From Wiley-Blackwell via Eurekalert
Wartime weather records reveal impact of contrails caused by USAAF raids
Climate researchers have turned to the Allied bombing raids of the Second World War for a unique opportunity to study the effect thousands of aircraft had on the English climate at a time when civilian aviation remained rare. The study, published in the International Journal of Climatology, reveals how civilian and military records can help assess the impact of modern aviation on the climate today.
The research, led by Prof Rob MacKenzie, now at the University of Birmingham, and Prof Roger Timmis of the Environment Agency, used historical data to investigate the levels of Aircraft Induced Cloudiness (AIC) caused by the contrails of Allied bombers flying from England to targets in Europe. The team focused their research on 1943 to 1945 after the United States Army Air force (USAAF) joined the air campaign.
“Witnesses to the huge bombing formations recall that the sky was turned white by aircraft contrails,” said MacKenzie. “It was apparent to us that the Allied bombing of WW2 represented an inadvertent environmental experiment on the ability of aircraft contrails to affect the energy coming into and out of the Earth at that location.”
Aircraft can affect cloudiness by creating contrails, formed when the hot, aerosol-laden, air from aircraft engines mixes with the cold air of the upper troposphere. While some contrails disappear swiftly, others form widespread cirrus clouds which intercept both the energy coming into the planet as sunshine and that leaving the planet as infrared heat.
When the USAAF joined the Allied air campaign in 1943 it led to a huge increase in the number of planes based in East Anglia, the Midlands and the West Country. Civil aviation was rare in the 1940s, so USAAF combat missions provide a strong contrast between areas with busy skies and areas with little or no flight activity.
Today air travel is growing at an annual rate of 3-5 % for passenger aircraft and 7 % for cargo flights, but quantifiable data on the impact of AIC remains rare. In September 2001 United States airspace was closed to commercial aircraft following terrorist attacks, presenting scientists with a unique moment to study the effect of aircraft contrails in normally busy sky. Results from the 9/11 studies are controversial, but now MacKenzie and his colleagues have found an opportunity to study the opposite impact of contrails on the usually empty skies of the 1940s and have found that it is indeed possible to see the effects of AIC in surface weather observations, but that the signal is weak.
The study involved painstaking retrieval of historical records, both from the Meteorological office and from the military. The importance of weather conditions to the success of bombing missions meant that the Second World War prompted some of the most intensive weather observations ever undertaken but these are not all archived electronically.
B-17 Contrails
To distinguish the effect of aviation more clearly, the team focused on larger raids from the many flown between 1943 and 1945. They selected raids that involved over 1000 aircraft and that were followed by raid-free days with similar weather which might be used for comparison. The resulting top 20 raids revealed 11th May 1944 as the best case study.
The team found that on the morning of the 11th 1444 aircraft took off from airfields across south east England into a clear sky with few clouds. However, the contrails from these aircraft significantly suppressed the morning temperature increase across those areas which were heavily over flown.
“This is tantalising evidence that Second World War bombing raids can be used to help us understand processes affecting contemporary climate,” concluded MacKenzie. “By looking back at a time when aviation took place almost entirely in concentrated batches for military purposes, it is easier to separate the aircraft-induced factors from all the other things that affect climate.”
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Nuke says:
July 8, 2011 at 8:44 am
I found more details here:
http://www.foxnews.com/scitech/2011/07/08/did-colossal-wwii-bombing-raids-alter-weather/
Here’s an excerpt:
MacKenzie, Roger Timmis, and Annette Ryan at Lancaster, working with the Royal Air Force Museum at Hendon, went back through the records from 1943 to the war’s end in 1945. With the help of the museum staff, they were able to center on the May 11 raid. From pilot briefings, they found the planes in the morning mission produced contrails when they reached 12,000-15,000 feet, relatively low, so they concentrated on that mission. There were no missions the next few days and the weather did not change notably, providing something of a control.
Trust Fox News to get it wrong.
Table III in the paper shows that of all the raids they considered for possible study, the one they selected was the only one that had no adjacent raid-free days. So there was no ‘providing something of a control’.
