Climate impact of clouds made from airplane contrails may triple by 2050
From the EUROPEAN GEOSCIENCES UNION
In the right conditions, airplane contrails can linger in the sky as contrail cirrus – ice clouds that can trap heat inside the Earth’s atmosphere. Their climate impact has been largely neglected in global schemes to offset aviation emissions, even though contrail cirrus have contributed more to warming the atmosphere than all CO2 emitted by aircraft since the start of aviation. A new study published in the European Geosciences Union (EGU) journal Atmospheric Chemistry and Physics has found that, due to air traffic activity, the climate impact of contrail cirrus will be even more significant in the future, tripling by 2050.
Contrail cirrus change global cloudiness, which creates an imbalance in the Earth’s radiation budget – called ‘radiative forcing’ – that results in warming of the planet. The larger this radiative forcing, the more significant the climate impact. In 2005, air traffic made up about 5% of all anthropogenic radiative forcing, with contrail cirrus being the largest contributor to aviation’s climate impact.
“It is important to recognise the significant impact of non-CO2 emissions, such as contrail cirrus, on climate and to take those effects into consideration when setting up emission trading systems or schemes like the Corsia agreement,”
…says Lisa Bock, a researcher at DLR, the German Aerospace Center, and lead-author of the new study. Corsia, the UN’s scheme to offset air traffic carbon emissions from 2020, ignores the non-CO2 climate impacts of aviation.
But the new Atmospheric Chemistry and Physics study shows these non-CO2 climate impacts cannot be neglected. Bock and her colleague Ulrike Burkhardt estimate that contrail cirrus radiative forcing will be 3 times larger in 2050 than in 2006. This increase is predicted to be faster than the rise in CO2 radiative forcing since expected fuel efficiency measures will reduce CO2 emissions.
CREDIT Bock and Burkhardt, Atmos. Chem. Phys., 2019
The increase in contrail cirrus radiative forcing is due to air traffic growth, expected to be 4 times larger in 2050 compared to 2006 levels, and a slight shift of flight routes to higher altitudes, which favours the formation of contrails in the tropics. The impact on climate due to contrail cirrus will be stronger over Northern America and Europe, the busiest air traffic areas on the globe, but will also significantly increase in Asia.
“Contrail cirrus’ main impact is that of warming the higher atmosphere at air traffic levels and changing natural cloudiness. How large their impact is on surface temperature and possibly on precipitation due to the cloud modifications is unclear,” says Burkhardt. Bock adds: “There are still some uncertainties regarding the overall climate impact of contrail cirrus and in particular their impact on surface temperatures because contrail cirrus themselves and their effects on the surface are ongoing topics of research. But it’s clear they warm the atmosphere.”
Cleaner aircraft emissions would solve part of the problem highlighted in the study. Reducing the number of soot particles emitted by aircraft engines decreases the number of ice crystals in contrails, which in turn reduces the climate impact of contrail cirrus. However, “larger reductions than the projected 50% decrease in soot number emissions are needed,” says Burkhardt. She adds that even 90% reductions would likely not be enough to limit the climate impact of contrail cirrus to 2006 levels.
Another often discussed mitigation method is rerouting flights to avoid regions particularly sensitive to the effects of contrail formation. But Bock and Burkhardt caution about applying measures to reduce the climate impact of short-lived contrail cirrus that could result in increases in long-lived CO2 emissions, in particular given the uncertainties in estimating the climate impact of contrail cirrus. They say that measures to reduce soot emissions would be preferable to minimise the overall radiative forcing of future air traffic since they do not involve an increase of CO2 emissions.
“This would enable international aviation to effectively support measures to achieve the Paris climate goals,” Burkhardt concludes.
###
The publication is in Atmospheric Chemistry and Physics – link to the paper
Some thoughts:
- This is a model output, so take it with a grain of salt.
