From Dr. Roger Pielke Senior: (with apologies to Tattoo)
There is a news article on March 29 2011 from Rueters titled
The text begins with [highlight added]
“Aircraft condensation trails criss-crossing the sky may be warming the planet on a normal day more than the carbon dioxide emitted by all planes since the Wright Brothers’ first flight in 1903, a study said on Tuesday.”
Another excerpt reads
“The study, by experts at the DLR German Aerospace Center, estimated that the net warming effect for the Earth of contrails and related cirrus clouds at any one time was 31 milliwatts per square meter, more than the warming effect of accumulated CO2 from aviation of 28 milliwatts.”
If correct, this is a remarkable finding with respect to contrails as a climate forcing. It also shows that as we study the climate system, we find it is affected by a wider diversity of human climate forcings than concluded by the IPCC. The human effect on the climate system is not dominated by CO2 and a few other greenhouse gases.
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Just a firm reminder, any comment mentioning, referring to, or paraphrasing anything to do with “chemtrails” will be automatically sent to the bit bucket. – Anthony
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Transport? Please see the EUSSR Master Plan for who can travel, when and where and by what means in the White Paper recently published.
It is ponderous in the extreme and couched in best obfuscatory language but it does show how Socialism is taking over Europe.
http://ec.europa.eu/transport/strategies/doc/2011_white_paper/white_paper_com%282011%29_144_en.pdf
Let’s hope it’s true. With the sun apparently entering a quiescent phase, we’re going to need all the warming we can get.
Does it never end ? The water vapor that is already in the atmosphere; if it condenses to form a contrail, it will still absorb solar energy just as it did as a vapor; and in addition to that it will wide angle scatter additional sunlight; which we often refer incorrectly to as “reflection”, so about half of that “reflected sunlight will head up to space, and only about half will head down; so the amount of sunlight reaching the surface MUST decrease, which most people would call acooling influence. And the higher those contrails are the smaller solid angle they subtend at the surface, so the amount of LWIR radiation from the surface, that they intercept goes down with cloud altitude (increase).
The jet engine exhaust itself, adds further moisture to the upper atmosphere, which also may form more clouds, and also block more incoming solar energy. Even the extra CO2 emitted by the engine, will absorb some incoming solar radiation in the near IR range 2-4 microns. Why do they keep pushing this positive cloud feedback notion.
The surface irradiation from LWIR capture and re-emission by high clouds falls as the inverse fourth power of the cloud height, and also by cosine to the eighth power of obliquity angle. The highly colimated incoming sunlight (0.5 deg divergence) gets directly blocked proportionate to the cloud area; in addition to the wide angle scattering.
The first letter to an editor I wrote was about this issue. The date would have been 1970 or a bit earlier as the USA’s move toward a SST was halted by Senator William Proxmire and others at that time. A magazine, Popular Science (or some such), ran an article about how clean the SST would be because it would mostly put only H2O and CO2 into the very highest levels. My comment was that even though the two molecules were thought of as non-toxic, they should still be considered as detrimental if large amounts were put into a portion of the atmosphere where they did not currently exist.
At that time there was some concern about a coming Ice Age. It was our good fortune the SST was defeated and the Ice Age was averted by keeping these molecules in the lower atmosphere – and they helped with the, so called, green revolution, also. (Don’t respond to this last bit. It’s called humor.)
Serfs shalt not own cars….
Surf shalt not fly in planes…
Serf shalt not use electricity…
Serfs shalt be irradiated…
Someone asked about this:
“The IPCC estimates that aviation today is responsible for 2 percent of global CO2 emissions with a total climate change impact of 3 percent. These figures have remained largely unchanged over the last two decades, despite the growth of air traffic.”
— http://www.nytimes.com/2007/09/20/opinion/20iht-edbisi.1.7583290.html
No, no, no, if I remember right, during the few days after 9/11 the daytime temps didn’t change but night time temps did. They went down. Low level and cumulus clouds reflect incoming insolation and lower temps, but contrails, cirrus and contrail induced cirrus have a net warming effect. We’ve known all this for a long time already. Nothing new here, move along folks.
Roger Pielke Sr. says:
This is a bit of a somewhat biased interpretation of the finding. 31 mw/m^2 is to be compared to the current forcing due to the CO2 levels elevated from pre-industrial levels of ~1.7 W/m^2. So, we are talking about an effect that is ~50 times smaller than the effect of CO2. I am a bit surprised that Roger, who surely knows these relative values, didn’t think to provide this context!
