‘Are there any anti-CONTRAIL groups?’ was the title of a discussion that Ray von Geezer started on 30 September 2014 on Metabunk.org in the section ‘Open Discussion’. He wrote:
“Are there any groups who campaign against contrails rather than chemtrails? It’s something I’ve wondered about for some time but never found any evidence of, although recently I have noticed some chemtrail groups saying things like “regardless of whether you believe they’re deliberately spraying chemicals or not you should see these ugly trails are a problem”. [..] So, has anyone ever seen a group who simply just complained that otherwise clear skies were being visually “spoilt” by contrails without invoking “chemtrails”? ”
“Contrary to what you suggest, the main focus of my websites http://www.contrails.nl and http://www.meteologica.nl is not juston the visual impact of contrails, although it appals me ‘that otherwise clear skies are being visually spoilt (without hyphens) by contrails’ .
“I do not invoke “chemtrails” because polluting the higher regions of our troposphere and creating meteorological and climatological problems is already bad enough.”
My reaction provoked a (sometimes heated and personal) discussion on Metabunk.org in the section ‘Open Discussion’. It started on 30 September 2014 about contrails in general and more specifically about my calling them ‘aviation smog’.
Nick West, administrator of the website of Metabunk.org, pointed to my website Contrails.nl, calling it “the ‘Aviation Smog‘ site in The Netherlands” (that I had sorely neglected in the past few years..) After participating in the ‘open discussion’ on Metabunk, I came to the sad conclusion that it’s members accept that the air is polluted by aviation, but not that this could have any effect on weather and climate. My calling contrails ‘aviation smog’ was generally disclaimed.
As websites and blogs often disappear after a while, I use my own blog as an archive for my contributions and for a selection of (sometimes abbreviated) reactions from other participants that I found interesting or otherwise worth saving.
In the discussion on Metabunk.org about all the typical questions and (often derogatory) remarks about contrails (= aviation smog) and my pictures and texts came into play. The complete discussion with all the contributions can be read on the website of Metabunk.org.
Balance wrote in reaction #2 to Ray von Geezers article:
Bit like complaining of traffic noise after buying a house next a motorway, I guess. Not something I’ve given much thought about.
Hevach wrote #3:
The thing about reasonable people is that they have reasonable reactions to problems. The reasonable reaction to a streak of white in a clear sky, if that just really grinds your gears, is to turn the outrage knob up to about 1 or 2. It’s up there with stubbing your toe while you have shoes on, too much cheese on your pizza, or being stuck behind an inconsiderate person who leaves their cart in the middle of the aisle at Wal Mart. People do complain about those kinds of things, but if you dedicated yourself to one of them the way chemtrail believers pursue their craft… Well, people would think you were crazy.
Steve Funk wrote #4:
The first half of the Case Orange report was devoted to the adverse impacts of ordinary contrails in Europe. It was probably a collaboration, with the chemtrailers writing the rest of the report.
Administrator Nick West wrote #7:
There’s the “Aviation Smog” site in the Netherlands, but while it does not suggest deliberate spraying, it still suggests that contrails cause drought and other more dramatic changes in the weather. The main focus does seem to be on the visual impact of contrails though.
Nick West pasted an exerpt from my website Contrails.nl:
‘The word Contrail stems from ‘condensation’ and ‘trail’. Aviationsmog (that’s what it really is) is caused by airtraffic at great heights. Each day, jetengines of airplanes dump vast amounts of water (ice), CO2, soot particles (condensation nuclei), aerosols and chemical substances. Airtraffic thus not only alters the properties of the higher regions of our troposphere but also all the regions below, right down to groundlevel. This extra layer of man-made high-altitude smog probably infuences weather, climate and the quality and quantity of thesun’s radiation that reaches the surface of Earth (“global dimming.”). Aviation-smog is responsible for more clouds, rain, drought, bigger hailstones (megacryometeors), a stronger greenhouse effect (global warming), and, maybe, even gives extra power to hurricanes. Still, aviation-smog does not get the scientific and political attention it deserves.’
Hama Neggs wrote #8 and #9:
“There has been a recent trend toward avoiding any argument about the content of the trails by focusing on the visual aspect and sun-blocking, but no dedicated groups, afaik.”
Madison has been using the term “aircraft pollution” a lot when confronting officials on the matter.
Nick West wrote #11:
Yes, but she’s a true believer in the chemtrail theory, she actually thinks the long white lines in the sky are deliberate spraying. She’s not really “anti-contrail”.
Hama Neggs wrote #12:
No, but it’s just an example of how the language being used is not descriptive of what she/they really believe. It’s a (perhaps unintentional) hedging of their argument so that it can’t be countered. Who can rightly say that the trails in the sky are not “pollution” of some sort?
Nick West wrote #13:
I think there has been some “anti-contrail” rumblings from astronomers in the past, but did not get much traction:
Content from external source:
2 March 2006
Contrails often present little more than a transient nuisance to astronomers; but when certain weather conditions prevail, they can break to look like natural clouds.
Holger Pederson, an astronomer at the Nils Bohr Institute in Copenhagen, Denmark, who has studied contrails, explained: “You can recognise the jet contrails when they are young. So you can stop your observation and then restart as soon as the contrail has passed the field of view of the telescope.
“Worse is when the contrails last for hours. Then they degrade into something you can hardly distinguish from natural cirrus clouds.”
Dr Hermann Mannstein, of the German Aerospace Centre (DLR), agreed astronomy would become more difficult, but said there was an upper limit on the contrail problem.
Contrails form where the air is highly saturated with water vapour, but will not form if the air is too dry
“You don’t clog the whole sky. You have a certain proportion of the sky, in time and space, that can be affected,” he said.
This page exist only in the archive, and has lots of broken links.
Nick West wrote #16:
But the question here is if there are any genuinely anti-contrail people out there. Sometimes when I discuss the chemtrail theory with people who are very new to it, they end up agreeing that maybe they are just contrails, but then say “I don’t care what they are, they a messing up my sky” (or similar). But it seems they don’t really go on into anti-contrail activism. They either drop it, or go back to saying they are chemtrails:
Content from external source:
Chemtrail/contrails. I don’t care what they are. The fact is that i’ve seen many a clear blue sky turned in a hazey cloud-filled one pretty quickly. It might be done interntionally, it might not. It might be weather modification, it might just be standard air traffic.
But the truth is that this increase in air traffic is causing additional clouds to form, which in turn is affecting the weather. We are making clouds. This is weather modification whether intentional or not.
Analyst wrote #17:
Well I guess that’s the difference between the true believers & those with marketing concerns. I have seen one or two people that just seem more bothered by the aesthetic nature of contrails, but they keep bad company. How long their concerns remain purely aesthetic, I don’t know.
Hama Negg wrote #18:
But that just indicates that they think the trails are creating the weather, not reacting to it.
Nick West wrote #20:
Contrails do create cloud cover sometimes. It’s not unreasonable for people to dislike this.
Hama Negg wrote #21:
I suppose, but it gets all tangled up in the idea that the contrails created weather fronts, storms and rain.