- They seem to only consider the Long Wave IR to space reflectivity for contrails as being the big forcing component, yet there’s a big reflectivity factor for incoming solar radiation too. And, that’s got to be considered. If contrails were only reflective one way (from the surface looking up) we’d not be able to take photographs like this one from space:
NOTE: Any discussion of “chemtrails” in this comment thread will be immediately deleted. -Anthony
There was no quantification of the current warming from contrails. Any increase could (will) be de minimis.
not even a 1/10th of the nose level. Unquantifiable outside of some BS cargo cult model simulation, where they hide the huge error (uncertainty) bars, as they always do.
Agree, just like CO2 emissions.
It does not matter whether the effect is immeasurable, the aim is to build an agenda for banning air travel for ordinary citizens. The way they blatantly only look at one side of the equation before drawing conclusions makes it obvious this is not about science.
Why do you think this is the last thing the academics wanted to look at?
(Hint: academics fly more than many other groups)
ConAir
While looking for the paper I mentioned below, I found this from 1970:
https://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1970)027%3C0937:AOOCEO%3E2.0.CO%3B2
Airborne Observations of Contrail Effects on the Thermal Radiation Budget
“Direct infrared and solar radiometric observations were made to analyse the effects on the environment of any alterations in the radiation budget in regions of heavy jet traffic. The observations, made from the NASA Convair 990 jet laboratory, were coupled with Mie scattering and absorption theory calculations to analyze any inadvertent alterations in the natural atmospheric thermal radiation budget. It was found that a 500 m thick contrail sheet increases the infrared emission below the sheet by 21% but decreases the solar power below the sheet by 15%. The infrared increase cannot make up for the solar depiction, resulting in a net available incoming power depletion at the base of the sheet of 12%. Such a change at altitude results in a 7% reduction in the net total available thermal power at the earth’s surface, which, in turn, results in a 5.3C decrease in the surface temperature, if we assume contrail persistence. The actual temperature decrease is ∼0.15C with 5% contrail persistence.”
Net cooling! Did the European Geosciences Union bother to search the existing literature? Or were they more interested in adding to the propaganda.
Bill, this article confirmed my immediate response to the headline: contrails are visible, hence they reflect visible light, hence they remove energy from “above the greenhouse.” HOWEVER: where there is smoke there is fire / where there are clouds there is water vapour. We all know that non-condensing water vapour is the dominant greenhouse gas. Perhaps the invisible aircraft contrails are a larger problem than the visible ones?
Has every one forgotten 9/11 and the grounding of all non military US aircraft flights for several days? It warmed the temperature. No clouds, no shade. Rain from clouds cools surface temps.
It’s really amazing isn’t it? I couldn’t believe the last sentence of the article so I had to look. The paper doesn’t even include the words albedo, solar, or reflection. There’s no way they can be this dumb so it must be pure fraud. Propaganda is something documentary makers and governments do, in science it’s fraudulent.
Thanks for the link Bill, that paper looks much more informative.
I looked at the paper this article refers to and it is not at all clear what they are considering. It seems based on an earlier paper where they report on the model they used in creating this paper. They seem to be involved in propaganda , not science, so I did not waste my time chasing that any further.
They are clearly out to produce results to justify restricting air travel on the assumption that it is “bad”. Ironically, since particulate stratospheric pollution and cloud seeding are actually cooling the planet, reducing plane travel will likely have the opposite effect of what they claim: global warming. OOPS !
Jet fuel also contains sulfur compounds that form SO2 upon combustion, which subsequently reacts to SO3 and forms reflective aerosols.
That sulfur level is declining with regulations that remove sulfur from other distillates, especially diesel.
+10
One potential solution would be to restrict air traffic to below the altitude thresholdat which Contrails form about 26,000′ – 35,000′. Limit Air Traffic to below 25,000′ and trails do not form for most of the year
There is NEGATIVE warming from contrails.