Clay Marley says:
July 8, 2011 at 10:08 am
… More interesting would be to assess whether or not the entire 6 years of war lowered global temperatures as a result of the particulates and firestorms created.
http://data.giss.nasa.gov/gistemp/graphs/
According to GISS, global land-ocean mean temperature peaked in 1942 and didn’t reach the same mean temperature again until 1979.
Was the cooling between the 1942 and 1979 a result of WWII? You tell me.
Imagine what WW3 is going to do.
So if this caused cooling in they daytime, what about the night time bomber raids by the RAF, did they elevate night time temperatures, along with all the smoke reaching high levels from intense incendiarly bombing?
In which case, we should be promoting aviation, instead of taxing it. Looks like politicians got it wrong again.
.
>>PeteH
>>Are we really expected to think that they circled over the eastern UK, burning
>>up precious fuel whilst they reached the height required.
Actually they did. It was rather dangerous to climb and form formations further eastwards, as you may well get shot down. Formation flying in the daytime was the key to US operations over Germany. The British flew at night instead, in much looser formations of aircraft.
>>Add that to the fact that the bombers were petrol driven, piston engines
>>how do you equate that to sublimation from a jet engine?
Very similar. The only difference is that early piston engine aircraft often could not climb high enough to get into the contrailing layer. But clearly sometimes they did, especially later in the war with more powerful engines and better airframes.
.
“significantly suppressed the morning temperature increase” thus “it is indeed possible to see the effects of AIC in surface weather observations, but that the signal is weak.”
I think the supposed weakness is a cover-up of the up cover.
Great Article. Thanks…….Love the last sentence.
>>Tonyb
>>It is very noticeable that turbo prop contrails are a fraction of
>>those caused by jet aircaft,
Because they often do not fly high enough. Their engines are not so height-critical, relative to fuel burn, and their flights are shorter.
.
>>MCT
>>Strikes me as a bit odd that piston engined B17s, with an operating
>>height of something like 10,000 feet loaded, could be even vaguely
>>comparable to today’s jets…
The later B-17s had a max altitude of about 30,000 feet. Clue – that is why the crew used oxygen, and the waist gunners had electric suits. The British Lancasters had much better load performance, but flew lower and at night, so would not have been included in this study.
.
>>Neil
>>Further thought, tactically the “Thousand bomber raids ” would not
>>have all taken off at the same time
Actually, the idea was to swamp the German defences, and so the formations were grouped together quite tightly in time and space. Some units had to wait quite some time for the formations to gather, and could indeed get low on fuel.
.
>>DAV
>>Aircraft today typically do not fly in formation and are typically
>>separated by 5 miles horizontally. They also tend to follow the
>>same routes so the contrails while spread out do not cover the sky.
Not so. Modern commercial aircraft fly on controlled airways, but the wind aloft pushes the contrails downwind. A quartering crosswind aloft can often produce a dense mesh of contrails across the whole sky, blocking out the Sun, which is often mis-interpreted by the ignorant as being ******* trails.
.
>>Nuke
>>You are on the money here, I think. The contrails would have
>>more likely formed over Germany and German occupied territories
>>than over England.
Not so. Not only did the bombers form their formations over East Anglia – but this was a fine high pressure day, which are normally associated with easterly winds in the UK. Only at the really higher levels are the jet-streams more likely to be westerly.
.
>>Kaboom
>>Not very meaningful, considering the WW2 era planes did not reach
>>the altitudes of modern day commercial aircraft.
Most US bombers in 1945 could reach 30,000 ft. I think they went for high altitude for added safety, rather than the UKs Lancaster bombers that went lower level with larger payloads at night.
In comparison, there are many older coal-burning B737s still flying that cannot manage more than 32,000 ft, when fully laden.
.
“Civil aviation was rare in the 1940s, so USAAF combat missions provide a strong contrast between areas with busy skies and areas with little or no flight activity.”
There were few areas with little or no activity. There were airfields all over the place and often very close to each other. The amount of runway would have peaked in 1945 and has declined ever since, and continues to decline.
On one particular day in WWII there were over 25,000 allied airmen in the air at once. The largest raid had over 5000 planes in it and was a continuous stream of planes from the UK to two seperate targets. Although there are differences between a piston engine and a jet engine, a contrail is a contrail, whether generated aerodynamically or by hot exhaust. There has not been such a high concentration of aircraft over Europe since.