Cmnit wrote #22:
IPCC devotes some of his efforts in the so called AIC (Aircraft Induced Cloudiness) because is a significant part of the anthropogenic causes of Climate Change, albeit a small one. Estimates say that AIC contribution is on the same ballpark of CO2 emissions from civil aviation. Good sources:
Germans are so serious about this that some proposals for Europe try to modify flight routes or heights in order to avoid ISRs (Ice Supersaturated Region) which are responsible for persistent contrails evolving in cirri.
It is also worth mentioning that at a conference of astronomers in 2002 on the topic of light pollution, contrails were discussed:
Light Pollution: The Global View. Proceedings of the International Conference on Light Pollution, Chile
Well. As noted, there can be occasions when contrails (due to an airplane passage in the upper atmosphere) can have a “trigger-effect” that induces further cirrus-type clouds to form in the region. However, I would argue (will need to find studies to back it up) that these cirrus clouds could very well form anyways, due to normal natural reasons.
Still….(again, another study is needed)….airplane contrails are just so “visible” that they have become a topic…”du jour”…if you will.
Certainly a LOT more polluting is occurring at ground level. (Witness many major cities in China, for instance)…..
Edit: Also, far too many times it seems that people who “complain” about contrails seem to think that they (the contrails) will somehow “fall” directly and vertically down upon them. There is a lack of understanding of how earth’s atmosphere actually works…..how vast it is in three-dimensions, and how upper winds affect flow patterns.
David Fraser wrote #24:
At the moment the issue of contrails is non really addressed by the major NGOs such as Greenpeace, however I expect that to change. We are looking now at the proposed expansion of Heathrow and quite possibly a few other over the next few decades and given recent studies on the effects of contrails I expect the specific protest groups like Airportwatch and Planestupid will latch onto that as a good arguing point. At the moment they mainly concentrtate on carbon emissions but I definately would be saying “Do you want to see more lines in the sky?” Now that would gain far more public support.
Weedwhacker wrote #25:
It is important at this juncture to note that an “expansion” of any specific airport (in terms of added runways, or increased ability to handle hourly traffic) is NOT related to contrails! Not directly, at least. Certainly the Air Traffic Control system and airspace that is becoming more ‘crowded’ is a slight factor…..but NOT specific airports.
David Fraser wrote #26:
Expansion is “needed” for the increase in air travel, which in itself is going to cause more contrails. People like Richard Branson are in favour of a third runway so they can open up new routes. Of course it is directly to contrails related especially given that there is an expected increase of 50% or more in passenger numbers by 2030.
Trailblazer wrote #27:
And just think of all that extra water being created by combustion! That’s got to cause sea levels to rise by a micron or two…
I remember seeing this a while ago [in the issue called
‘Environmental Justice’ of Essence (The University of Victoria Environmental Studies Student Association Periodical),
Volume 5 Issue 1 Spring 2012)]:
‘Final Boarding Call’
by Beth Bower
.. Airports have become the stage for some of the most emotional moments in our public lives. The toughest goodbyes we will ever have to say and the most magical of reunions are often played out here, amidst the duty free shop and metal detectors. But there is another drama brewing on this stage. It’s an epic one, whose global proportions transcend and knit together all of our personal stories. The actors include international corporations, carbon, technology, culture, and ultimately each of us. It is here on the public stage of the airport that we will have to face the truth about climate change and our love of flight. #at is, if we are going to have a real chance at curbing climate change, the days
of commercial !ight as we know it are over.
The reason behind this drastic declaration is a story line that we’ve all become increasingly familiar with over the past decade. Airplanes burn fossil fuels. And burning fossil fuels means greenhouse gas (GHG) emissions, which means trapping more of the sun’s heat, which means climate change. However, although related, the emissions from aviation are distinct from those of cars or home furnaces. Firstly, although the airline industry is adept at never mentioning it, there is the simple fact that airplanes travel long distances. In their latest bit of eco-PR Air Canada’s website proudly proclaims that:
Our latest aircraft use approximately 3 litres of fuel per 100 passenger/km . . . it compares favourably with the fuel efficiency of a compact car. (#e only difference: We go a little bit faster. Ok. A lot.)
What Air Canada does not mention is that those super speedy aircrafts cover distances like 11 170 km: the distance from New York to London and back again.
To gain some perspective, consider the fact that in the course of an entire year the average Dutch citizen will consume the same amount of fuel with their car that it takes to fly one passenger 10 000 km. That is, with a Dutch driver’s entire fuel allowance for the year, you could get from New York to London but you’d be kicked off the plane 1 170 km short of New York into the Atlantic. The issue here is one of scale; although fuel efficiency has increased, the sheer number of kilometres planes cover mean that they still release staggeringly high amounts of carbon.
And it’s not just carbon coming out of those jets. A myriad of GHGs result from burning kerosene. One of those GHGs is water. Oddly enough, one of the most vital conditions for life also acts as a greenhouse gas. When hot, moist exhaust rushes out of a jet engine straight into the icy upper troposphere, it crystallizes instantly. This is what forms those thin streams of exhaust that planes trace across the sky on a clear day. They’re known as contrails, and their effect on local temperature was recently revealed in an unexpected way.
In a perverse twist of fate, researchers at the University of Wisconsin were offered a golden research opportunity they never thought possible when planes were grounded for three days after September 11, 2001. While people around the world mourned, David Travis, Andrew Carleton and Ryan Lauristen got busy analyzing temperature data from 4 000 weather monitoring stations in the United States. Their results backed up what they’d long hypothesized. It turned out that with all the planes grounded, a significant increase in average diurnal temperature range could be seen. This meant that the difference between the temperature at night and during the day increased when planes weren’t in the sky. The contrails were acting like a blanket, insulating the continent from the natural decline in temperature that should occur when it faces away from the sun during the night.
Now, the fact that they got such significant results over just three days also means that contrail induced warming is a short-term phenomenon. No planes and the blanket effect disappears. But because planes are always in the sky, this short term effect is really a long term effect as far as any ecosystem is concerned.
The cumulative result of all these extra emissions is that the warming effect of a flight is more that just its calculated carbon output.
The International Panel on Climate Change (IPCC) has calculated an uplift factor to try to determine the true impact. They estimate it to be anywhere between two to four times greater than the warming effect of carbon alone. However, the science behind these calculations is still up for debate, and the IPCC warns that it is not as simple as just multiplying a given amount of carbon emissions by the uplift factor to figure
out total warming effect.
What is clear is that the climate impact of a plane ride is much more than just the sum of its carbon emissions.
The flight from Edmonton arrives, breaking my reverie. Why were these passengers up in the sky in the first place? Well, it turns out they were flying for business, for pleasure, and most often, to see family. I met a business man who flew every week for work, as well as a school teacher who rarely got on a plane — he was just there to pick someone up. But despite my head full of dark statistics,
I could hardly point a finger at the people I spoke with. After all, I’m guilty as charged. As a university student living away from home for the first time, there’s nothing as comforting as catching the sweet one hour flight back to Calgary every Thanksgiving and Christmas.
To simply stop flying appears to be a social impossibility. With the rush and globalization of our workplaces, and the scattering of our families across the map, how can we ever stay grounded? As one woman I spoke with put it, “We’d have no world!”
