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There seems to be a variety of issues surrounding the existence of contrails. Perhaps someone could clearly and succinctly describe what the concerns are... That they appear at some times and not others, Chemicals, unscheduled flights, exhaust products, etc.
It is apparent Hector that you and us here at Mysterious New Zealand approach the issue of Chemtrails from somewhat opposed directions. To you, Chemtrails do not, never have and never will exist. You probably feel rather patronising towards the poor deluded and ignorant folk who believe in such fairy stories. We have noticed that a hint of this patronising attitude reveals itself in some of your posts. Plus, you probably have a rather adversarial attitude towards the Chemtrail community (including us) and thus regard them/us as opponents to be quelled by the might of your superior scientific knowledge. Of course we may be misjudging you here and you may, in reality, be open-minded, non-biased and without vested interest as is the true scientist, a sadly vanishing breed. If we have misjudged you, then we will apologise, but at least you know how we feel and we all know where we stand...
We do not mean to be derogatory towards you Hector, and hope you will take the above in the right spirit, To us it is better for all to be honest and have all their cards on the table. After all, it wasn’t that long ago that science scoffed at the notion that meteorites were a reality. Rocks falling from the sky, eminent scientists declared, “ was an absurdity”. Hard to believe today that such a stance could have been taken by scientific giants such as Newton and Lavoisier – and despite all the evidence. Meteorites could not exist therefore they did not exist. QED.
We actually wrote an article on this subject some 10 years ago and reread it from time to time as it helps to maintain our perspective about science. As we’ve recently placed it on Mysterious New Zealand, it can be found here:
We have been researching these issues since the name 'Chemtrail' was coined in the late nineties. To us there are two very serious issues to be concerned with. One is to do with ‘Chemtrails’ and the other is regarding ‘Cirrus Aviaticus’ and the effect of both on the well being of our planet and the world’s population. But first a little history…
It is easy to forget that the original furore was due to a sudden onset of thousands of trails in the late nineties that almost appeared overnight over many parts of the USA and Canada (and in other parts of the world).
Witnesses were suddenly observing aircraft travelling in directions where no valid destinations existed, jet traffic in locations outside the normal flight corridors, planes leaving prolific and persistent contrails, forming parallel lines, grid patterns, crosses and circles. Later these were also observed to be occurring at night.
It was suspected that these were military craft and they were also seen to be spraying - not just leaving contrails. It was apparent to those on the ground that what they were experiencing (and photographing) was a huge military operation. But the authorities remained tight-lipped on the matter despite the airforce bases being inundated with highly concerned citizenry jamming their phone systems. It also seemed that the mainstream media was imposing a news black-out on the subject, refusing to take seriously the many reports they received, even from their own reporters.
The occurrences were so unusual and so dramatic that when they first began, they caused much public disquiet - drivers would become distracted as they craned their necks to see the strange lines in the sky, groups of people would stand around looking up at the lines and grids and the resulting dingy haze as the trails spread out.
Far from previous normal contrail behaviour, instead of dissipating in the usual seconds to minutes that people were accustomed to, these new trails were lasting for hours at a time, spreading and growing over time to form huge banks of cirrus cloud. Often associated with strange pink and green colour effects, many people describe as ‘sinister-looking’. The cloud thinned out to form a general haze over the entire visible sky in what is often referred to as the 'white sky effect'.
Samples of discernible fallout were collected and analysed and found to contain unusually dangerous levels of various chemicals such as Aluminium and Barium.
Many folks felt that they the people were the target of the operation, after all, the US government/military has a well-documented history of spraying various substances on their people, or of exposing them to potentially harmful chemicals and subsequently denying it.
The concerns seemed justified when hospital emergency services were suddenly inundated with sick people. Not surprisingly, the illnesses were associated with the aerial spraying, particularly when doctors had difficulty diagnosing the cause of the various symptoms, mainly respiratory in nature. Many regarding it as a form of mass hysteria or similar.
After some time, it was reported by ground observers that the nature of the delivery system seemed to have undergone a change. Now it was observed that the trails were originating from the jet engines themselves, in the same way as usual aircraft contrails. Commercial aircraft also seemed to be now laying similar trails to the military tanker craft on the usual commercial flight paths. Some researchers noted that there were patents in existence for the delivery of oxides of Aluminium and Barium in such a manner.