9/12/2001 and 9/13/2001 had a ground level heat spike of about 2°F because of a LACK of contrails. Those were the days that air traffic was grounded across North America.
I thought clouds had a net cooling effect ? Yes they warm at night, but during the day they reduce the overall incoming radiation which has a larger cooling effect than the night time warming,
Altitude. Clouds high enough trap and reflect, but definitely trap.
Lower altitude mostly reflect
Why?
It’s not about trapping – instead the cloud is blocking IR from the ground and replacing it with IR from the cloud. That IR from the cloud is at the temperature of the cloud, so the higher it is, the colder it is, the less IR that is emitted.
So, relatively high temperature IR being emitted from the ground is replaced by relatively low temperature IR being emitted from the cloud and there is a reduction in IR.
Yes but they are reflecting/absorbing incoming visible and IR light. The net effect is cooling. I don’t think they stick around too long into the night.
My understanding is that at lower altitudes the greenhouse effect is generally saturated. It is only as get higher that photons are most likely to make it into space. In addition, you are also above most of the clouds which are also radiating from their tops. This expands the area that is available to absorb photons to near 100%.
Higher clouds tend to be thinner allowing SW IR to pass through but also reflect LW IR.
Lower clouds tend to be denser and reflect incoming SW IR negating the LW IR from being reemitted (Cloud base height and density is the key)
Don’t ask why. It is Settled Science. What are you? A denier?
But at higher altitudes there is little to no heat to “trap”
Its not heat, its energy.
Heat is one form of energy but energy can be other things as well (kinetic, potential, etc, etc)
Is night time “warming” the correct phrase? The amount of night time Cooling is slightly lessened, temperatures are not increasing after sunset …… except perhaps in some urban environments where heat is being given off from buildings ….
The unfortunately statistically inconclusive study of warming/cooling during the post-911 grounding of US air traffic, showed a few degrees of warming IIRC. Though it was not possible to exclude the possibility that a natural variation could have caused this.
The nearest thing we had to an actual climate experiment showed that less flights=global warming.
Also both El Chichon and Mt Pinatubo stratospheric eruptions ( which concerns exactly the heights where most commercial flights pass ) resulted in a cooling of the lower stratosphere in the years which followed. This implies greater transparency.
That greater transparency allows more solar into the lower atmosphere and accompanied the period of “catastrophic” warming arbitrarily attributed to AGW.
It seems likely that the removal of avionic pollution caused warming. Again, contrary to what this one-eyed study is trying to concluded.
Of course, if they had found that more flights mitigated AGW, they would not have got published, would have been ostracised by the climate community and would have lost all funding.
Earth: an ancestor simulation to see if humans would argue about an essential just above starvation level photosynthesising useful trace gas 😀
I thought that one of the big problems with Global Climate Models was that they couldn’t tell whether clouds were, on balance, positive or negative forcing?
“…that they couldn’t tell whether clouds were, on balance, positive or negative forcing?”
Unless they are man-made clouds, which creates an additional suitable leverage-point for the activists for their blame-pinning.
Yeah, GCMs don’t actually model clouds, but add in a postulated effect for clouds.
See! I said we were doomed!
due to air traffic activity, the climate impact of contrail cirrus will be even more significant in the future, tripling by 2050. ??????
I thought we were supposed to be extinct by just after 2030??? End of fossil fuels because we’re all fire-roasted marshmallows (heat charred on the outside, gooey soft in the middle) and all that.
You know… Climate catastrophe, climate weirding, climate collapse and all that Watermelon bull schist.
As far back as the 1970’s there has been talk about contrail weather and climate effects. A paper somewhere around 1973 or so talked about possible negative effects of contrails dimming sunlight on agriculture. That paper also discussed how contrails, in certain conditions, can grow into sizable banks of cirrus, an effect I personally have witnessed many times from the ground and the air. What the net effect might be on global energy balance is debatable. A freshman level atmospheric sciences class I took about the same time in the 70’s claimed cirrus are net heaters while cumulus are net coolers and stratus can be either depending on thickness of the layer. All I know for sure is a cirrus between me and the sun is welcome when mowing the lawn in summer and irritating when shoveling snow in the winter — it feels cooler.