But what if this social impossibility is a social necessity? What if instead of viewing our need for grounding as a prison sentence, we paused for a moment and considered what would happen if we all stayed home. As an eloquent business woman at the airport put it, “maybe we all need to run around a lot less.” Perhaps if it wasn’t so easy to escape, there would be a revitalized interest in making our day to day environments more liveable. If we couldn’t go see the Louvre, we would want a thriving local arts scene and our own ways of communicating local history. If we couldn’t have destination weddings, we would want meaningful local places to celebrate. If students couldn’t fly away to university, imagine the pressure on government to provide each city with a top of the line teaching and research institution.
What all these “ifs” add up to is the possibility of cultural change. A social movement for staying put. Admittedly, I have danced around the issue of how exactly we will get there. I just don’t know. However, what I do feel more certain about is that clinging to aviation as a social necessity only reveals a profound lack of imagination. There is plenty of room to have expansive, diverse, and meaningful lives in our own backyards.
By: Beth Bower.
http://web.uvic.ca/~essa/wp-content/uploads/2012/03/ESSENCE-March-2012.pdf [page 6]
Robert van Waning wrote #29:
Contrary to what you suggest, the main focus of my websites http://www.contrails.nl and http://www.meteologica.nl is not juston the visual impact of contrails, although it appals me ‘that otherwise clear skies are being visually spoilt (without hyphens) by contrails’ .
I do not invoke “chemtrails” because polluting the higher regions of our troposphere and creating meteorological and climatoligical problems is already bad enough.
Efftup wrote #30:
Welcome Robert. Thankyou for providing some clarity.
You are aware of course, that whether a plane is making a contrail or not, those planes are still there, producing the same substances from their exhausts. When trails are visible, it is just a very easy way to show just how much Air traffic there is in our skies.
Have you compared statistics of how much pollution air travel is producing compared to cars/trucks at ground level for example, not to mention industrial processes?
Trail blazer wrote #31:
While what you say is true, on an aesthetic level I can see why people object to contrails. They undoubtedly do make it cloudier and will continue to do so. Estimates state that by 2050 many areas with heavy air traffic (especially the eastern U.S. and NW Europe) can expect greater than 10% contrail cover on an annually averaged basis.
Efftup wrote #32:
Oh yes, I can see the problem from an aesthetic level.
Robert van Waning wrote #33:
The pollution by airtraffic has more more effects on weather and climate than cars/trucks, industrial processes, heating of houses and buildingsd, production of electricity, etc. because of the level where during 24 hours of each day around the world aircraft dump massive amounts of watervapour and aerosols (acting as condensation nuclei). Weather is ‘made’ in the tropopause at a height of 10 – 13 km, exactly where the passenger- and freightplanes fly and burn their fossile fuel.
The effects of aviation smog on weather, climate and the Sun’s radiation are underestimated and euphemized, because nobody wants to know them. Research is too expensive and nobody is interested in the results.
On a flight from Amsterdam to Singapore a Boeing 777 takes 100.000 kilos of kerosine, I just read in a newspaper. Each day there are 30.000 flights in Europe alone..
Flying is far too cheap, because it is not taxed like any other means of transportation.
Nick West wrote #34:
But if there’s not enough research, how do you know how bad it is? The amount of water vapor added is very small compared to what is already there. So how is it affecting anything if if does not make a contrail?
Keefe wrote #35:
One or two contrails are ok, but when there are lots of them it is a kind of visual pollution – that might be what gets people started on chemtrail theories – it just doesn’t look right … for one thing [..]
Robert van Waning wrote 36#
A fair comment. Based on my knowledge of physics, meteorology, on what I have read about climate change, on my experience with weather, on my observations and on what I think is rational, reasonable and unavoidable, I think that the addition of enormous amounts of (quickly frozen) watervapour in combination with aerosols acting as condensation nuclei constitutes a major change in the higher regions of our troposphere that simply cannot be without consequences.
Also, research has been done in the past years, but not on the scale that – I think – is necessary. I myself have neglected this subject in the past years, but I especially remember the name of Patrick Minnis, an American climatologist. I have put many links to scientific reports on contrails etc., but many of them are outdated by now, I am afraid.
One effect of aviation-smog might be that it makes hailstones grow bigger. They are ‘born’ at an high altitude where there are now more far more condensation nuclei and more (frozen) watervapour than before aviation. Hailstorms cause ever more damage, because of the size and weight of the stones, that sometimes can gert bigger than golfballs. A friend of ours makes a good living removing the dents out of expensive new cars after a heavy hailstorm has hit a parking lot of a carfactory. He repairs the damage in such a way that the cars do not have to be painted anew. Have a look at these pictures:
Robert van Waning wrote #37:
In her article ‘Final boarding call’ the author, Beth Bowen [see above], writes:
“It is here on the public stage of the airport that we will have to face the truth about climate change and our love of flight. That is, if we are going to have a real chance at curbing climate change, the days of commercial flight as we know it are over.”
I think that this is true, because in the foreseeable future there is no alternative for the cheap fossile oil that aviation depends on. As a start, kerosine should be heavily taxed because of its nearing scarcity and because of the environmental impact of the way it is used.
Skephu wrote #38:
Is that only a conjecture or do you have studies to back it up? Ice crystals at cirrus altitudes grow bigger and sink, but as they reach an altitude where temperature is high enough and the air is drier, they evaporate and never reach the ground.
Robert van Waning wrote #40:
It is a ‘conjecture’ based on what I read and hear about heavy hailstorms that get more frequent, with bigger hailstones creating ever more damage. My friend who repairs the cars confirms that he is happily drowning in work.
It seems logical: Hailstones fall to the earth, but at hot weather they are lifted up again at high speeds by upward heated-up airstreams. At high altitudes with a temperature of minus 45 degrees Celsius they grow bigger by collecting more (frozen) water in an environment that has become saturated with it by the exhaust of airplanes.
Also, I think that hailstones are ‘born’ more often than before at higher altitudes because of the saturation of those regions with (frozen) watervapour and condensation nuclei by intensive airtraffic.
Trailblazer wrote #42:
There is more water vapour in the atmosphere than there used to be, @Robert van Waning, that is true. However the reason is not water from combustion: it is simply that the atmosphere is warmer than it used to be, and warm air can hold more water than cold air. That is also likely the reason for more violent storms (if indeed they are more violent, which is open to question). More energy in the atmosphere.
Robert van Waning wrote #43:
True, but I am talking specifically about the troposhere at an altitude of 10 – 13 kilometers. There the temperatures ar far below zero Celsius, but each day massive amounsts of water vapour and Aerosols (acting as condensation nuclei) are added each day by airtraffic. Tropical storms collect ever more ‘mass’ from these altitudes, thus growing in strenght, I think (‘conjecture’).
Henk001 wrote #44:
Exit conjecture and gut feeling. Enter science. A recent paper confirms that (persistent) contrails have a considerable impact on warming the climate:
Persisting contrails present the greatest impact on climate because instead of dissipating relatively quickly they linger, trapping heat beneath them. While contrails do block the sun to some extent, when they persist they also spread and become thinner, which means they don’t reflect as much solar energy away while still trapping heat.
“The net effect tends to be to warm the earth’s surface, rather than to cool it,” Carleton said.
The new research finds that in addition to shrinking the temperature range, contrails contribute to high-level cloudiness, which can contribute to warming the atmosphere.