Also, if you go the Reuters link, the authors of the study also provided this additional context:
As for those who are wondering why contrails cause more warming than cooling: In general, thin high clouds have a larger effect on reducing outward terrestrial radiation than on reducing incoming solar radiation…although it can get complicated in regards to location [e.g., tropics or mid-latitudes], height, and optical depth of the clouds. In fact, skeptic Richard Lindzen’s proposed “iris effect” ( http://en.wikipedia.org/wiki/Iris_hypothesis ) made the claim that a warming climate leads to a REDUCTION of such cirrus clouds and thus to a negative feedback.
George E. Smith, or anyone else who might know,
Do contrails or clouds send any more IR radiation in an earthward direction than the watervapour that formed them prior to condensation?
Zeppelins do not leave contrails, do they?
Maybe they want to revive the zeppelin industry. 🙂
During WWII there were hundreds of planes flying in formations leaving massive contrails.
Is there any data showing any temperature anomalies at that time?
So what would be the contrail temperature feedbacks for a continent such as Australia or The Antarctic?
Hmmmmmmm….. Yessss……….. I think I’m beginning to see the ‘Con Trail’ effect and how the ‘Con Trail’ can be used to support additional claims of Man Made Global Warming. Yeesssss, it’s getting clearer……………….
This ‘Con Trail’ will be very similar to other Con Trails, like the Mann made ‘Hide the Decline’, etc……
Personally, I think they increase the albedo, therefore would have a cooling effect.
I think we have a fallacy of false precision here. The incoming radiation from the Sun is about 1360 Watts/m**2. They claim an effect of some 30 milliWatts. This is some 5 orders of magnitude less; and this has been “measured” over 100 years?
They jest; they digest; they fart.
The map is fascinating. At first I wondered why so many flights were starting and ending in the middle of the Atlantic! Then I realized it’s like the old trick of rubbing a pencil over paper to show the contours of an engraving. The trails show where vapor is available for condensation.
“”””” dlb says:
March 31, 2011 at 4:35 pm
George E. Smith, or anyone else who might know,
Do contrails or clouds send any more IR radiation in an earthward direction than the watervapour that formed them prior to condensation? “””””
How could they ? As I already explained above, IN ADDITION to continuing to absorb INCOMING SOLAR RADIATION ENERGY, cloud water droplets (if still liquid) make very nice (but aberrated) focussing lenses, and the total sunbeam that strikes a single drop, refracts that beam into an expanding cone of light (after coming to a “focus”) that spreads into a complete hemisphere of light. Now the amount that refracts beyond about 50 degrees is not large; but remember that is the result of single drop. That expanding cone of rays, will hit other droplets, and in no time you will have a completely diffuse essentially isotropic light distribution; only half of which can ever reach the ground, and that only in a very diffused spread.
Now if the water droplets freeze, which is more likely at jet plane altitudes, the ice crystals, are not going to make good lenses, like a smooth droplet, but they will still scatter the light over large angles.
You may have noticed that a fresh contrail, will either quickly evaporate, which presumably is a result of the humidity not being all that high up there, so the exhaust water vapor is still not enough to saturate the humidity; or else, the trails persist, and actually start to grow.
I have postulated, that as a result of the additional sunlight blocking underneath the trail/cloud (as seen by the sun); the air immediately adjacent to the lcoud undergoes further cooling due to the reduction in local sunlight, and that will mean the dew point gets closer, so more condensation can take place; and that results in further cooling.
I have watched these trails and clouds for hours on end, and observed, how they grow from their underside; when the humidity conditions are right. I have watched a handfull of trails over San Jose CA, eventually spread and thicken into a complete cloud layer, by late afternoon, from a handful of narrow streaks earlier in the day. But I also have seen them just evaporate, and in just a very few minutes, so you can still see the plane laying down the trail; but it peters out quickly. Just not cold enough or humid enough up there for it to grow.
Now a cloud out on the horizon, being hit sideways on by grazing sunlight, is certainly going to scatter some sunlight that otherwise would have gone straight on by, and back out into space, so that it now reaches the ground. But for the same reason. Grazing incidence sunlight that is headed for collision with the ground out on the horizon, can now be refracted into an upward direction, so that sunlight that otherwise would have reached the ground, will now be lost to space. I believe the result is a wash. I haven’t been able to explain why such horizontal cloud scattering would favor adding to the ground energy over subtracting; but the point is that any solar energy that gets captured by either H2O vapor or liquid (or solid) or any CO2 for that matter, will then becoem a source of LWIR emission that is isotropic, so only half of it can reach the ground; so that is a NET LOSS of solar energy.