The frequency of patterned spray operations, however, remained undiminished.
In March 2001 a radio reporter Tiffany Brendt and partner Lou Aubochont of West Pond in rural Maine counted 30 jets laying down thick contrails, extending from horizon to horizon, within a 45 minute period. An air traffic control manager indicated there were only nine commercial jets showing on his radar and that Brendt should only have been able to see one of those jets in her location at that time. In the many decades they had lived in West Pond, they had never seen so much aerial activity. Aubochont, a former US Navy Intelligence Courier was used to large scale military exercises, but he had never seen anything this big before - “It looked like an invasion.”
On the same day, at Tiffany’s radio station, WMWV, the assistant news director and his staff had gone outside and counted 370 aircraft contrails overhead, where normally there would be none.
Such startling accounts of this sudden onset of prolific contrail activity were typical and were echoed all over the United States, Canada and in many other countries around the world at the time.
Here, for example, is a very revealing report of some research using Flight Explorer conducted at that time (2001) above Houston Texas:
For several years the existence of an unusual type of aerial activity has been reported, generally termed Chemtrails. Chemtrails are purported to differ from typical contrails in their high degree of persistence and subsequent spreading, as if a substance had been released. The purpose, effects and existence of these so-called Chemtrails are widely debated, however essentially there is a claim made by many that they are witnessing something out of the ordinary, beyond an ordinary contrail. Chemtrails are also said to sometimes differ in their configuration from contrails, as they are supposedly not about getting from point A to point B, but, rather, dispersing some type of substance.
Goals
While it is scientifically accepted that normal contrails may persist for hours and spread, the research represented in this report attempts to use the tools available to make a scientific analysis into the veracity of the Chemtrail claims by attempting to isolate any data that might show evidence of such activity.
Summary of Results
The goal of this research was to determine if there was a type of trail that was inconsistent with normal contrails, especially with regard to increased persistence. What was found is that highly persistent trails that last for many hours were seen above Houston, TX on a majority (60%) of observable days during the data collection period. However during this time period none of the 46 Flight Explorer confirmed contrails observed persisted for over 30 minutes and most contrails were under 30 seconds of persistence. Additionally it was discovered that the jets that were responsible for leaving highly persistent trails that last for hours did not ever appear on Flight Explorer and were documented for 8 separate instances, including one instance with two jets in formation. These unidentifiable jets were found to produce a contrail that was consistent with confirmed contrails during the periods when they weren't leaving highly persistent trails. Highly persistent trails are often seen in the form of isolated relatively short strips, as well as large areas of cirrus aviaticus clouds, but on rare occasions have been seen in totally unique grid and wheel formations.
It is hoped that others will endeavor to repeat these observations and publish their results. By repeating the basic observations for persistence length and whether the flight appears on Flight Explorer, it will be seen whether or not a trend emerges confirming the existence of a unique category of trail. Atmospheric differences due to higher moisture and colder temperatures in different locations will produce greater maximum persistence observed for identifiable traffic. For those in locations with greatest contrailing potential, the task of collecting data on highly persistent trails from unidentifiable flights will be hardest.
In this research I have gone to great lengths to measure and characterize my observations as accurately as possible in order to provide the clearest representation possible given the resources available.
Mark Steadham
All this was strangely compelling, that is, what the 'Yanks' were doing to themselves, like watching a somewhat distasteful event happening to somebody else, from a distance. Over this time we did not look too deeply into the detail of the phenomena, but did keep an eye on the overall issue. Thank God we live in New Zealand, we felt, so far away from all this madness. A visit to Marlborough on photographic assignment for a prominent wine producer in April 2003 however, brought home to us a very different reality...
I am pretty sure, John and Melody, that at one time you were aware of the existence of jet engine exhaust condensation and thought it unimportant, benign, though spectacular in some instances. At some stage you received some information that suggested something different. At that point you did a "180" and we find ourselves in somewhat opposed directions, as you say.
I don't think I have advanced the opinion that "Chemtrails do not, never have and never will exist". It is unfortunate if terseness is taken to be a patronising or superior tone. It is clear that some here have been reading the Chemtrail sites for years, so a contrary opinion will probably look that way. You have misjudged, and I accept your appology.