Nick West wrote #45:
That makes no sense at all. Hailstones don’t form from water vapor, they form from supercooled liquid water. They form in thunderstorms which are saturated with water because they are rain clouds. The water comes from low altitudes, and rises by convection. The upper atmosphere water content has very little to do with it. The amount of water in just a single one square mile thunderstorm is more than the amount of water added by planes over the entire United States in a day.
It seems you are basing your claims on anecdotes and guessing.
Robert van Waning wrote #47:
Theories and hypotheses remain based on guessing as long as there is no scientific proof. So, should we stop guessing and worrying about developments that seem to lead to unwanted consequences?
My guess is that the upper troposphere get so saturated with frozen water vapour (condensated on soot and aerosols) that the origin of hailstorms will also be on those higher levels. Hailstones that are driven upward by convection, will meet more supercooled water on higher levels than before airtraffic reached the tropopause.
“If the relative humidity of the surrounding air at the altitude of the airplane is low, once the contrails have formed they cannot survive long as they evaporate through mixing with the surrounding air. In contrast, if the surrounding air is already above a relative humidity value sufficient for the formation of ice crystals, the ice particles in the contrails can survive for a much longer period of time. [..]
Along with the direct effect of the contrails themselves, it has been suggested that the extra condensation nuclei emitted in the exhausts might have a climatic influence once the contrails themselves have evaporated away. Their addition could cause the number of ice particles at the tropopause to increase so much that the later formation of natural cirrus clouds is made much more likely. These additional clouds can no longer be directly ascribed to the airplane emissions and hence are not included in studies of the contrail effects. The number of cirrus clouds observed in the last decades has increased however, which may be indicative of such an effect.”
(‘What role do condensation trails play in our climate?’
Robert van Waning wrote #48:
‘Blocking the sun’ is just mentioned sideways in this quote, but one of my guesses/worries is that this filtering of the sun’s radition will affect growth processes on earth. What part of the radiation is blocked and how crucial is that part for plants etc. to grow and live?
Most people who are aware of aviation smog, concentrate on its warming or cooling effect on the atmosphere. Personally, I am also worried about the ways in which affect the weather: Will it contribute to more frequent and heavier rainfall (and snow and hail) in some regions and thus to more drought in others? Will it contribute to the frequency and strength of tropical storms by giving them more mass?
(Pardon my English and my lack of proper scientific terminology. I am just a Dutchman who takes pictures of something that worries him, especially because it seems not to worry most people, including scientists, politicians, journalists and ‘weathermen and -women’.)
Trailblazer wrote #51:
Your guess cannot be right. You seem to be confusing relative humidity with absolute humidity. The air where planes form contrails is very cold and very thin – typically about -40 to -50°C and 200 to 300 millibars (one fifth to one third of sea level pressure).
Such air can hold minuscule amounts of water vapour compared to the warmer, denser air lower down. Hailstones form in cumulonimbus clouds, which contain orders of magnitude more water than even totally saturated air at flight level.
The tiny amount of extra water vapour in the air surrounding the top of a cumulonimbus cloud will not have any effect when compared to the massive amounts of water inside the cloud. Hail forms from supercooled water inside the cloud: water that is being carried up from the lower troposphere.
Also, as @deirdre points out, the limiting factor on hailstone size is the strength of the updraft. When the hailstone gets too big and heavy for the updraft to support it, it will fall to Earth. It’s not stopping growing because it’s running out of water to add, it’s stopping growing because it’s too heavy.
Robert van Waning wrote #52:
So we can all stop wondering and worrying and quietly go to sleep? Not me. I hear and read far too little about aviation smog than would be justified by the probability of undesirable consequences. In weatherprograms on radio and tv aviation smog is never called by a proper name and always euphemized as ‘sluierwolken’ (veil clouds’) like they were normal and natural and nothing can be done about this development. Smog on the surface is called smog, and quite rightly so.
The spokesman of KNMI, the Royal Dutch Meteorological Institute even had the nerve to say that on a particular day ‘there was not a single cloud in the deepblue sky’ whilst that sky in fact had been covered by aviation smog. “It’s a lobby, not a conspiracy” Tony Judt said in a different context.
‘Young’ and still small and light hailstones can be carried upward to the higher regions, where – I guess – they nowadays grow more than they did before. By the time they fall definitely because of their weight, they grow more than before as the atmosphere is getting more humid because of various reasons of which airtraffic is only one.
skephu wrote #54:
“Smog” is not a scientific term, and its meaning is not well-defined. Contrails do not differ from natural cirrus clouds very much. That’s why they are called “contrail cirrus”. The word “smog” implies lots of smoke, which contrails are not.
[RvW wrote: ‘Young’ and still small and light hailstones can be carried upward to the higher regions, where – I guess – they nowadays grow more than they did before.]
I don’t think that happens. Hailstones arise in low clouds, and they will never be carried up into high clouds.
Robert van Waning wrote #55:
We’ll see. My ‘errors’ are not more serious than your ill-based certainties. Also, while aviation smog is a wonderfully emotionally laden term, it’s not even close to accurate. Smog is a complex melange of pollutants near ground level, chief of which is ozone, a carcinogen. Contrails are more or less pure water ice at 30,000 ft. They are no more aviation smog than San Fransisco’s advection fog is marine smog.
A dictionary defines ‘smog’ as “Fog mixed with smoke and fumes from factories, houses, vehicles etc. Some big cities have a problem with smog.”
In its simplicity this is quite accurate. It says nothing that the location of this mixture should be at ground level for a correct use of the word. The term ‘marine smog’ could indeed be applied to smog originated by vessels.
Please have a closer look at my pictures on www.contrails.nl and try not to look at the stripes but at the vagues shapes between them.
Robert van Waning wrote:
The word smog does not imply a minimal amount of smoke but enough of it for water vapour to condensate on the particles. I doubt whether hailstones like shown in this picture originate in low clouds. Even if they do, on hot days they can be driven upward by strong convection winds to higher regions.
Here are a couple of links to heavy hailstorms with hailstones the size of golfballs and even tennisballs:
Huge hailstones in storms
This study suggests that hailstone diameter is expected to increase with global warming:
Change in hailstone size distributions with an increase in the melting level height
In France, the melting level height varies, during the hail season, from about 1 km in the spring to more than 4 km in the summer, and this parameter appears to have a connection with the mean characteristics of hailfalls. In fact, a large 25-year sample of hail size distribution measurements, made with hailpad networks along the southern Atlantic coast, reveals strong correlations between the melting level height and the mean hailstone number in different hailstone diameter ranges. On average, an increase in the melting level height is associated with a decrease in the number of small hailstones (5 to 7 mm diameter), has no apparent effect in the middle range (7 to 9 mm), and is concomitant with an increase in the number of larger hailstones, particularly in the 11 to 21 mm ranges. When the relationships giving the hailstone number in each diameter range as a function of the melting level height are applied to a given hailfall, an increase in the melting level height is then found to go together with changes in the total hailstone number and kinetic energy. From this observation, it is possible to estimate the potential effect of global warming on hailfalls with different hailstone size distributions. The trends in the monthly surface temperature and in the hail day melting level height observed at Bordeaux during the 1988–2012 period and the global warming projections made for the present century suggest that an increase in the melting level height of 500 m is forecast to occur in this region between 2000 and 2040. The consequences of such an increase for a standard hailfall in the region will be a slight decrease (− 12%) in the total number of hailstones, and a significant increase (40%) in total kinetic energy, but with no significant change in the hail frequency. This analysis is compared to the already observed increase in hail intensity in the area under study, and to observations, measurements, and numerical models in other parts of the world.