I used to play golf a lot and when cirrus clouds were present it was a pretty sure bet that there wouldn’t be any thunderstorm development and thus no lightning. We always liked it when the cirrus clouds appeared as it allowed us to just go and play without worry.
I recall an article on this subject from a few years ago, but can’t find it. Immediately after the 9/11 attacks, all air traffic in the United States was halted for several days. “Scientists” used the opportunity to check the effect this had on global warming. I forget what they found, but it was an actual case of a large-scale change in human contributions to environmental change, and thus, to global warming.
The increase attributable to the absence of contrails was one degree C.
Here it is
https://www.sciencedaily.com/releases/2002/08/020808075457.htm
It only says the temperature range increases, not if contrails warming or cooling.
BUT… clouds have a cooling effect
The NASA scientists involved did not mention that the 9/11 attacks occurred when there was a large dome of high pressure over the East coast that would have led to cooling in September. They instead blamed cooling on the lack of contrails – there probably would have been no contrails anyway. Contrails only occur in high humidity which is why on many days there are a none and others they are very apparent. The number of flights is around the same it is just that there may be insufficient humidity at the aircraft cruising levels for contrails to form.
Contrails only occur in high humidity which is why on many days there are a none and others they are very apparent.
True. I live under an area of major flyover routes in the US central Appalachians, and there are many more days of zero to hardly any contrails than numerous/persistent contrails.
In Sydney, there are far fewer persistent contrails than we see in the US, even accounting for the smaller number of flights. The typical contrail behavior above the Sydney area is for contrails to be about 1km long, and dissipating, if they are visible at all. You might see one or two that last for more than 1/2 hour once a day, if that.
Seems our typical humidity at altitude, combined with a generally lower number of particulates, restricts them from forming the “streets of cloud” we see in the US.
Contrails are much, much more visible EARLY in the mornings, just before the Sun rises above the horizon.
The reason being that, …. with the sun “rising” in the East its sunshine will be “reflected” off the underneath of the contrail’s water vapor droplets, ….. thus making them visible from the surface if the viewer is underneath or to the west of the rising Sun.
And as the Sun climbs higher above the horizon …. the contrails start disappearing as if there was “magic” involved.
A similar thing goes for the nearly always present layer of CI at 30K in the tropics. You can only see it at sunrise and sunset. I remember when on Guam the two observations around sunset and the two around sunset always had 300 -OVC (30,000′ thin overcast)
i noted the massive increase in sky clarity in pics from then
i also note our rural skies cloud over after as litle as 6 planes do a series of runs over my area and a nice clear sunny day becomes dull and not so nice.
the greenvirgin branson plans hundred more planes in air for his profit..carbon offsets my a$$
dont get this mindless jump on a plane go somewhere mindset people have, at all.
for Ausies its cheaper to go to asia for a fortnight than one week in our own nation for a holiday, yet fuel etc use is so much more.
Remind me – After the September 11 attacks all air traffic in US airspace was stopped for… 3 whole days(?)
If I recall correctly there was a measurable change in recorded temperatures during this period because there were of course no contrails getting between the ground and the sun.
And, correct me if I am remembering wrong, but the observation was that WITHOUT contrails in the sky… IT GOT HOTTER.
These people are either desperate or lacking in basic reasoning abilities. If the models do not match the observations, then it is probably your models.
A quick Google showed plenty of articles on the effects of stopping air travel after 9/11, here is the first: https://globalnews.ca/news/2934513/empty-skies-after-911-set-the-stage-for-an-unlikely-climate-change-experiment/
The big effect of removing contrails was an increase in temperature range of about two degrees Celsius.
