Debunk Global Warming can reduce the number of Persistent Contrails

[George B]

Debunk Global Warming can reduce the number of Persistent Contrails and Contrail Induced Cirrus Clouds

Recent discussions of climate change (MSU Temperature Record, ACIA) have highlighted the fact that the stratosphere is cooling while the lower atmosphere (troposphere) and surface appear to be warming. The stratosphere lies roughly 12 to 50 km above the surface and is marked by a temperature profile that increases with height. This is due to the absorbtion by ozone of the sun's UV radiation and is in sharp contrast to the lower atmosphere. There it generally gets colder as you go higher due to the expansion of gases as the pressure decreases. Technically, the stratosphere has a negative 'lapse rate' (temperature increases with height), while the lower atmosphere's lapse rate is positive.
http://www.realclimate.org/

Recent analyses of temperature trends in the lower and mid- troposphere (between about 2,500 and 26,000 ft.) using both satellite and radiosonde (weather balloon) data show warming rates that are similar to those observed for surface air temperatures. These warming rates are consistent with their uncertainties and these analyses reconcile a discrepancy between warming rates noted on the IPCC Third Assessment Report (U.S. Climate Change Science Plan Synthesis and Assessment Report 1.1).


An enhanced greenhouse effect is expected to cause cooling in higher parts of the atmosphere because the increased "blanketing" effect in the lower atmosphere holds in more heat, allowing less to reach the upper atmosphere. Cooling of the lower stratosphere (about 49,000-79,500 ft.) since 1979 is shown by both satellite Microwave Sounding Unit and radiosonde data (see previous figure), but is larger in the radiosonde data likely due to uncorrected errors in the radiosonde data.
http://www.ncdc.noaa.gov/

Is The Stratosphere Responsible For Global Warming?

Nataliya Kilifarska of the National Institute of Geophysics, Geodesy and Geography, in Sofia, Bulgaria, presents a powerful analysis that confirms a strong relationship between stratospheric ozone and land air temperature.
http://junkscience.com/2012/05/17/is...lobal-warming/


She says that this highly significant relation raises the question about the nature of the influence, and suggests that it operates through control over the temperature and humidity in the upper troposphere/lower stratosphere by ozone variations. The ozone variability itself is initiated by variations in Galactic Cosmic Ray (GCR) intensity, which produces O3 at these levels. GCRs are in turn mediated by the Sun. An important point is that the high effectiveness of this mechanism is due to the fact that small fluctuations of the H2O vapour (in the most arid regions of the troposphere) influences the radiation balance of Earth in a highly non-linear way meaning small changes in the Sun results in a big change in Earth's temperature.


Ken Minschwaner, a physicist at the New Mexico Institute of Mining and Technology, Socorro, N.M., and Andrew Dessler, a researcher with the University of Maryland, College Park, and NASA's Goddard Space Flight Center, Greenbelt, Md, did the study. It is in the March 15 issue of the American Meteorological Society's Journal of Climate. The researchers used data on water vapor in the upper troposphere (10-14 km or 6-9 miles altitude) from NASA's Upper Atmosphere Research Satellite (UARS).
Their work verified water vapor is increasing in the atmosphere as the surface warms. They found the increases in water vapor were not as high as many climate-forecasting computer models have assumed. "Our study confirms the existence of a positive water vapor feedback in the atmosphere, but it may be weaker than we expected," Minschwaner said.
http://earthobservatory.nasa.gov/New...w.php?id=24432

 

[George B]

Seems research indicates GW is increasing the temperature in the Troposphere and reducing the temperature in the stratosphere while increasing humidity in both . . . seems this could effect contrail formation and persistence . . .

 

[MikeC]

Where does it say that it will specifically can not reduce the number of Persistent Contrails? As far as I can see from what you have posted the actual effects on contrails are not specified.

 

[George B]

Where does it say that it will specifically can not reduce the number of Persistent Contrails? As far as I can see from what you have posted the actual effects on contrails are not specified.