@Robert van Waning: You should try and find more scientific support for your claims. Like Skephu showed there can be a change in hail size without the contrails. Meteorologists and climatologists study a lot of the effects that contrails can have on weather and climate. If you can’t find any on the connection between hail and contrails (try google scholar) then your supposedly connection is probably not as obvious as you think, otherwise there would have been a study about that.
I personally think that Cirrus clouds (both natural and contrail induced) are not related to the formation of hail storms, because of the mechanism behind these storms, as pointed out above by several others. About this I found an illustrative site, in dutch mainly, but with a lot of nice animations (I don’t know how to copy a working animation here :(): http://www.keesfloor.nl/weerkunde/10neerslag/10neerslag.htm
You can always email the KNMI for questions about these things; perhaps you take them on an idea.
Robert van Waning wrote:
There is nothing wrong with expressing worries that are based on accumulated knowledge and on personal observations that seem to confirm them.
How could I possibly prove – albeit ‘somewhat’ – that aviation smog helps to make hailstones bigger and hailstorms more frequent? I think it does and you do not, without your being able to prove your opinion.
I’m going to let you slide on the misuse of the term “smog”- what you mean is “pollution”. That said, I hate to break it to you, but that pollution from planes is there whether you see the contrail or not.
Just look it up: All definitions of smog contain the combination of fog (water vapour condensation in an environment that is saturated for it) and smoke (soot, microscopic particles that act as condensation nuclei).
It seems that these drops cq crystals are hygroscopic. This would explain why those narrow contrails often grow into wide cirrusclouds. Many examples of this phenomenon can be seen on http://www.contrails.nl
Smog clearly is a sure symptom of pollution. What makes the pollution by planes special, is the place where most of it occurs, namely at a height of 10 – 13 km, where temperatures are around minus 45 degrees Celsius and where the original relative humidity was lower before airtraffic started raising it.
Robert van Waning wrote:
Just one page further on the website of the Dutch meteorologist Kees Floor, a graphic animation clearly shows how hailstones are constantly driven upward to regions where it is freezing hard and where they grow further until they get too heavvy: http://www.keesfloor.nl/weerkunde/10neerslag/hagel.swf
Kees Floor wrote about my contra-contrail activities on his website and in his beautiful book about clouds:
[Henk 001 wrote: You can always email the KNMI for questions about these things; perhaps you take them on an idea.]
Since 1995, when I started taking pictures of contrails and aviation smog and expressing my theories and worries about this development in our atmosphere, the KNMI has been as sceptic about my theories as most of you are, but in the past 20 years they have been losing ground for this scepticism.
Robert van Waning wrote:
[Hama Neggs had written: The term “smog” was coined to represent a FAR higher percentage of “smoke” than is ever present in contrails. You seem to be using the term because of its emotional impact rather than any true scientific similarity.]
Originally, yes. But meanings evolve. Houses are no longer heated with coalfires as in Victorian London. Those conditions hardly exist anymore anywhere in the world. The modern versions are ‘normal smog’ on the surface that is caused by roadtraffic and industry, and aviation smog on the level of the tropopause that is caused by airtraffic.
It seems that the emotional impact of the term ‘aviation smog’ is strong, which makes it effective to keep on using it.
Robert van Waning wrote:
Please have a look at the graphic animation that was published by the Dutch meteorologist Kees Floor:
Robert van Waning wrote:
[Hama Neggs had written: [The term ‘aviation smog’] is effective for someone who is trying to misrepresent reality.]
Come on. What other reality is there than airplanes dumping of ever bigger amounts of water vapour, soot and microscopic particles in the higher levels of our troposphere by airtraffic, causing unnatural cirrus clouds that have a similarity with smog?
Yes, I do know that cumulonimbus clouds can grow taller than the airliners’ cruising altitudes, but it is not the point. They grow from the bottom, not the top. The satellite images of the day show that those huge hailstones resulted from a naturally formed thunderstorm and are not likely to have been caused by the air traffic, which is negligible in that area. In fact, if a thunderstorm cloud of this size is formed on a regular traffic route, the planes normally would not fly through it but take a lengthy diversion.
Spectrar Ghost wrote:
[Robert van Waning had written: .., causing unnatural cirrus clouds that have a similarity with smog?]
They have zero similarity.]
Smog is a combination of the words smoke and fog, because it is smoke that clings to the ground like fog. It’s primary component is ozone, with soot, sulfides, and carbonates usually present as well.
Cirrus aviaticus (contrails) are identical in all respects except source to natural cirrus clouds. They are ice crystals. The nuclei make up a negligible portion of the cloud.
There is no way cirrus can affect hailstone development. At -40deg where cirrus form, the saturation point is 0.1 g/kg of water. At 20C (68F) which is a good dewpoint for thunderstorm development, saturation occurs at ~15 g/kg. this means that the updraft air initially contains 150 times as much moisture as any upper level air entrained into the storm.
Robert van Waning wrote:
[Spectrar Ghost had written: Smog is a combination of the words smoke and fog, because it is smoke that clings to the ground like fog. It’s primary component is ozone, with soot, sulfides, and carbonates usually present as well.]
None of those conditions and prerequisitions is mentioned in the regular defintions of ‘smog’. You just make them up for your purposes, whatever they may be.
Cirrus aviaticus (contrails) are identical in all respects except source to natural cirrus clouds. They are ice crystals. The nuclei make up a negligible portion of the cloud.
Contrails originate from the condensation of water vapour on particles, both coming from the engines of airplanes. This origin is not at all identical to the origin of natural cirrus clouds.
The upper parts of most hailstorms consist of cirrus, of which at least a part is aviation smog.
My theory is, that when any hailstone is sent upward several times for unknown periods through an environment that is saturated with ice, it grows inexorably by the ice-crystals or drops of deepfrozen water that attach themselves to its surface.
Spectrar Ghost wrote:
Content from external source:
Smog is a type of air pollutant. The word “smog” was coined in the early 20th century as a portmanteau of the words smoke and fog to refer to smoky fog. The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London from the 19th century to the mid 20th century. This kind of smog is caused by the burning of large amounts of coal within a city; this smog contains sootparticulates from smoke, sulphur dioxide and other components.
Sorry but your hailstone theory is complete bunk. If hailstones are ever present at contrail altitude it is because they are inside a thunderhead which has risen to that altitude. And a thundercloud contains vastly, hugely more water than any contrail cirrus, “aviation smog”, call it what you want. Hail forms INSIDE clouds which are already laden with water from lower altitudes. The minuscule amount of water in the upper atmosphere around them is totally irrelevant.
[Robert van Waning had written: It seems that the emotional impact of the term ‘aviation smog’ is strong, which makes it effective to keep on using it.]
Even if it is completely accurate and misleading?
I am going to be blunt. No there is nothing wrong with voicing concerns.
However, Your website is deliberately misleading and scaremongering.