So contrails cool during the day and warm during the night, net change seems to be warming, but that is smaller and so less certain.
Contrails are net cooling. More contrails means more cooling.
Quoted from
https://journals.ametsoc.org/doi/pdf/10.1175/1520-0477%281997%29078%3C1885%3ACCATPF%3E2.0.CO%3B2
Conclusion
“consensus of the experimental and model findings given here suggests that the climatic effects of contrails, persisting on the order of minutes to hours, may more likely lead to a cooling of the surface of the earth
rather than to greenhouse warming”
Next we’ll have Ocasio-Cortez screaming that the high temperatures from jet engines and car engines heat the planet. 🙁
Someone who would say that is correct. There is a lot of waste heat released into the atmosphere through electricity generation, internal combustion engines, heating and air conditioning buildings. Cooking releases heat into the atmosphere.
I would theorize that the waste heat released into the atmosphere is the sum of all human contributions to “global warming.”
Every type of energy will transform to heat.
Do you know that the energy realeased by human over the last 40 years would be egnough to heat ALL water in the Mediterranean sea?
Not so much in the big picture, but a human caused global warming that is real and not fake like CO2
Much of the engine heat (from my limited expertise) comes from the inefficiency of extracting work from combustion. Liquid fuel is burned producing vapor byproducts where latent heat of the vapor is not recovered as work by the engine. So while the engine does lose heat, it also emits water vapor as a combustion product which acts to increase the dew point and thus the nighttime minimum temperature. Regarding contrail vapor, jets generate maybe twice the water vapor per hour on take off (while moving slower) than they do at altitude (at cruse speed). As such, one would expect an increase in nighttime minimum temperature, especially in the areas around airports.
Someone with actual data or experience – please add to or correct my understanding.
By 2030, all air travel will be displaced by high speed rail. Of course, this only lasts for one year until the world ends.
What is it with the year 2050? Everything must be done to stop climate change, in 30 years! It’s like fusion, always 30 years away.
The real question is why the change.
It is absolutely true that contrails did not behave in this way in the past. That is to say, persisted and spread out into massive clouds. Has the fuel changed. I did read somewhere that more sulfur is added to fuel for more pressure for high altitude flight. This would have an effect?
Going by the sat images of the UK of contrails being persistent and spreading out, it absolutely affects the energy balance, how I don’t know.
Why do contrails now all too often plaster the whole sky and often even here in Finland make the whole sky silver.. is a question I wonder about.
Is adding more sulfur to fuel a way to experiment with SRM?
No idea, no conspiracies 😀
More airplanes, much more. And contrail amnesia.
There are many contributing factors for a change in condensation trails in Finland.
At higher altitudes, wind speeds are higher. So airliners want to be as high up as possible, if they can catch a tail wind.
– With the use of larger, more powerful engines, airliners can fly higher.
– Thanks to composite hulls, airliners can better withstand fatigue.
– The reduction of costs, has led to an increase of passenger numbers.
– With newer, long range models, polar routes between Europe and Asia have become an option.
– Thanks to long range models, the Hub and Spoke model is no longer needed. Airliners can use small, less congested, low cost airports.
– China has become a more important destination.
Every time I read about some nutty professor trying to use SO2 for Geo-engineering, I think; Just stop removing Sulfur from Jet-A.
Not true. The paper I mentioned above talked about this happening in the 1970’s and I have heard anecdotal stories from WWII pilots that the contrails left by the Allied bomber formations over Europe occasionally spread out to form solid cirrus layers that would play havoc with the later follow-up photo recon missions, forcing them down to lower (more vulnerable) altitudes to complete their missions. Persistent contrails and contrail seeded cirrus layers have been around a long time.
It was very noticeable in 2010 when the eruption of the volcano (with the unpronounceable name) resulted in all air traffic being grounded for a number of days. The immediate effect was the very clear blue skies and an apparent increase in sunshine intensity, very similar to the intensity the I experienced in New Zealand.
