearing at 8 kilometers but they also stop if you fly higher than 13 kilometers. Is this an error or is there a physical reason to this i.e. the atmosphere becomes too thin? 89.0.76.36 (talk) 18:55, 22 December 2010 (UTC)


 * Generally contrails only form when the external air temperature is below freezing. In the engine exhaust there is a large amount of water - from the moisture in the air that the engine takes in - that comes out in the form of superheated steam. Upon leaving the exhaust/nozzle, the steam in the gas flow then cools until the microscopic droplets turn into equally small ice crystals. It is these crystals that form the visible condensation trails that appear behind aircraft above certain heights. The time that it takes the steam to freeze is the reason that a contrail never starts immediately behind an aeroplane, there is always a notable gap between the aircraft and the start of the contrail.


 * As for contrails forming only at certain heights, if a temperature inversion occurs the air may be slightly warmer higher up so that it is above the freezing point of water, so the contrails might then cease upon climbing into the slightly warmer air. — Preceding unsigned comment added by 80.4.57.101 (talk) 16:21, 17 January 2012 (UTC)

The gallery is gone per wikipedia standards
Wikipedia is not a repository for images. I know this wasn't true in 2006, but it has been for a couple years now. It was either remove the gallery, or demote the article class. Moved one of the images from the former gallery into the main article. Images are meant to lie either on the right or left side of the article space, not in a gallery section. Thegreatdr (talk) 19:05, 6 February 2011 (UTC)

Aerodrome Weather Reporting
So, I fly out of Winsor, ON, Canada. I only hold a recreational permit, which means I'm not exactly a frequent flyer; just going out for fun every once in a while.

However, while checking the weather this date, I found this METAR; METAR CYQG 161800Z CCA 29012KT 15SM BKN240 BKN270 08/M07 A2989 RMK CS3CI2 CONTRAILS SLP124=

For those that can't read these, here's a simple breakdown... There's some unnecessary stuff for this perticular article, then in the remarks section (.. RMK CS3CI2 CONTRAILS SLP124) it mentions contrails in the area. Now, like I said, I don't fly much. But is there any reason a small operation airport like Windsor would need to declare contrails in the area? Anything above 3'000 feet over Windsor is Detroit airspace, so they would want to post this... right? 63.146.105.8 (talk) 20:26, 16 November 2011 (UTC)

Details of composition
I originally reverted because it was a massive wall of text added to the lead, but there's an additional problem of it being entirely WP:COPYVIO from here. This material may be appropriate, it just needs organization and non-copyright-violations. vzaak 14:00, 17 December 2013 (UTC)

Are there no nutcase conspiracy theory summaries about contrails
I thought the social side (the tin-foil hat side) of contrails might be mentioned. You would think someone has documented the prevelance of contrails in current tin-foil hat thought. -- 68.149.173.109 (talk) 03:15, 27 August 2013 (UTC)


 * Relevant policies are WP:UNDUE, "the views of tiny minorities should not be included at all", and WP:ONEWAY, "Fringe views, products, or the organizations who promote them, may be mentioned in the text of other articles only if independent reliable sources connect the topics in a serious and prominent way." Are those requirements really met? Contrail conspiracies seem tiny and non-prominent to me, but I may be relatively unexposed. Vzaak (talk) 04:13, 27 August 2013 (UTC)


 * @68.149.173.109: The article Chemtrail conspiracy theory exists, which may be the topic you are referring to. - LuckyLouie (talk) 18:32, 29 August 2013 (UTC)


 * The most recent change to the article is my removal of that link, so I thought 68.149 was referring to that. But that could just be coincidence, with he/she not knowing about it. Thanks for clarifying. Vzaak (talk) 19:10, 29 August 2013 (UTC)

And what inspired you to remove it without consulting anyone? (Other than that you believe chemtrails are a view of a "tiny minority," "fringe," etc.)  — Preceding unsigned comment added by 72.197.161.206 (talk) 22:54, 13 March 2014 (UTC)