You KNOW the way most people don;t understand the science properly so the use on your main page of adding in the words DUMP, AEROSOLS and CHEMICAL SUBSTANCES along with YOUR DEFINITON of smog (without a proper explanation) is deliberately meant to create an emotional response and create concern that was not there before.
All the chemical substances in the planes’ exhaust, WHICH INCLUDE CO2 and Water, are there in the atmosphere whether or not a persistent contrail exists, and you don’t see any kind of “smog” when there is no persistent contrail.
Practically all your posts on this thread have been couched in terms like “I guess” and I would think” and yet those words don’t appear anywhere on your website, and certainly not on the main page. It is set up to make it look like you have all the answers and this is totally disingenuous.
If your website simply showed all these lines in the sky as examples of just how much aviation traffic there was these days, and then voiced your concerns over the pollution, I would’t have a problem with it but I understand you want page hits. Sadly it is the way of the world now that even the more reputable news agencies are now resorting to pathetic clickbait and misleading headlines to get you to read their articles.
A random passer by, looking for information on “chemtrails” stumbling on your website is most likely to skim and not click too many links so what they will take away from your site is that planes are DUMPING AEROSOLS and CHEMICAL SUBSTANCES in the air and this is a danger. They won’t see that YOU and your website are actually disagreeing with the “chemtrail” meme and don’t appear to think any deliberate “spraying” is going on.
YOU will be touted as proof of the bunk that other people are spreading.
If you don’t want this, and want people to concentrate on actual pollution, I suggest a subtle rewording of your main page.
Robert van Waning wrote:
The question is whether an environment that is saturated for ice (like aviation smog) can help to make hailstones bigger? I think it can.
Robert van Waning wrote:
Aviation smog is caused by burning large amounts of fossile fuel (liquid coal) in an environment that is saturated for (frozen) water vapour.
The heads of thunderstorms are saturated for ice. Aviation smog just ads even more ice particles to them, with predictable results.
Weather is about margins: Will there be clouds or not? Will it rain, freeze, be foggy, etc., or not? Aviation smog often helps to tip balances between cloudless and cloudy, thin and thick cirrus, dry weather or rain, rain or hail, etc.
Aviation smog can make a cloudless with a clear deepblue sky turn into a day with either a thin deck of cirrus clouds whch can eventually – with the help of natural cirrus – get thicker and thicker. The microscopic droplets of the aviation smog and natural cirrus coagulate constantly and keep on growing until they get too heavy and fall down. I think these originally tiny droplets eventually could become icedrops and eventually hailstones. This is a theory. Don’t shout at me but tell me please why this cannot possibly happen.
It is my intention to create greater awareness and serious concern. People think too little about the many undesirable consequences of too much flying.
Not all the substances in the exhaust of airplanes are as innocuous as you suggest. Leaving chemical waste behind is called dumping. Water vapour is an underestimated greenhouse gas.
Weather is about margins and tipping delicate balances. The pollution is permanent; aviation smog makes it visible.
What I try to achieve is that people become aware of some of the consequences of all that careless daily worldwide burning of enormous amounts of fossile fuel in the higher regions of our atmosphere.
I did not take thousands of pictures of aviation smog (that’s what it is; let’s call a spade a spade) over the past 20 years for my personal album. I have a ‘message to the world’ but I am certainly not misleading people.
I am more concerned about the reactions that I got here than by what crackpots might do with my pictures, solid information and honest opinion.
The upper part of a thunderstorm lays in an area that nowadays is more saturated for ice than it was before airtraffic became massive and influential on meteorological processes. It is my guess that this development strengthens convective precipitation in thunderstorms and tropical storms (that actually collect saturated air from their environment, thus adding to their mass and power). The process of condensation of (frozen) water on particles in the upper ‘smoggy” regions maybe strengthens the upward movement.
Robert van Waning wrote:
[Trailspotter had written: Well, l am not going to comment on the thousands of pictures on your website, but I’ll make a comment on a picture that you posted in the beginning of this thread (#33):
It may look dramatic like a smog blocking the Sun, but in fact it is just a natural cirrus photographed against the Sun.]
But how ‘natural’ is that cirrus? Would it have been there and/or would it have been so thick whithout the permanent exhaust of fumes and water vapour by airtraffic? Aviation smog does not stay in one place, but travels at high speeds at high altitudes around the world, attributing to the occurrence of cirrus where it would not have been without aviation.
Thousands of airplanes weave a permanent ‘ice curtain’ around the world, glass curtain of icedrops and -crystals. That cannot remain without consequences. That is what I am trying to draw people’s attention to, just to make them aware and let them start thinking about it. In the past twenty years no expert has convinced me that I should stop with this.
Spectrar Ghost wrote on Jul 15, 2015 #99:
I think it’s important to note at this juncture that Robert has some legitimate concerns. Aircraft exhaust pollution is growing along with air travel. Increased cirrus cover in the form of contrails increases surface temperature on an already heating world. The aesthetic concerns, while subjective, are also perfectly legitimate.
However, for these legitimate concerns to be taken seriously, they need to be separated from the idea of “aviation smog”. Aircraft pollute whether they have a contrail or not. Contrails are not a cause of steadily increasing cloud cover (in the sense of steadily increasing, thickening, and lowering skies) but rather a forerunner, a forecast tool. We won’t rehash the hail.
Robert van Waning wrote on Juli 15, 2015 #100:
[SR1419 had written: That is your website? That was one of the first website I used for debunking “chemtrails” as it had links to pics of contrails from throughout history/movies etc… This was like 10yrs ago. Seems like you removed all the old stuff. ]
After 20 years most of the links pointing to scientific reports were dead. I have neglected my website http://www.contrails.nl for a long time. The page http://www.contrails.nl/contrails-research/ was not updated since August 2005. Maintaining it was a lot of work that seemed quite useless and utterly thankless. Over the past 20 years I received very little reactions. I have continued taking pictures, though, and in the past weeks I have rejuvenated the pages with pictures of the last 5 years with new software.
As to historic pictures and movies, I think you mean the website of the Danish astronomer Holger Pedersen with whom I had regular contact in the first years of my anti contrail ‘crusade’. Pedersen was triggered by the fact that aviation smog (I prefer not to euphemize this result of pollution) hindered astronomers in their work. He was convinced that looking at the stars etc. with conventional telescopes would become impossible because of the permanent cover of high clouds made by airtraffic. I wonder whether he is still active as an anti contrail campaigner.
I really had expected a different reception on this website. Here I may call contrails ‘pollution’ but not ‘smog’ ( which it is) and leaving behind the stuff that comes out of jet engines after their daily burning of massive quantities of liquid cole in the higher regions of our atmosphere may not be called ‘dumping’ (which it is). According a senior member of this website aviation smog is merely a ‘forecast tool’. I am speechless. This website is not about debunking chemtrails but about defusing contrails (aviation smog) by aviation enthusiasts.
Robert van Waning, Jul 15, 2015 #102
Spectrar Ghost said:
Contrails are not a cause of steadily increasing cloud cover (in the sense of steadily increasing, thickening, and lowering skies) .. .