When they allowed the air traffic to resume it was also noticeable that the intensity fell, and how quickly the sky filled up with what seemed like very thin clouds.
There didn’t seem to be any warming effect, if anything the opposite.
Some photos I took showed the effect of the contrails, but I should have also taken some photos while the air traffic ban was in force.
“Jet contrails will likely affect climate by 2050”
Er – won’t we be using matter transfer to beam us to our destinations by 2050?
Or Gravity Trains ( https://en.wikipedia.org/wiki/Gravity_train )?
We’ve been waiting since Hooke invented the idea in the 16th century for these. A bit longer than our ‘flying cars’….
The IPCC has had one since it’s inception. Btw, you misspelled ‘gravy’.
They have been saying this for maybe 40 years and have never provided evidence
“Aircraft contrails can spread into cirrus-like clouds high in the atmosphere. Similar to natural clouds, they are thought to have an overall warming effect on the planet. But they can also moderate daily temperature extremes by trapping heat that escapes from the ground and reflecting sunlight. This raises the lowest overnight temperatures and, to a lesser degree, reduces the highs during daylight hours, scientists have suggested.”
https://www.nature.com/news/2008/081231/full/news.2008.1335.html
“When all commercial air traffic in the United States was grounded after the terrorist attacks of 11 September 2001, scientists got an unexpected opportunity to test ideas about the climate effects of the condensation trails left behind by jets.”
https://www.nature.com/news/2008/081231/full/news.2008.1335.html
(united nations)” ignores the non-CO2 climate impacts of aviation”
Yeah, that’s why you pay in EU a very creatively calculated few bucks of NOx mitigation tax included in the ticket price.
Although I have never seen NOx mitigation machinery units being financed with those taxes. Collected money just vanishes as usual.
Chemtrails are produced by high performance aircraft. Nothing to worry since by 2020, 2030, 2050, anywhere around there, birds, blimps and electric aircraft are the only supposed to fly.
Not far away from where I live, a small company (2 on payroll) attempts to put 1’800 kg of batteries in a Cessna 172, stretch it’s fuselage and add a second electric motor in the tail section.
To the latest news, first transatlantic flight is expected to occur in 2020. We all wish them good luck.
By 2050 The West will be even more bankrupt. Poor people don’t fly.
Right Robertvd, reason why I suggested my kid to become a lawyer. The more poor, the more rich will need legal means to contend them.
https://www.dutchnews.nl/news/2019/06/support-for-climate-change-plans-falls-due-to-fears-about-the-cost/
While concern about the environment is mounting, the willingness to invest in change is going down, the SCP said. This, the researchers say, has been boosted by the sharp rise in energy bills – some €330 a year – which became apparent in January.
‘The environment used to be a left wing pastime for people who drove an electric car and had solar panels on their roof,’ researcher Paul Dekker told Trouw. ‘But the rise in fuel bills and the decision to phase out the use of gas have brought the issue home to people on low and middle incomes… and they think it is going to cost money.’
Robertvd, on the other side of the pond, everyone gives priority to job preservation. In other words, our economy is bingo fuel and whatever’s left on saving accounts is preyed by means of ever creative tax scenarios.
It kind of smells ozone, we’re on the way to a big nasty cloud of social unrest and there seems not to be detours or alternates within reach.
Our history is seemingly a wheel. Or people wake up and vote the greens out or, when the vitrified ground cools down, contrails would be the least of tings to worry about.
Because, happens, one day or the other, UN could intervene and “politely enforce” Russia to shut down and terminate it’s oil, coal & mining industry…
Then… Is there really a “then” clause ? Hey, we’ve been there already, we still remember the consequences of a mad inhumane ideology.
330 euros a year? Californians pay that much a month.
Neat trick for an airframe rated for 1111kg max takeoff weight. I don’t want to be in their flight path when they attempt the first flight.