My concern here is that, to some who post, every jet engine exhaust condensation cloud they see is evidence of a sinister chemical spraying operation and proceed to get worked up and rant and rave about it. I am wanting to impart some knowledge and tools to enable people to excersise some discernment and appreciate what this phenomenon is, and is not... as I did with the "radar beams". The appearance of contrail "grey beams" is under dicussion under another topic.
If "they" are persuing a chemical spraying operation from high flying planes, then you are not going to prove anything or convince anyone to take any notice (let alone commence an official investigation) by all this barking at the moon.
Have you considered that your web site prejudges the issue before anything is even observed or analysed by having topic titles containing "Chemtrail" and generally conveying a negative connotation to the phenomenon. This doesn't seem to me to be an open minded, scientific or rational approach to the issue.
Your allegory about the meteorite controversy is an interesting effort to put this issue in some sort of context. The problem with it is that the meteorite arguement was not the same as the chemtrail one is. The accepted
scientific wisdom was that it was impossible for rocks to fall from the sky. That was eventally changed. The phenomenon of jet engine exhaust condensation is well known and well understood in the scientific, aviation and military community. Now, no one is saying that it is impossible to apply a chemical from a high flying plane - of course it is possible. The question is, Are they doing this? and, Are they doing it in New Zealand? My opinion: possibly, and probably not, respectively.
The history of the apparent rise in the reported occurrence of jet engine exhaust condensation (or whatever) has to be temperted with other technological and social developments such as:
1 the rise in accessability of this type of information via the Internet and the consequent increase in awareness of the issue
2 changing and improving jet engine design and characteristics, and improving atmospheric measurement and sensing technology
3 the increasing distrust in transnational corporations, governments and government agencies, and the inexplicable appeal of supporting any one of the whole genre of conspiracy theories.
As you have said in the sticky top post in the reporting area, there is research and there is research. The standard of research I have seen on some of the American based web sites is poor. I will later post an analysis of the example at
http://watchthesky.org/chems/trailimage.htm
linked from http://watchthesky.org/chems/evidence/evidence.htm
to demonstrate the point. I wonder how many more there are like that, and how many of them have contributed to the hysteria.
You have identified two issues which you consider important enough to be concerned with: ‘Chemtrails’ and ‘Cirrus Aviaticus’ and their effects on the planet and its population. Well, possibly.
Let's accept that jet engine exhaust condensation is the expected behaviour in suitable atmpsphereic conditions, and that these conditions together with the characteristics of appearance (persistence, etc) can be diagnosed and forecast within a reasonable margin of error.
Let's also accept that every plane flying can be accounted for and is going about its legitimate business whatever that may be: transport, spying, spraying, training, excersising, goofing off, whatever.
Now, as I see it, only three questions arise:
1 On any day, at any location and height, either jet engine exhaust condensation is possible, or it is not.
2 Either "they" are spraying chemicals from high flying planes, possibly disguised in or as jet engine exhaust condensation, or "they" are not.
3 On a certain day, at a certain location and height, either ‘Cirrus Aviaticus’ is, or is not observed.
So there are eight possibilities. It would is illuminating to assign an observation into one of the eight possible cases. Of course, the answer to question 2 is undetermined; the point is to clarify your thinking. For instance, there is the possibility that "they" are spraying chemicals and you can't see it. It's a bit of a mystery to me why there is no ranting and raving on days when jet engine exhaust condensation is not observed (and not possible); only on days when contrails are observed (and expected).
Let's just suppose for a minute that "they" are not spraying chemicals anywhere.
Jet engine exhaust condensation may not be the most aesthetic of cloud forms, and there may be consequences for the radiation budget in some parts of the world leading to climate change issues. Given that it is a consequence of the particular physical properties of water substance, and the combustion of hydrocarbons for air transport is not going to stop anytime soon, there is
nothing much you can do about it.
So that brings us down to the chemicals issue at a particular place and time.
You can only legitimately raise that when you have eliminated the other seven possibilities. I think you will find that there are only four possibilites, the answer to question 2 being "NOT"; in New Zealand at least.