How do you know? Just look at the pictures. Or rather: look at the sky:
Spectrar Ghost, Jul 15, 2015 #104
[Content from external source:
Cirrus clouds alone are generally associated with fair weather. However, if they are followed by a sequence of lower and thicker clouds, they are often the forerunner of rain or snow such as in an approaching warm front. When only Cirrus clouds are visible, there will usually be a period of fair weather of 12 to 24 hours. It usually takes that long for the rest of the lower-level weather to catch up.
“Cirrus Clouds can foretell the arrival of a Warm Front associated with Low Pressure systems: they are the first, telltale signs.
An approaching warm front has a distinct sequence of clouds.
1. Appearance of Cirrus cloud in a clear sky, or a sky with fair weather Cumulus clouds.
2. Appearance of ring or halo around the sun indicating a layer of cirrostratus cloud.
3. “Thickening” of Cirrus into denser cirrostratus or Cirrocumulus clouds.
4. Appearance of lower clouds– altostratus, then stratus.
5. Altostratus becoming nimbostratus and start of rain. Rain is steady and light.
6. Continuation of rain until the arrival of the actual Warm Front. This sequence will take 12- 24 hours from the first appearance of Cirrus clouds but ultimately it is dependant on how the front is moving relative to your own position. If the front is moving parallel to your position, it may never get to you. The beginning of the rain marks the approximate halfway point between the appearance or the Cirrus clouds and the arrival of the Warm Front. The barometer will steadily drop throughout this process. As the Warm Front approaches, the wind will veer suddenly and the wind may become gusty. After the Front passes, the wind speed and direction should remain constant.”
I have a book (Eric Sloane’s Almanac and Weather Forecaster (1955)) that specifically references this type of visual forecast as well.
Robert van Waning, wrote on Jul 15, 2015 #105 :
Could it be that has to do with the funnel-shape of depressions? Whenever a weatherforecast predicts ‘veil clouds (sluierbewolking’) coming in from the Northsea’, I make sure that I have my camera at hand because those words mean that aviation smog is going to spoil the blue sky. Most of the time a (in this region regular) depression is passing from the Atlantic over Scotland and the northern part of the Northsea towards Norway. What we then see, looking upward, is the upper fringe of the depression passing over Holland. (The areas in Belgium and Germany where most of the heaviest hailstorms occur, seem to follow the lines of the isobars on the weathermap.)
Spectrar Ghost wrote: #106
No. Low pressure systems aren’t funnel shaped. However warm fronts do have a gradual incline as seen above. Cold fronts have a steeper front edge. These fronts are typically laid out something like this as a cyclone/low pressure system is at its strongest.
Robert van Waning, Jul 15, 2015 #108 wrote:
Exactly: funnel-shaped. Much wider at the top than on ground level.
Robert van Waning, Jul 15, 2015 #107 wrote:
Look at how contrails grow into cirrus ( that is not natural):
Robert van Waning, Jul 15, 2015 #112
How do you know that cirrus is completely ‘natural’ and does not (at least partially) consist of icedroplets cq -crystals that originated by the condensation of (frozen) water vapour and aerosols, both coming from the exhaustst of jetplanes?
I mainly take pictures of contrails turning into cirrus that – after a while – can hardly be distinquished from natural cirrus. You can imagine what these contrails (the old and the new ones together) will look like, after a couple of hours or so:
(Picture by Dutch meteorologist Kees Floor.)
By observing them and by following their transformation from thin lines into wide cirrus clouds:
After the visible smog evaporates (at least becomes unvisible for us) the microscopic solid particle that had acted as condensation after leaving the jet’s enigine, can serve the same purpose later on, several times even.
No, we do not agree. Lows do not cover the same amount of square miles on the surface as higher up. They are not straight boxes moving around.
Contrails are not just helpful forecast tools. They are a result of serious pollution in the upper layers of our atmosphere and I think their effects on weather, climate and the sun’s radiation are undesirable, to put it mildly.
Or not. You don’t know without observing. And that is what I do before making pictures.
I’ve investigated many claims of contrail (“chemtrail”) grids spreading out to cover the sky with what you call “aviation smog” by looking at a “bigger picture” provided by the satellite images. In all cases, there was a cirrus layer coming into the area with substantial air traffic. As the layer approached, the initial contrails formed in the clear sky in the front of this layer, were replaced by new contrails formed within this layer. And the approaching cirrus was denser in the middle than near the edge, so from the ground it appeared that it gradually grew thicker. But the fact is, the incoming cirrus cloud would give the sky the same appearance even if there were no air traffic in the area at all.
PS And you seem to be aware of this, as the following passage of yours suggests:
Then wouldn’t you be better equipped to make your case that all that cirrus is created by spreading contrails rather than being an indicator ahead of a natural cirrus front, if instead of static pictures you use time lapses? The cirrus that forms from contrails is different to the cirrus layer that comes in later and is usually visually distinct from it; a time-lapse would show this much better than a singular frozen moment in time.
I did not write that – after a couple of hours – these contrails would remain visible from the same spot. I only asked what they would look like, wherever they were after a few hours.
Aviation smog that is visible over a certain area is most probably caused by airtraffic elsewhere in the direction where the high winds come from. [Why couldn’t] that first, second or umptieth layer of spread-out contrails therefore not be called ‘aviation smog’?
But again, I would suggest that in comparison to all causes of aerosols/pollutants, it is miniscule isn’t it?
I don’t think so.
PS Surely, the blue Dutch morning sky was spoiled later in the day:
[Trailspotter had written: What you call ‘aviation smog’ is merely a natural cirrus with a few contrails embedded into it.]
Yes, it was a good contrail day in Holland and over the North Sea
on April 5, 2007, as can be seen from the ground photos:
Still, the area covered by the contrails is much smaller than the area covered by natural cirrus coming from the South. Just as I pointed above, the long persistent contrails are formed in the front of the incoming natural cirrus.
[Trailspotter had written: You are not the only person who take pictures of clouds and contrails.]
I know, and I hope more people will do it and publish the pictures, preferably with sequences and films. It is good that people get more aware of the effects and consequences of too cheap )and so too much) flying.
I still do not understand that almost everybody seems to agree that contrails are a symptom of pollution, but that most of you are against the use of the term ‘aviation smog’. Let’s call a spade a spade and stop euphemizing, ignoring and even denying what is going on in the higher regions of our troposphere.
‘Tropos’ is derived from the Greek verb for living. Pollution of air is not only bad when it occurs on the surface.
And contrails don’t always need the soot from the engines to form. (not a big deal, just don’t want you to think i agree completely with that part of your sentence).
Did you ever read through www.contrailscience.com ?
I’m with Pete. If you arent going to make any attempt to show any real data- or convince us with anything other than guesses, bad science and trying to provoke emotional responses of fear -, I’m a bit confused what the point of this conversation is. Such tactics aren’t going to work on this particular website, you are going to get frustrated because you are basically talking to a bunch of nerds who are pretty serious about science.
If we switched to hydrogen fuel with pure water exhaust (which will never happen*), water vapour would not condensate on aerosols and I wonder whether the contrails would grow as wide as they now do most of the times. The ice-drops cq -crystals that make up ‘conventional contrails’ seem to be hygroscopic. Do you know more about that?*) The present scale of aviation will come to an end when fossile fuels really become scarce and so too expensive. Intensive flying consumes the fossile resources that future generation would have used more wisely.
Exhaust particles alone will not create a contrail.