Indeed Sky King. 30 or so more miles NW, another heavily sponsored company tries a stretch ultralight hybrid. Think a 4 seater scaled down Trislander with only the aft prop driven by an electric motor.
In front, a Rotax + generator, 5 gallons gas tank, cooling system. And 400kg of batteries in the wings. Solar cells allover.
Take-off & climb on electric engine, cruise on gas for flight and recharging batteries, landing on electric. Go-rounds on gas + electric. No flaps / slats, fixed gear
A few thousand of those operated in self-fly pilotless mode are supposed to take care of all regional traffic.
Now even without contrails, that’s a scary movie !
Back in the day, I had a friend who was an Air Force meteorologist.
He said contrails gave him fits, because their existence and development are so difficult to predict.
On days where they were not expected, yet nonetheless formed and spread, surface temperatures would be as much as 6ºF cooler than forecast.
I know, weather isn’t climate, nor data.
I shall report to the punishment booth.
Jeeze, I’m glad that all of my forecasting billets were where the temperature was strongly controlled by the very nearby oceans, (Guam, Hawaii, and onboard ship) or in the very dry desert (Nevada). I never had problems with not hitting my temperature forecast because of cirrus. I guess that some people can’t be lucky.
Add some reflective particles to exhaust and scattering mechanism. There you go geo-engineered cooling.
Just stop removing Sulfur from Jet-A and you get some nice shiny SO2 bubbles at high altitude.
Nah…. Maintenance guys dont like what that stuff does to the hot sections.
And grumpy maintenance is realistically much fearsome than any global or local warming, altogether.
“NOTE: Any discussion of “chxxtrxxls” in this comment thread will be immediately deleted. -Anthony”
And I was just about to get out my tinfoil hat. Spoilsport. 🙁
This article triggered one of my early memories of my father: When I was about 5 or 6 years old I gave him the benefit of my vast experience and scientific observations and declared that clouds were made by aeroplanes. He gently gave me the benefit of his even vaster experience and let me know I was wrong. 🙂
This seems like a spoof. You gotta be kidding me. What’s next? Skiers are a major contributor to climate change by 2050 because of the change in albedo due to colored skiwear. I’ll write up a paper shortly.
The BS. Ever ends.
Jeff
You might need help on that project. I think an externally funded trip with our families …er…highly qualified research assistants, to 30 of the planets key ski resorts is essential in order to carry out the vital research of the coloured ski wear hypothesis.
tonyb
Every day there is a chequer pattern of contrails criss-crossing the skies over London, but they dissipate almost immediately.
It’s nice to know we’ve got air cover, I suppose.
Some years ago, visiting the UK from Johannesburg (where we rarely get contrails), my wife snapped a picture of contrails over Liverpool forming a ‘noughts and crosses’ pattern. (Maybe the ‘Pool is an airway crossing point). Anyway, seeing this, she remarked “OK, God – play the ‘X'”.
I’m going to fly as often as possible in my old age to cool the planet.
And in my old age I will sit under your contrail to stay cool.
Well let’s have a reconstruction study from 1943 to April of 1945. During that period of WW II 1,000s of allied aircraft at a time were flying from Britain and later Italy to Germany over Europe every day weather allowed. Huge formations of US B-17 and B-24 four engine bombers flying in tight formations and the fighters escorting them often left clouds of contrails during their day light raids. The British heavy bombers however, flying at night, regularly changed altitude to try and prevent leaving contrails since they were a dead giveaway to German night fighters. Then add 1,000s more 2 engine medium bombers and their escorting fighters in the last couple years of the war hitting targets in Europe.
And yes, those reciprocating engines did leave heavy contrails. And yes, the 2 engine medium bombers often flew missions high enough to leave contrails.
https://www.bing.com/images/search?q=contrails+over+germany%2c+wwii&id=66618F3E011F997B175214CD484BEFE2235F0532&FORM=IQFRBA