I am pretty sure, John and Melody, that at one time you were aware of the existence of jet engine exhaust condensation and thought it unimportant, benign, though spectacular in some instances. At some stage you received some information that suggested something different. At that point you did a "180" and we find ourselves in somewhat opposed directions, as you say.
In our nearly 100 years of collective time on this earth, prior to April 2003, the two of us had seen perhaps a handful of jet contrails, ever. Both very keen observers (particularly important in our respective careers during those years) and enthusiastic skywatchers, in the very early days, a jet contrail was still a very rare and wonderful, memorable even, event. Nowadays these contrails are common to a point of almost normality. And while they are not as common here in Auckland, we have nevertheless seen a fair few of them in the past few years – more than we would have expected to see if were basing predictions on a lifetime of experience in the Auckland area. (For many years, we lived in several homes with spectacular views of the Auckland skyline, working from home with constant awareness of that sky and never having seen one contrail, persistent or otherwise.)
It was not received information but direct observational experience that really impacted on us back in 2003 in Marlborough. What we saw and photographed on that day, not only anomalous aircraft contrails, but the 'black line' and other oddities, suggested to us that there is something going on, that is not normal and not right. We are currently working on an article about this, which we will publish in due course.
Despite having seen many dozens of spectacular contrails since then all over New Zealand and despite the fact that many (not all) are consistent with what seems to have become 'normal' aircraft emissions from 'normal' aircraft on 'normal' flight paths, our view still remains that something unusual is happening in our skies, at times, that is anything but normal and that doesn't fit the explanation of normal international, civilian or military flight activity. What that is, we don't know with any degree of certainty.
Hector wrote:
I don't think I have advanced the opinion that "Chemtrails do not, never have and never will exist"
You have said “No one is spraying chemicals.” Perhaps such an absolute statement could be construed by some as 'do not, never have and never will'.
Hector wrote:
My concern here is that, to some who post, every jet engine exhaust condensation cloud they see is evidence of a sinister chemical spraying operation and proceed to get worked up and rant and rave about it. I am wanting to impart some knowledge and tools to enable people to excersise some discernment and appreciate what this phenomenon is, and is not... as I did with the "radar beams". The appearance of contrail "grey beams" is under dicussion under another topic.
Some, but not all, posters take that view. And some, but not all, posters rant and rave. We tend to discourage ranters and ravers on this forum and have developed a standard for respectful and reasoned discussion which, for the most part, prevails. You may have noticed in your extensive research into 'chemtrail sites' that many such forums simply degrade into insults, name calling and pointless and staunch defense of a preferred view. We are doing our best to encourage genuine inquiry and informed observation. It should be remembered that it is, however, a forum.
What we have found is that there are a lot of frustrated people out there. People who are seeing things they know to be anomalous and potentially problematic and are frustrated that they cannot seem to get any acknowledgment of their observations. Because their observations seem to characterise a relatively new (to them) phenomenon and because those observations disturb them, many of them naturally look to the internet for possible explanations of what they are seeing. In our experience, in most cases, it is the observations that come first, followed by the quest for more information – not the other way around.
And, perhaps surprisingly, it is not always the speculation about 'chemical spraying' at the forefront of their minds. We have many contacts from people who are concerned about the impact of contrails as pollution (not all of them choose to take part in this forum). This is an aspect, along with grave fears about the resulting global dimming and its potential impact on the warming of the earth, not without some concerned mainstream backing. Recently, we reported on an article on the BBC web site where astronomers were predicting that the effects of contrail cirrus were becoming so serious, that “ground-based astronomy could be impossible in 40 years because of pollution from aircraft exhaust trails and climate change”.
Source: Cerro Tololo Inter-American Observatory
Source: Cerro Tololo Inter-American Observatory
Hector wrote:
If "they" are persuing a chemical spraying operation from high flying planes, then you are not going to prove anything or convince anyone to take any notice (let alone commence an official investigation) by all this barking at the moon.
Have you considered that your web site prejudges the issue before anything is even observed or analysed by having topic titles containing "Chemtrail" and generally conveying a negative connotation to the phenomenon. This doesn't seem to me to be an open minded, scientific or rational approach to the issue.