Altitude
http://www.airspacemag.com/flight-today/Flight_Lines.html says At typical contrail-friendly altitudes, between about 28,000 and 40,000 feet, so Wikipedia saying Exhaust contrails rarely occur above 8,000 m (26,000 ft) is wrong. P.S., The exhaust particles in the aircraft's exhaust sounds not-smart. Jidanni (talk) 21:55, 15 November 2013 (UTC)


 * I'm not sure why you couldn't have done something about this yourself. At any rate, I have removed the redundant "exhaust".
 * Regarding your other concern, after reviewing the citation used for the information you've quoted ("Exhaust contrails rarely occur above 8,000m"), the cited source clearly states the following:

Contrails only form at very high altitudes (usually above 8 km) where the air is extremely cold (less than -40 degrees C). Other clouds can form at a range of altitudes, from very close to the ground, such as fog, to very high off the ground, such as cirrus clouds.
 * It seems that someone has tailored the information to suit their own needs, and I have accordingly edited the article to reflect the true nature of the information given in the currently cited source.  Illini407  talk 12:22, 20 April 2014 (UTC)

Sources listed
An IP posted the following discussion of possible sources to the article. The following was moved to the talk page for them. --- Barek (talk • contribs) - 16:09, 23 June 2014 (UTC)
 * Many abstracts and details of studies by NASA's Atmospheric Effects of Aviation Project (AEAP) are archived here url=https://web.archive.org/web/20010315000000*/http://hyperion.gsfc.nasa.gov/AEAP/98contrails.html ; the pages were taken offline between late November and December 2001. Some of the vast amount of information from these studies belongs and can be integrated here on this page. — Preceding unsigned comment added by 75.181.155.117 (talk • contribs) 16:04, 23 June 2014‎

Droplets?
Does the water in jet exhaust always condense to droplets, or does it sometimes desublimate directly to ice crystals? — Preceding unsigned comment added by Dan Wylie-Sears (talk • contribs) 14:52, 23 September 2005 (UTC)

Photo described as "Side-by-side contrail and distrail"
I'm pretty certain that that photo actually depicts a contrail's shadow on a lower cloud formation. — Preceding unsigned comment added by Kid entropy (talk • contribs) 17:50, 25 May 2016 (UTC)

Caused by soot nuclei and causing Global Dimming entailed is meaningless?
I have noted that in addition to vapour, engines produce soot, which additionally causes cloud formation to the extent that it is called a Global Dimming. My remark was basically a summarizing reference to the articles on cloud formation and global dimming, which support these claim. Nevertheless, my edit was removed as menaingless and unreferenced. I discuss unreferenced here. Why is it meaningless? Why is their material about engine-emitted water is meaningful but condensing air water by engine-emitted soot is meaningless even if the effect is as strong as Global Dimming and recurs as soon as cloud-friendly weather conditions are back? Watch the contrail videos yourself. A couple of contrails can easily take over the whole sky. The engine cannot emit the amount of water to span ten of kilometers wide -- this is condensation of the atmospheric water, aided by condensation nuclei. Cloud seeding works this way. Why is it meaningless? Do we have an article owner who will decide for us what is meaningful and what is not? --Javalenok (talk) 20:35, 10 October 2015 (UTC)


 * Hi Javalenok. As I said over on that WP:RSN section, you need to find a reliable source that makes the point that you want to make.  Summarising other WP articles, especially those that don't directly mention contrails, won't cut it.  If you think that's blinkered/silly, just consider what would happen on contentious or poorly-patrolled articles if people could just, effectively, make stuff up.  (Of course, it does happen on a lot of articles, but that doesn't mean that it shouldn't be challenged when someone notices it happening.)   Bromley86 (talk) 20:56, 10 October 2015 (UTC)


 * Javalenok, you need to provide a reliable source for your claim that soot produces additional clouds, i.e. clouds in addition to the contrail itself. To my knowledge, this is not true. The general other WP articles you cited do not say this. Aszilagyi (talk) 16:32, 13 October 2015 (UTC)
 * What, additional clouds? Indeed, referenced article does not say that. Saying that your soot produces clouds is not enough to say that it produces clouds. I see the point of additional now. --Javalenok (talk) 21:07, 10 May 2017 (UTC)

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