Contrails form when excess water on the exhaust condenses on cloud condensation nuclei. This liquid water then freezes and it is thisfrozen waterthat creates the ice-nuclei for the contrail to form from.
If you just had exhaust particles sprayed into ice-supersaturated air, you would not get much of a contrail (if any).
And if you has just high humidity hot air (say, from a hydrogen engine) sprayed into cold air, you WOULD get a contrail, as there’s lots of natural cloud condensation nuclei.
After the ice has evaporated again from its nucleaus in a contrail, the same sootparticle can induce nucleation of ice again and again, as long as it remains up there. That is essentially different from spontaneous nucleation.
The contrails are almost everywhere, all the time, even when they no longer have the shape of thin stripes and so are no longer recognizable as ‘contrails’ but have become the vague haze that spoils an originally deepblue sky. The reason is that pollution by aviation is now virtually everywhere.
RvW wrote #175:
The ‘dense and persistent condensation trail’ that was left by the hydrogen fuel, is – by defintion – not a contrail nor smog, as they contain no particles that – after evaporation – can act again and again as condensation nuclei as long as the stay up there.
It is their almost permanent presence which makes that ‘aviation smog’ has become a permanent occurrence, although it no longer looks like the thin stripes of the original contrails. I call it ‘secondary contrails’ for lack of a better word.
According to NASA’s definition, contrails require ‘particles (aerosols) that exist in aircraft exhaust’.
But you are correct that NASAs oversimplification would seem to be saying ‘there has to be soot’.
Think of it this way… ice is a solid particle. so once the vapor from the plane condenses (we’ll say on the soot), now we have an ice crystal and a thin contrail line. As i’m sure you have observed, once that initial line has been laid, overtime the line will often appear to GROW (not just spread out but GROW thicker and spread). the reason for this is there is water vapor in the atmosphere. the water vapor in the atmosphere condenses on the ice crystals of the original contrail causing it to GROW.
I’m over simplifying of course, but trying to show that water vapor does not need soot specifically to condense. Think of your tea kettle. water vapor comes out of the spout and then condenses into ‘steam’ without any soot being present.
I am forbidden here to call the daily worldwide leaving behind of vast amounts of combustion products in a sensitive part of our troposhere that is essential for our weather, climate and radiation ‘dumping’.
I may not even use the term ‘smog’ for the clouds and skywide haze that are caused by the emissions of the ever more intensive airtraffic at 10 – 13 kilometers high.
I quickly started to wonder on what kind of website I had landed. Are you aviation enthusiasts and lobbyists, being sensitive about negative connotations of your hobby?
Contrails can form on particles that already exist in the air. Either in the air that is burnt, or the cold air it then mixes with.
Hydrogen burning engines make no particles, but leave contrails.
That depends on the definition that you use. My opinions are based on the NASA-definition, in which the presence of solid small particles is an essential element for the proper use of the term ‘contrail’ for this kind of vapour trail. Because of all the misconceptions, I will paste the full text here. I have stressed some parts of the text with * and bold letters.
This picture was made yesterday. It shows quite young, older and still older contrails. The oldest don’t look like contrails anymore, but like natural cirrus. It isn’t, though. Without the pollution by aviation, that part of the sky would have been cloudless and deepblue. Because contrails are the result of pollution, I prefer the term ‘aviation smog’.
Deirdre wrote #373:
Contrails are like “pigs in a blanket“. the “pig” is the pollution that ALWAYS comes out of engines. ALWAYS, whether you see it in the sky or not… it ALWAYS comes out of the engines.
The “blanket” is WATER> Ice chrystals that cling onto the “pig”.
The “blanket” ie the Contrail.. HAS been scientifically studied as far as its affects on climate. IF you used the term “contrail” you could use those scientific studies to PROVE your point. Because you do have a point, and its been scientifically studied. here is one ex:
Posting pictures without scientific context (dates times) is useless. You dont need to get more people interested in your cause, because the governments are already interested and studying and planning re: your cause.
Robert van Waning wrote #374:
[Landru said: Someone’s (your’s) attempt to add aviation smog to the Wikipedia article on smog was met with derision. https://en.m.wikipedia.org/wiki/Talk:Smog]
Anonimous derision, you mean, by people who do not have the courage to stand behind their own opinion (or lobbyism).
Anyhow, even you, as a would-be moderator of a would-be scientific forum, should know with how much derision new ideas, viewpoints and theories have been met that later have become fully accepted.
Basing myself on NASA’s definition of contrails, I think I can safely call contrails ‘aviation smog’, especially because it apparently hits a nerve.
I can’t really rememember ever having attempted to add aviation smog to Wikipedia. That must have been like almost 15 years ago, or so, in my activist years.
With aviation huge interests are involved. As David fighting Goliath I still hope that my pebble will hit a sensitive spot.
‘Nul n’est besoin d’espérer pour entreprendre, ni de réussir pour perseverer’, was the motto of William of Orange, ‘the father of our fatherland’.
Robert van Waning wrote #376
[Deirdre said: [..]The “blanket” ie the Contrail.. HAS been scientifically studied as far as its affects on climate.]
So I should rest my case, you mean? I won’t, because I do not think it gets enough attentin and research, and it is still not mentioned in the weatherforecasts as the real reason behind the cirrus that often clouds a sky that – without aviation – would have been cloudless, unpolluted and unspoilt.
I do not worry about global warming, because enough other people do. However, I do not hear enough about the probable effects of aviation smog on meteorological processes and on the quality and quantity of the sun’s radiation that reaches the surface of earth.
[Deirdre had written: THE “pig” ie. pollution from engines including planes. HAS also been studied. (and continues to be studied).]
Good! Never enough, though.
[Deirdre had written: Posting pictures without scientific context (dates times) is useless.]
So are your efforts to make me stop.
[Deirdre had wriiten: You dont need to get more people interested in your cause, because the governments are already interested and studying and planning re: your cause.]
Cute, naïve and undemocratic.
You are preaching to the choir Robert. We know all this stuff. Planes make cirrus clouds. Cirrus clouds warm the planet. Tell us something we don’t know. You seem to think we are denying or defending this. We’re not. Contrails are just one very small part of the many ways that mankind affects the atmosphere.
Focusing on contrails rather than the bigger picture shows a very strange lack of perspective. It’s like complaining about the pollution from the exhaust pipes of the cars that people drive to work at a coal-fired power station.
The thing is: I do not think aviation smog plays ‘a very small part’ in influencing the weather, the climate and the quality and quantity of the sun’ radiation that reaches the surface of earth. That is where we disagree, but we both lack the conclusive proofs of our supposition. Mine is based on the composition of aviation-induced cirrus (water vapour in combination with cloud condensation particles) and the place where it is daily and worldwide dumped in great quantities, namely straightaway in the tropopause.
I think we can stop here, unless some member of your community comes up with something that I cannot let pass.
You’re not really listening Robert- your too busy getting defensive- all your links-(most of which I have read before) simply show what we already know. Planes can make cirrus clouds. None of them definitively quantify the effects these cirrus clouds have weather and climate, none of them suggest these clouds have as much impact on weather and climate that you Believe. This not me being in denial, its me looking at the facts.
But you purvey your supposition as a “recognized fact”- That is illogical and suggests emotional bias.