The current world fleet of airliners is around 20,000. The number of road vehicles globally is around 800,000,000. There is somewhere around 1000 airliners on the UK register, while there are around 30,000,000 UK road vehicles. And yet it seems all the attention is on aviation. Over time we have moved more people with fewer planes, and yet the only numbers that are discussed are the amount of people travelling by air which increases at a faster rate than the increase in flights.
Good to know the people killed on that day by the raids in Belgium, Luxemburg and a number of places in Germany served a good cause after all /sarc off
Anyway – somewhat flimsy data to base any kind of conclusion on.
So, essentially, if some 1400 and some more aircraft are said to have had a minute impact on the weather Gods of the 1940’s, . . .
In 2010 London Heathrow Airport shuffled almost 66 million people through its gates, coming and going. That’s about 181 000 per day, and if each aircraft is carrying 200 passengers thats some 900 flying apparatuses. Add Gatwick’s stats, which is a bout half, thus make up for 1400 and some aircraft in a day for only two airports in jolly England.
In 2010 there was about three million people flying though the hundred most frequent airports per day. That’s about 15,000 aircrafts that can take 200 passengers.
According to ACI Europe, who represent some 400 commercial airports in europe, they have 1.5 billion passenger throughput per year.
That’s a lot of contrails.
If we add cargo flights . . . it will just make those 1400 something look even more silly, however if those pesky 1400 and some had a minute effect, what effect does today’s tens of thousands of high flying aircraft have?
@Billy Liar:
While the link provided was at fownewd.com, the article clearly says the content was written by the Inside Science News Service.
Trust the foxnews bashers to get it wrong, perhaps?
“The team found that on the morning of the 11th (May) 1444 aircraft took off from airfields across south east England”.
The report doesn’t specify the type of aircraft, nor does it specify exactly when they took off, or at what time intervals.
US 8th AAF B17s and B24s were all based north of London. There were none in the south east of England.
http://www.303rdbg.com/h-england-map.html
Aircraft taking off during daylight on the 11th May 1944, from the south east of England, are most likely to have been twin engine tactical bombers and single engine fighter bombers, heading for France, to bomb railways, bridges and German defences prior to Operation Overlord, the invasion of France on the 6th June. These attacks would have been carried out at comparatively low levels.
In May 1944, the US 8th AAF was under the command of SHEAF, and was largley involved tactical bombing in in preparation for Overlord. These attacks would have been carried out at lower levels, due to the nature of the targets, and the fact that the Allies had established air superiority over France at this stage of the war.
Large scale strategic, high-level bombing did not resume until September 1944.
I think Profs Mackenzie and Timmis are way off target (excuse the pun).
@Ralph
I really wish I had the patent on the pulverizer for those coal-burning B737’s you were talking about.
@Rainer S
The good cause was that they weren’t able to make any more stuff to kill good guys.
I don’t know where I saw it, but there is a site that has daily images of all the contrails in the US. They cover the US in the daytime in much the same fashion as a view of all the lighting of the US at night.
That’s a lot of artificial albedo during the day and radiation emitting at night. Perhaps this is something to factor into the UHI budget.
“AshCloud says:
July 8, 2011 at 5:56 pm
“The team found that on the morning of the 11th (May) 1444 aircraft took off from airfields across south east England”.
The report doesn’t specify the type of aircraft, nor does it specify exactly when they took off, or at what time intervals.
US 8th AAF B17s and B24s were all based north of London. There were none in the south east of England.
http://www.303rdbg.com/h-england-map.html
Aircraft taking off during daylight on the 11th May 1944, from the south east of England, are most likely to have been twin engine tactical bombers and single engine fighter bombers, heading for France, to bomb railways, bridges and German defences prior to Operation Overlord, the invasion of France on the 6th June. These attacks would have been carried out at comparatively low levels.”