The reason we began these forums was primarily to gather the experiences and observations from other people around New Zealand and to see what was happening and what people were seeing. After our Marlborough trip of 2003 we spent nearly a year researching and considering what we had seen before even contemplating documenting any of it on the Internet. In fact, Mysterious New Zealand was already an idea we had had for collecting together information on other genuinely mysterious things from a New Zealand perspective and part of that 2003 trip was to visit with someone in possession of a highly anomalous object we were to photograph. We had no thoughts of making the 'chemtrail issue' a part of the site.
It has to be said that during the time the forums have been in operation our continuing research has modified our views a little. And we are certainly more reluctant to use the term chemtrails as freely as some of our other forum members. Personally, we now reserve the term for a very specific type of anomalous activity. We do however, defend the use of the term on the web site. Anyone embarking on a quest for information will eventually happen across the term and will begin to base their searches on it. We want people to find this web site.
We should think that, given the “Telescopes worthless by 2050” article referred to above, the 'negative connotation we give the phenomenon' is most appropriate. The growing cloudiness of the skies around the world is very much an issue that touches people on the very deepest of levels. The enjoyment of a clear cloudless sunny blue sky day is an unparalleled delight. Sometimes referred to as the 'white sky effect', the idea of our world becoming increasingly cloudy and dimmer due to aircraft emissions, is in our opinion, potentially very upsetting - not simply just a matter of the aesthetics of contrails themselves.
We would challenge your implication that we are not open minded, scientific or rational. Having said that, this is a forum, not a scientific journal. Our aims for it are to share, acknowledge, discover and learn and to be a vehicle, as best we can, for sound and rational dissemination. We hope that our articles in particular, will serve this function most significantly. As you can appreciate, these take time to put together and we look forward to being able to present some useful and down to earth information on the subject. One such feature (currently in development) is a history of the persistent contrail from the first sightings in 1919 to the present day. We do subscribe, however, to the view of noted astronomer Sir Fred Hoyle, who said “I don't see the logic of rejecting data just because they seem incredible'. Which brings us to the meteorite example...
Hector wrote:
Your allegory about the meteorite controversy is an interesting effort to put this issue in some sort of context. The problem with it is that the meteorite arguement was not the same as the chemtrail one is. The accepted
scientific wisdom was that it was impossible for rocks to fall from the sky. That was eventally changed...
It is interesting that meteorology shares the same derivation as meteor - from the Greek 'things or phenomena in the air'. Don't you think?
Our point about the meteor story is the readiness of scientists without the benefit of personal observation to dismiss, ridicule and pronounce that something doesn't and cannot exist. And that it holds the visual observations of ordinary folk to be virtually useless, imagining that the average person isn't capable of making rational observations. True, many ordinary people may lack the verbal deftness to express what they have seen in a compelling way or perhaps lack the courage or the will to pursue the observations to a logical conclusion. Sometimes they may not understand all there is to understand about what they have seen. However, sometimes scientists make some very arrogant and belittling judgments about the anecdotal evidence of average citizens.
You say that “the phenomenon of jet engine exhaust condensation is well known and well understand in the scientific, aviation and military community”. Well no, actually. Ulrich Schumann is considered to be a world authority, yet some of his theories and explanations are still hotly debated, and in some circles, disputed by fellow scientists. There is also much concern and investigation into the problem of contrail induced cirrus cloud, how it affects the atmosphere and the temperature of the earth, the polluting effects of the coming exponential increase in aircraft activity and how all of this might be ameliorated. It is widely acknowledged that all of this is not yet fully understood. There have been proposals to add aircraft emissions to the Kyoto protocol. There have been proposals for some kind of tax on the 'damage' that aircraft do in the course of their flights around the world. Naturally, because no one can agree on how to determine who is responsible and therefore, culpable for fees payable, this remains 'up in the air' so to speak. Interestingly, British Airways runs a scheme called Climate Care, where passengers can calculate the relative impact their flight will have on climate change and pay a fee which goes towards various environmental schemes. An excerpt from their site:
"When I fly, am I contributing to climate change?
Yes. Aircraft operations generate carbon dioxide (CO2) emissions, a direct greenhouse gas, and other effects in the atmosphere for which there is less scientific understanding, linked to ozone generation, methane reduction and cirrus cloud formation.”