This might help . . . Dr Minnis comments/responses are in red . . .

From: Minnis, Patrick (LARC-E302) [mailto:p.minnis@nasa.gov]
Sent: Saturday, November 10, 2012 11:01 PM
To: George B
Subject: Re: Persistent Contrails and Global Warming

Dear Mr. B,

I will try to answer your question below.

Patrick

On Nov 10, 2012, at 2:35 PM, George Berberich wrote:


Dr Minnis


Question . . .Dr Minnis . . . Can one say that global warming is potentially responsible for \
an increase in persistent contrails and contrail induced cirrus cloud banks?


I doubt that slightly higher temperatures due to climate change are responsible for an increase in persistent contrails and induced cirrus.
Higher temperatures in the troposphere would raise the altitude necessary for contrail formation, so that there would likely be slightly fewer contrails rather than more.

If so, what percentage could it represent of the total of the following factors?

1) Increased number and frequency of flights overall at altitudes above 30,000 feet
2) Larger and more powerful engines
3) More efficient engines
4) Global Warming



If there is more moisture in the high troposphere and lower stratosphere because of warming . . . and the temperature of the upper troposphere is warmer and the stratosphere is colder . . . so can this means .. . more persistent contrails in the stratosphere but fewer in the troposphere. . . ? Seems very negligible to me . . . I have never seen any publication which included the above discussion or speculation about the persistence of contrails based on global warming . . .see research cites below . . .


Persistent contrails rarely ever form in the stratosphere because it is too dry. A slight increase in humidity will not be sufficient to change this negligible frequency. More moisture in the upper troposphere could possibly lead to thicker contrails, but not more of them.



Thanks for your time

http://www.realclimate.org/index.php...osphere-warms/

http://www.ncdc.noaa.gov/cmb-faq/globalwarming.html
http://junkscience.com/2012/05/17/is...lobal-warming/

http://earthobservatory.nasa.gov/New...w.php?id=24432

Sent from my iPad

Yours Truly

George B
Colonel USAF Retired

***************************************************************************************
Patrick Minnis, PhD
MS 420
NASA Langley Research Center
Hampton, VA, USA 23681-0001
phone: 757-864-5671 fax: 757-864-7996 email: Patrick.Minnis-1@nasa.gov
homepage: http://www-pm.larc.nasa.gov
"humilitas est veritas"
*****************************************************************************************

 

[Mick West]

I would have though that more moisture in the upper troposphere would lead to at least larger volumes of ice-supersaturated air, and hence slightly more contrails, not just thicker contrails.

Still, there are multiple interconnected variables here, with various types of feedback, so it's quite difficult to say what the net effect would be on contrail frequency

 

[George B]

I would have though that more moisture in the upper troposphere would lead to at least larger volumes of ice-supersaturated air, and hence slightly more contrails, not just thicker contrails.

I would have thought that as well . . . however, I think the point is because of global warming the warmer temperatures reaching higher into the troposphere reduces or shrinks the optimal air potential to produce supersaturated air for ice more than the increased humidity would increase the potential for supersaturated air . . . so increased temperatures at altitude wins over more humidity . . .

 

[Mick West]

I would have thought that as well . . . however, I think the point is because of global warming the warmer temperatures reaching higher into the troposphere reduces or shrinks the optimal air potential to produce supersaturated air for ice more than the increased humidity would increase the potential for supersaturated air . . . so increased temperatures at altitude wins over more humidity . . .

That depends on the frequency of flights through various altitudes.

 

[George B]

That depends on the frequency of flights through various altitudes.

I can't disagree (in fact, I have always said contrail avoidance is very possible) . . . however, I think as a general and broad observation, Dr Minnis was saying . . . because of global warming air traffic will (based on existing filght patterns and in the foreseeable future) as a general rule may (slightly) reduce the potential for persistent contrails, not increase them . . .