973 B17 and B24 heavy bombers of the 8th Air Force took off on May 11 from bases in East Anglia (which is in southeasten England) to attack four marshalling yards in northern France as part of the preparation for Overlord. The did not operate at low altitude (which was near suicidal for heavy bombers in daylight). Most of the 471 remaining missions would have been fighter escorts. As a matter of fact those 1444 missions probably apply only to the 8th AF. It seems to be too low a figure to include 9th AF tactical missions and RAF and FAA operations.
I’ve asked this question here once before on a similar thread and not got a satisfactory answer, I’ll try again. If con triails and cirrus can reflect shortwave radiation (sunlight) what do they do to longwave IR (heat), do they act like an aluminum blanket? I know water vapour absobs IR and re-emits in all directions, but do water droplets and ice particles act like difuse reflectors for IR radiation.
@ur momisugly mct
“…B17s, with an operating height of something like 10,000 feet loaded…”
I think you’ll find the standard mission cruising altitude for B17’s to be around 30,000 ft.
Brilliant! The main factor in deciding whether large bombing raids go ahead is the weather (at the departure airfields, assembly points and at the target), and some genius seeks to find a correlation between the weather and the bombers? You’ve GOT to be kidding!
The main determinant of whether an aircraft contrails or not is the meterological conditions you’re flying though. I’ve often observed in Europe that an aircraft produces ‘patches’ of contrails as it flies through what must be interleaving airmasses. I’m not sure it’s significant but the light where I live in Western Australia has a real hard-edged clarity which is very different to the diffuse light you tend to get in Europe and there’s not much high-altitude aviation over our skies…
Sort of related, the UK Met Research Flight (which did a lot of atmospheric science on “Snoopy” before NERC took it over) originated during WW2 to study contrail formation (a dead giveaway if you’re trying to sneak in unobserved). Many Battle of Britain photos of the sky show spiraling contrails from the dogfights, including the iconic picture of St. Pauls (google “St Paul’s Battle of Britain Contrails”). I reckon back in those days you could probably rely on the weather records too – I recall my ex-RAF father telling me that the RAF used to have station meteorologists who could forecast almost to the minute when fog would appear, and not a computer model in sight. Of course, that’s why so many long term weather records come from airports too, and I’d take the data before automation any day (I loved the comment someone posted here in a different thread about digitising an optical reading of a conventional thermometer – you should commercialise that!).
As to whether clouds make it hotter or colder – of course it depends where the sun is! If it’s shining through the cloud you cut the incident radiation which leads to less energy below the cloud. Otherwise they’re going to trap heat in. I very definitely believe in a greenhouse effect when we’re talking about clouds and water vapour. But is that weather or climate? it’s certainly not equilibrium 🙂
1DandyTroll says:
July 8, 2011 at 4:12 pm
“If we add cargo flights . . . it will just make those 1400 something look even more silly, however if those pesky 1400 and some had a minute effect, what effect does today’s tens of thousands of high flying aircraft have?”
I think you will find there are only two tens of thousands at the most. Also a lot of freight is sent on regular passenger services.
Dixon says:
July 9, 2011 at 7:34 am
“As to whether clouds make it hotter or colder – of course it depends where the sun is! If it’s shining through the cloud you cut the incident radiation which leads to less energy below the cloud. Otherwise they’re going to trap heat in. I very definitely believe in a greenhouse effect when we’re talking about clouds and water vapour. But is that weather or climate? it’s certainly not equilibrium :)”
Surely once the heat source (sun) is blocked/reflected then the only heat that can be trapped is residual which is less than that before being blocked. In other words cooling is retarded. I have experienced first hand high thin cloud cover cutting off my lift on a cross country glider flight. it was immediate and to put it another way, the clouds did not increase the lift / thermals, they switched them off, immediately.
>>Ascloud
>>US 8th AAF B17s and B24s were all based north of London.
>>There were none in the south east of England.
East Anglia is classed as the South East. It is certainly not the midlands, or the North East, and the Middle East is something completely different…!!
These were B-17s and B-24s taking off from the hundreds of airfields in the English Fens (East Anglia).
.
>>mike g says. July 8, 2011 at 6:17 pm
>>I really wish I had the patent on the pulverizer for those coal-burning
>>B737′s you were talking about.