Hector wrote:
The history of the apparent rise in the reported occurrence of jet engine exhaust condensation (or whatever) has to be temperted with other technological and social developments such as:
1 the rise in accessability of this type of information via the Internet and the consequent increase in awareness of the issue
2 changing and improving jet engine design and characteristics, and improving atmospheric measurement and sensing technology
3 the increasing distrust in transnational corporations, governments and government agencies, and the inexplicable appeal of supporting any one of the whole genre of conspiracy theories.
As we said above, it has been our experience, that people's observations and their concerns about proliferation often occur first, then their investigations, most often through the Internet. Do you also imagine that more people are now becoming sick because there is better access to information about medical conditions and illnesses? We do not believe that more awareness of the incidence of contrails and persistent contrails accounts for the proliferation of the trails themselves. Also as per some of our post above, in our opinion, it would appear that the incidence of contrails HAS increased during recent years.
Changing and improving jet engine design as a reason for increased contrail formation is, we believe, another controversial area still under debate. Once again, the work of Ulrich Schumann in this area is a case in point. We are researching this very complex area and gathering information for an article. Better measuring and sensing technology is, once again in our opinion, not an explanation for a proliferation of contrails.
Increasing distrust in transnational corporations etc is probably a very real and justified concern, particularly as our society inches its way toward the ultimate total surveillance of its citizens in all manner of respects. Unfortunately, yes, the 'chemtrail issue' does attract some who are looking to make it into a religion or to add it to their long list of world ills that prove everyone is out to get us (see some of the more extremist of posts on this forum). We do our best to discourage that kind of approach here.
Hector wrote:
As you have said in the sticky top post in the reporting area, there is research and there is research. The standard of research I have seen on some of the American based web sites is poor. I will later post an analysis of the example at
http://watchthesky.org/chems/trailimage.htm
linked from http://watchthesky.org/chems/evidence/evidence.htm
to demonstrate the point. I wonder how many more there are like that, and how many of them have contributed to the hysteria.
It's a bit of a mystery to me why there is no ranting and raving on days when jet engine exhaust condensation is not observed (and not possible); only on days when contrails are observed (and expected).
We will have more to say on this, however, our example of the Far North seemed to pose some challenges for analysis. Only by guessing at probable data were you able to satisfy yourself that the predictive model for contrails produced a positive result for that day. Using data for Whenuapai, a considerable distance from the area in question (which, incidentally does not fall beneath normal flight vectors of aircraft coming into or going out of New Zealand – we will soon be uploading our completed map of flight vectors) and by guessing values not determined by the radiosonde were you able to declare success on that result. We feel that this particular analysis remains under a shadow...
Hector wrote:
Let's just suppose for a minute that "they" are not spraying chemicals anywhere. Jet engine exhaust condensation may not be the most aesthetic of cloud forms, and there may be consequences for the radiation budget in some parts of the world leading to climate change issues. Given that it is a consequence of the particular physical properties of water substance, and the combustion of hydrocarbons for air transport is not going to stop anytime soon, there is nothing much you can do about it.
Also stated above, there are good reasons for concern about what is considered to be a 'consequence of the particular physical properties of water substance' and what is more, there is some serious discussion taking place on the matter. One proposal that has been put forward as a possible solution to the problem is to have aircraft fly at lower altitudes, thereby reducing the incidence of contrails and consequently, of flight induced contrail cirrus. Predictably, airlines have not been keen on this approach as it would impact on fuel efficiency and damage profits. It would seem that, once again, the fate of the environment and thus, our world and its future continues to be a matter of money.
Hector wrote:
So that brings us down to the chemicals issue at a particular place and time.
You can only legitimately raise that when you have eliminated the other seven possibilities. I think you will find that there are only four possibilites, the answer to question 2 being "NOT"; in New Zealand at least.
Your opinion - not a scientific one because you don't have all the facts. None of us can know whether this is occurring or not. The only way to know is to have a plane up there flying in the wake of the contrail with sampling equipment. And, Hector, that ain't gonna happen – not in this country.
