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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I bet the conclusion was reached with a V and V climate model. Right?
One point to note, is that the massed bomber raids concentrated the aircraft and thus their contrails in a discrete area. Civilian aviation is far more dispersed by the time the planes reach an altitude where contrails can form.
Also, is there a difference between the exhaust gases produced by radial piston engines & jets? Will this lead to differing properties in the vapour trails formed?
I think there’s a lot to learn from military archives from WWII.
Just remember that the Nazi’s were able to infiltrate a few patrols in the Arctic (Svalbard, Iceland, Greenland), tasked to operate some meteo stations to collect data for the planning of military operations; the last Nazi station surrendered on September, 1945!
And the same was made, on a bigger scale, by the Allies.
After 1945, we have the full time lenght of the Cold War, with the planning of naval operations in the GIUK (Greenland, Iceland, United Kingdom) theatre of operations, the NORAD and so on.
Well, IMHO, I think there’s still a LOT to discover and to learn from military archives…
Just my 2 cents
Dario
I remember seeing a program about the 3 days after 9/11 when all planes were grounded.
A guy at a weather station somewhere in the U.S. found that the sky got quite clear without planes flying. He checked the measurements and found that the misty layer the plans produce block some of the incoming sunlight in the day time. The misty layer blocks some of the outgoing heat in the night time from escaping into space.
The explanation was that with the layer the daytime temperature is a bit cooler and the night time temperature is a bit warmer. Without the layer the daytime temperature is a bit warmer and the night time temperature is a bit cooler.
To be honest, even as a child I realized that a cloud free sky makes the daytime warmer and the night time cooler. If you have clouds in the sky the sun is blocked and it doesn’t get too warm and in the night time the clouds will keep it a bit warmer.
Why do people draw the curtains or close the shutters in the day and open the windows in the night?
“As is our stated blog policy, no discussions or linkages to discussion of chemtrails will be permitted. Grousing about it won’t change anything.”
An attempt to keep the comments stream slender and sylphlike ?
On a serious note 1944 was a curious year for weather. There were summer storms which delayed “Overlord” and destroyed the US “mulberry” installation. And an early and harsh winter which contributed to a severe famine in the Netherlands. Is there any recognition of this by the papers authors?
REPLY: From experience I have leaned the topic always degrades into a pointless shouting match, requiring huge amounts of time to moderate. I simply don’t have the time nor the will to waste my time (or the time of other moderators) on trying. There are plenty of other places to discuss this issue.
BTW, lest someone accuse me of being draconian, take a moment to read the comments policy over at Greg Laden’s science blog.
http://scienceblogs.com/gregladen/about.php (see Nefarious Commenting Policy midway down)
That’s a real eye opener. – Anthony
However, the contrails from these aircraft significantly suppressed the morning temperature increase across those areas which were heavily over flown.
Not a very scientific study as again there is no knowing what the temperature would have been if the aircraft had not flown. Furthermore, for contrails to form, the air at the aircraft levels has to be supersaturated with water vapor which everyone knows is many times more effective at absorbing infrared than CO2. However, it is interesting that the statement above is diametrically opposed to the NASA Langley ‘research’ that showed that temperatures were cooler when aircraft were not flying and contrailing due to the post 9/11 flying ban,
Nevertheless, as any holidaymaker will tell you if there is a layer of cirrus the beach is not as hot.
What an interesting take on climate.
We live near an airport from which both jet and turbo prop aircraft fly. It is very noticeable that turbo prop contrails are a fraction of those caised by jet aircaft, which of course didn’t mostly come into operation during the time scale mentioned. That might affect calculations.
However, much more interestng is that GS Callendar-yes that one- made a considerable contribution to the war effort by creating the means to keep fog laden British airfields clear. He did this-ironically- by burning millions of gallons of oil which drove the fog away. It would be interesting to know if this had any effect.
tonyb
In chasing up information on the WW2 contrails, I found that the bomber pilots were aware that the Luftwaffe fighter pilots use contrails to track and attack incoming bombing missions.
On record are some that flew at different altitudes to avoid the conditions that made them vulnerable to this type of attack.