More importantly the fraction of the captured incoming solar energy that does ultimately reach the ground, does so at LWIR wavelengths, and instead of propagating deeply into the deep oceans, as direct sunlight does, it is absorbed in the top few microns of the surface, which will lead to increased and prompt evaporation; and that is going to remove a lot of latent heat energy from the oceans, and put more water vapor into the atmosphere, where convection can transport that energy to higher altitudes to eventually be lost.
Now I don’t deny, that to the extent that surface emitted LWIR is captured by increased CO2 and H2O in the atmosphere, that will produce a warming trend just due to the delay in escape of that energy; but I’m not convinced that is a large effect because of the fact that any returned LWIR from the atmosphere, gets absorbed in the thinnest water surface; whereas solar spectrum energy goes deep in the oceans.
AWGs new motto, yes we con. More warm/cold and pleas for more tax dollars.
I think any tax and spend politician worth their well-earned title looks at those trails and things $$$$$$$$$$$$$. Therefore, they must paint them in a bad light in order to have a chance at putting a tax on it. Looks like their already on step one.
I tracked down the abstract at Nature Climate Science:
“Here we use a global climate model that captures the whole life cycle of these man-made clouds to simulate their global coverage, as well as the changes in natural cloudiness that they induce. We show that the radiative forcing associated with contrail cirrus as a whole is about nine times larger than that from line-shaped contrails alone. ”
http://www.nature.com/nclimate/journal/v1/n1/full/nclimate1068.html
Post modern science at its best. We learn what the modeler’s assumptions were. The world is assumed to be inscrutable.
Thanks George, I understand what you are saying but I’m thinking about what is happening at night when there is no sunlight hitting the clouds. Does the outgoing LW radiation from the earths surface react with condensed water and ice differently to the vapour stage? i.e. are the clouds reflecting or refracting LW radiation a bit like the way foil is used as an insulating medium.
The water vapor is already there! As stated above. condensed yes. That ‘photo’
is misleading also stated above. you take a dry, warm, airmass you get very little
contrail formation. January 29th is the worst time to do this especially with this
cold,WET winter that was from coast to coast.
I call Bravo Sierra.
Regarding 9/11 and contrails, according to this article, Dr. David Travis at the University of Wisconsin compared the temperatures for the three days after 9/11 to other days when planes were flying and concluded that “average daily temperature range between highs and lows was 1.1 degrees C higher during September 11-14 (shown graphically in Figure 2) compared to September 8-11 and September 14-17 with normal air traffic.”
http://www.tech-know.eu/uploads/Greenhouse_Gases_Cool_Earth.pdf
However, this paper concluded that “the unusual temperatures on 11 and 12 September were a result of a particularly clear weather pattern, not a lack of jet contrails. Furthermore, the average diurnal temperature range for 11 to 14 September 2001 was only slightly above average, but well below what should have occurred based upon air masses present across the country. There is no doubt that contrails have some effect on the regional, hemispheric, and global climate system (Penner et al. 1999), but we conclude that the magnitude of this effect was overestimated by the Travis et al. (2002) study.”
http://www.ottokinne.de/articles/cr2004/26/c026p001.pdf
According to the abstract for this paper, “None of the results herein indicates a significant impact of contrails on reducing the DTR. Hence, it is concluded that the respective hypothesis as derived from the 3-day aviation-free period over the United States lacks the required statistical backing.” However, it uses models.
http://journals.ametsoc.org/doi/abs/10.1175/2008JCLI2255.1
If the contrail casts a shadow (however diffuse) it’s cooling. Same with any cloud. They only warm when there’s no significant DSW or DLW to block. In such cases, they’re “shadowing” outer space and the universe from Earth’s OLW.
This study brought to you by Amtrak.
This stuff about contrails has got to be true.
In fact they had so many contrails on one particular air raid during WWII that
Dresden caught on fire. I think that Tokyo had a similar fate due to contrails.
I remember that right after 9/11, when all the planes were grounded, there was a significant decrease in night time temperature. From Science Daily: “The change in the temperature difference was plus 1.1 degree Celsius, equal to plus 2 degrees Fahrenheit, above the 30-year long-term mean diurnal temperature range. The researchers compared the temperature ranges on these three days to those of the three days directly before Sept. 11 and the three days after Sept. 14, finding that the days before and after were similar, but that the three days in question differed by 1.8 degrees Celsius or 3.2 degrees Fahrenheit.”