Oh, I’m not sure you would. If you could see the smoke coming out of the back, it is clear that the pulveriser does not work too well. Just as well there are only a few coal-burners still operating in Africa and other locations of dubious aeronautical expertise.
.
>>dlb
>>II know water vapour absobs IR and re-emits in all directions, but do
>>water droplets and ice particles act like difuse reflectors for IR radiation.
Good question. I have not seen an experiment for this. As an observation of weather (being a weather observer), any cloud cover will stop surface temperatures falling so fast, be that water droplet cover or ice crystal cover. But this is a subjective opinion, not fact.
.
>>Stephen Skinner says: July 9, 2011 at 11:16 am
>> Also a lot of freight is sent on regular passenger services.
Not that much – passengers take to much of their own nowadays, and freighters need a dedicated hub system to sort out the freight and connect with the road system. In Europe there are now about 300 freight aircraft flying every night for the likes of TNT, DHL and Fed Ex.
.
I see a lot of speculation on this thread, when there are other sources available for some of the missing information. As always, popular articles on science often get things incorrect, but some key details are given.
http://www.tgdaily.com/sustainability-features/57098-wwii-bombing-raids-affected-british-weather
http://www.foxnews.com/scitech/2011/07/08/did-colossal-wwii-bombing-raids-alter-weather/
http://www.newscientist.com/article/dn20667-second-world-war-bombers-changed-the-weather.html
http://www.sciencedaily.com/releases/2011/07/110708084008.htm
Also, some resources on the missions on 11 May 1943. These may be harder to verify, but seem to be essentially in agreement
http://www.scottylive.com/mac_calendar/1944/May%2044%20Daily/May_11_1944.htm
THURSDAY, 11 MAY 1944
EUROPEAN THEATER OF OPERATIONS (ETO)
STRATEGIC OPERATIONS (Eighth Air Force): Mission 350: 364 B-24s and 536
fighters are dispatched to bomb marshalling yards in France; 8 B-24s and 5
fighters are lost:
1. 144 are dispatched to hit Mulhouse; 94 bomb the primary, 19 hit Belfort,
13 bomb Orleans/Bricy Airfield and 2 hit Mezidon/Pithiviers; 1 B-24 is lost,
2 damaged beyond repair and 17 damaged; 1 airman is KIA, 7 WIA and 40 MIA.
2. 74 are dispatched to Belfort; 33 bomb the primary and 24 hit Chaumont;
1 B-24 is lost.
3. 76 are dispatched to Epinal; 68 hit the primary and 1 bombs Caen
Airfield; 3 B-24s are lost.
4. 70 are dispatched to Chaumont but none bomb; 3 B-24s are lost, 1
damaged beyond repair and 30 damaged; 1 airman is WIA and 31 MIA.
Escort is provided by 147 P-38s, 188 P-47s and 201 P-51s; the P-38s claim
2-0-0 Luftwaffe aircraft on the ground, the P-47s claim 3-0-2 in the air
and 2-0-6 on the ground and the P-51s claim 3-0-0 on the ground; 2 P-4s and
3 P-51s are lost, 1 P-51 is damaged beyond repair and 2 P-38s, 6 P-47s and
2 P-51s are damaged; 5 pilots are MIA.
Mission 351: In the afternoon, 609 B-17s and 471 fighters are dispatched
to hit marshalling yards in Belgium, France, Germany and Luxembourg; 8 B-17s
and 4 fighters are lost; primary targets are Brussels/Midi (55 bomb),
Brussels (49 bomb) and Liege, Belgium (119 bomb, 2 lost); Saarbrucken (58
bomb, 5 lost), Kons Karthaus (55 bomb) and Ehrang (60 bomb, 1 lost), Germany;
and Luxembourg (53 bomb); 12 hit the secondary target at Thionville, France;
and 16 hit Volkingen, Germany; 19 hit Bettembourg, Luxembourg and 51 hit
other targets of opportunity; 8 B-17s are lost, 1 damaged beyond repair and
172 damaged; 2 airmen are KIA, 23 WIA and 83 MIA. Escort is provided by 99
P-38s, 182 Eighth and Ninth Air Force P-47s and 190 Eighth and Ninth Air
Force P-51s; the P-51s claim 11-0-4 Luftwaffe aircraft; 4 P-51s are lost,
the pilots are MIA.