Perhaps one day you'll be at a certain place at a certain time and see something that will shake you out of your scientific certainty... :-s
They point out, correctly, that Whenuapai is distant from the area where they were observing and photographing these clouds. I said that the tepmerature at 300 hPa over the Far North was 1 degree warmer than over Whenuapai. To obtain that figure, I went to the NCEP Re-Analysis site and got a plot of the
300 hPa analysis for midday that day. That's how I know it was 1 degree warmer - I did not guess. I could have done the same for RH, but there was no need. You can tell that from all the cirrus (not counting the contrail cirrus) in the photos that the RH at those altitudes would be fairly high. That's not a guess either - it's a reasonable deduction to make from an observation; an observation of data, the photos.
It's not my conclusion. The conclusion follows from thermodynamics and the data on the day.
John and Melody also seem to be questioning that jet transport planes were legitimately flying those skies that day.
In the section "Contrail Formation and Persistence" the author says that Various numbers are quoted as the threshold temperature for contrail formation but does not mention the Applemann methodology, MINTRA, or any other techniques for finding out that the threshold temperature is, or even that the threshold temperature varies with height (pressure) and depends somewhat on relative humidity.
The object of the reserch was to see if there were some contrails that were different in some respect from what could be chracterised as "normal", so it is not surprising that there is no interest in determining if "normal" contrails are at all possible at an altitude that something is observed. For the same reason there seemed to be little interest in recording instances of aircraft identified in Flight Explorer that were not contrailing.
Anyway, the conclusion was that there were 46 contrails lasting 30 minutes or less (mostly 30 seconds) all identified in Flight Explorer, and 8 contrails lasting some hours and all of these not identified in Flight Explorer. He said that military flights are filtered from the data stream by the FAA for security reasons. The conclusion from that (which Steadman does not state) is that these 8 were probably made by military aircraft. There could be reasonable explanations for military aircraft making persistent contrails. To investigate that properly you need to know the altitude they are flying when they are observed.
The 8 persistent contrails occurred on the same days as transient contrails, so apart from persistence and the aircraft not being identified, there is nothing to distinguish them. You will probably say, "That is exactly what distingishes them!" Well, possibly. I don't think it necessarily means that there is now irrefutable proof that "they" are spraying chemicals from jet air planes.
It would be interesting so see results of similar research done in summer. Upper temperature and moisture conditions are quite different winter/summer.
What are your thoughts on persistant contrails which have cut points. I am referring to the switch on switch off effect of the lines I observe. Persistant contrails which start in the middle of the air, carry on for a few kilometres then stop as if switched off. The trail does not carry on at all, not even a sign of it. Even if the aircraft has moved into a different band of air pressure/temperature you should see a thinning or patchy trail carry on but nothing. What this looks like is that the aircraft has fired up its engines in the middle of the air then turned them off after a short distance (ridiculous you agree). This is the reason I began watching in the first place, way too anomalous to explain away.
You have been following these analyses, Deano, and reading the background litereature so you will know that the cut-off temperature for the formation or not of contrails depends on pressure and relative humidity. At lower pressure (higher altitude) the cut-off, or critical temperature is lower. For a given pressure, the higher the relative humidity, the higher the critical temperature.
You will notice that the critical temperature is very sensitive to RH above 50%. For instance for a contrail factor of 0.039 g/Kg/K (high bypass engines) at 300 hPa, the critical temperature changes from -50.04 at 0% to -49.23 at 50%; a change of less than 1 degree Celsius. But it is -41.81 at 100%, a change of 7.42 degrees.
This disparity is similar at all pressures (altitudes), more so at higher pressure (lower altitude). For a graphical representation of this, look at the critical temperature box in any of the analysis charts.
The 50% RH line is way closer to the 0% RH line (left) than the 100% RH line (right). The box is narrow at the top and wider at the the bottom.
Aircraft cruise at a constant pressure (flight level), and the air temperature does not change very much along a constant pressure surface; certainly not on the distance scale of a few kilometres. But relative humidity does, especially I think if the flight path is across (more or less perpendicular to) the wind direction at that level. Therefore the intermittent appearance of contrails is the response to changes in the critical temperature along the flight path because of changes in RH. Only fairly small changes are required (if the RH is high) to change the cut-off temperature for contrailing by a degree or two, to above (no contrail) or below (contrail) the ambient air temperature.
I hope this helps to explain the appearance of those off and on contrails you have seen.