I won’t mention I was using it to debunk —–
Somehow, I just knew “East Anglia” would worm its way into this somewhere! It’s interesting but I don’t buy it just for now 🙂
Alas, no mention of the tragic & horrific loss of life in that hectic period from all the lead poisoning in the high-level & low-level atmosphere. You know, the .303, .30, the 50 calibre, the 20mm, 30mm, & 40mm cannon, & fire from the ground type of lead poisoning, the sort that has a somewhat instantaneous hazzard for human health. It all must have fallen to the ground at some stage! What about all the sulphur from the cordite? Did that not also have an effect on atmospherics close to the ground & in the air? What about all that pollution from sinking oil tankers burning away for hours on end at times, & in storage facilities on land in Western Europe, Eastern Europe, Asia & the Phillipines, etc. What about adding in Pearl Harbour, based next to an active volcano, (although any natural pollution was outshone by that from humans on that momentously tragic day) now quaintly referred to as “environmental terrorism”. How much do volcanoes put up in the atmosphere in the way of particulates, sulphur & Co2 in comparison? Iceland, Chile, Indonesia, to mention three of late! Just a thought.
Perhaps the days on which bombing raids were executed were not selected independently of the weather.
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.
So the clear first experimental signal about aircraft contrails is that they suppress (i.e. make lower) temperatures. As one would expect from clouds – increasing reflection of sunlight.
Also as one would expect, the exact opposite of the AGW orthodoxy that aircraft promote climate warming.
Why do clouds look grey from underneath and white from above? Because they reflect more radiation from above than from below.
Or try this one: what radiates more energy, the sun or the earth (as measured in the troposphere-stratosphere)? (Clue: its the sun.)
Once again the attack against civil aviation from the CAGW movement, on supposedly environmental grounds, is shown to be nothing more than the pursuit of a class war, anarchist-anti-capitalist agenda and totally dislocated from any scientific reality.
ZOMG ear-worm warning! Do not think of the theme song from 12-O’clock High! If unfamiliar do not repeat, do not Google.
Count me sceptic on that one, I am more puzzled by the 1995-2005 period.
http://www.vukcevic.talktalk.net/CET-ann.htm
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…
Last spring, air travel over Western Europe was shut down for 2-3 weeks. That should be an opportunity for someone interested in pursuing this line.
No links to the study or associated data??
“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 others didn’t show the desired results??? Two years of data and they come up with one day???
Clever idea for the study. I’d like to see more detail.
A bit of searching for International Journal of Climatology found this link for those who may want to read more in detail.
http://onlinelibrary.wiley.com/doi/10.1002/joc.2392/full
World War II contrails: a case study of aviation-induced cloudiness
A. C. Ryan
A. R. MacKenzie
S. Watkins
R. Timmis
Article first published online: 8 JUL 2011
DOI: 10.1002/joc.2392
Copyright © 2011 Royal Meteorological Society
I think perhaps the effeect of the bombs they dropped would have had more effect on climate than the contrails … just musing.
Hey, contrails lead to cooling! Let’s all fly around the world to save the planet 🙂 Maybe Greenpeace can sponsor my next trip to Australia.
O’ which we see b’spoke ‘n sea o’ willy nilly:
NYCToDAY1: http://oi52.tinypic.com/n5sk6u.jpg
NYCToDAY2: http://oi54.tinypic.com/vhry4j.jpg
NYCoODAY3: http://oi55.tinypic.com/2781g.j
NYCToDAY4: http://oi55.tinypic.com/2dh5f60.jpg
NYCToDay5: http://oi54.tinypic.com/2v9c0hx.jpg
NYCToDay6: http://oi51.tinypic.com/2nur61g.jpg
NYCToDay7: http://oi54.tinypic.com/2yzla1x.jpg
Raphael: http://www.victorianweb.org/painting/italian/raphael1.jpg
Just a couple of small points. Most of these contrails occurred over the European mainland and not over England as often the planes were still climbing or descending at the end of the raid and so less likely to generate contrails. Also the planes would be taking off from diverse locations and meeting up at altitude over the sea to the east of England resulting in contrails being more widely dispersed than this summary seems to suggest.
Further thought, tactically the “Thousand bomber raids ” would not have all taken off at the same time or flown the same route but would have been dispersed to a variety of different flight plans to force defending fighters to cover as much sky as possible and stop the enemy from concentrating their forces with much greater effect.
The “thousand bomber raids” were only intended to put a thousand bombers in waves over the target, not fly them as a single body to it. From that I would have expected any contrails to be equally dispersed and should then question the effects observed.
Wasn’t there an extensive study done when concorde operation was first being studied?
Well we know SOMETHING caused the eruption of Vesuvius….
1444 aircraft is a LOT of aircraft. Look at the photo with the contrails from 10 aircraft in formation. How this applies today is problematic. Aircraft 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.