Mission 352: 4 of 5 B-17s drop 2.4 million leaflets over Denmark; 2
airmen are KIA and 3 WIA.
4 B-24s are dispatched on CARPETBAGGER missions.
850th Bombardment Squadron (Heavy), VIII Air Force Composite Command
attached to 801st Bombardment Group (Provisional), moves from Eye to
Cheddington, England with B-24s; the squadron is flying CARPETBAGGER
missions.
TACTICAL OPERATIONS (Ninth Air Force): 330+ B-26s attack airfields at
Beaumont-le-Roger and Cormeilles-en-Vexin and marshalling yard at Mezieres/
Charleville, France and Aerschot, Belgium. Bad visibility and failure to
rendezvous with fighters cause 100+ aborts. This is start of Ninth Air
Force’s participation in AAF pre-invasion offensive against airfields.
14th Liaison Squadron, XIX Tactical Air Command attached to Third Army,
moves from Alderley Edge to Knutsford, England with L-5s; first mission is
in Jul 44.
http://www.8thafhs.org/combat1944a.htm
THURSDAY, 11 MAY 1944
STRATEGIC OPERATIONS (Eighth Air Force): Mission 350: 364 B-24s and 536 fighters are dispatched to bomb marshalling yards in France; 8 B-24s and 5 fighters are lost:
1. 144 are dispatched to hit Mulhouse; 94 bomb the primary, 19 hit Belfort, 13 bomb Orleans/Bricy Airfield and 2 hit Mezidon/Pithiviers; 1 B-24 is lost, 2 damaged beyond repair and 17 damaged; 1 airman is KIA, 7 WIA and 40 MIA.
2. 74 are dispatched to Belfort; 33 bomb the primary and 24 hit Chaumont; 1 B-24 is lost.
3. 76 are dispatched to Epinal; 68 hit the primary and 1 bombs Caen Airfield; 3 B-24s are lost.
4. 70 are dispatched to Chaumont but none bomb; 3 B-24s are lost, 1 damaged beyond repair and 30 damaged; 1 airman is WIA and 31 MIA.
Escort is provided by 147 P-38s, 188 P-47s and 201 P-51s; the P-38s claim 2-0-0 Luftwaffe aircraft on the ground, the P-47s claim 3-0-2 in the air and 2-0-6 on the ground and the P-51s claim 3-0-0 on the ground; 2 P-4s and 3 P-51s are lost, 1 P-51 is damaged beyond repair and 2 P-38s, 6 P-47s and 2 P-51s are damaged; 5 pilots are MIA.
Mission 351: In the afternoon, 609 B-17s and 471 fighters are dispatched to hit marshalling yards in Belgium, France, Germany and Luxembourg; 8 B-17s and 4 fighters are lost; primary targets are Brussels/Midi (55 bomb), Brussels (49 bomb) and Liege, Belgium (119 bomb, 2 lost); Saarbrucken (58 bomb, 5 lost), Kons Karthaus (55 bomb) and Ehrang (60 bomb, 1 lost), Germany; and Luxembourg (53 bomb); 12 hit the secondary target at Thionville, France; and 16 hit Volkingen, Germany; 19 hit Bettembourg, Luxembourg and 51 hit other targets of opportunity; 8 B-17s are lost, 1 damaged beyond repair and 172 damaged; 2 airmen are KIA, 23 WIA and 83 MIA. Escort is provided by 99 P-38s, 182 Eighth and Ninth Air Force P-47s and 190 Eighth and Ninth Air Force P-51s; the P-51s claim 11-0-4 Luftwaffe aircraft; 4 P-51s are lost, the pilots are MIA.
Mission 352: 4 of 5 B-17s drop 2.4 million leaflets over Denmark; 2 airmen are KIA and 3 WIA.
4 B-24s are dispatched on CARPETBAGGER missions.
850th Bombardment Squadron (Heavy), VIII Air Force Composite Command attached to 801st Bombardment Group (Provisional), moves from Eye to Cheddington, England with B-24s; the squadron is flying CARPETBAGGER missions.