For anyone interested in real contrail science (not you, code 3, don’t even dare to look at this link ),

Around 17% of the Earth is covered with air masses which are ice-supersaturated and cold enough so that persistent contrails form when aircraft fly in these region. . .

Several recent studies show that supersaturation with respect to ice is very common in the upper troposphere (K. Gierens, E. Jensen, J. Ovarlez et al.), see Figure 7. In the Arctic winter, supersaturation occurs even in the lowermost stratosphere due to the extremely low temperatures in this region. Also the tropical upper troposphere is often ice supersaturated. Cirrus clouds rarely extend more than 1 km above the tropopause (E. Jensen et al.). Large ice supersaturation also occurs within cirrus clouds (J. Ovarlez et al.).

Abstract. Data from three years of MOZAIC measurements made it possible to determine a distribution law for the relative humidity in the upper troposphere and lower stratosphere. Data amounting to 13.5% of the total were obtained in regions with ice supersaturation. Troposphere and stratosphere are distinguished by an ozone concentration of 130 ppbv as threshold. The probability of measuring a certain amount of ice supersaturation in the troposphere decreases exponentially with the degree of ice supersaturation. The probability of measuring a certain relative humidity in the stratosphere (both with respect to water and ice) decreases exponentially with the relative humidity. A stochastic model that naturally leads to the exponential distribution is provided. Mean supersaturation in the troposphere is about 15%, whereas ice nucleation requires 30% supersaturation on the average. This explains the frequency of regions in which aircraft induce persistent contrails but which are otherwise free of clouds. Ice supersaturated regions are 3-4 K colder and contain more than 50% more vapour than other regions in the upper troposphere. The stratospheric air masses sampled are dry, as expected, having mean relative humidity over water of 12% and over ice of 23%, respectively. However, 2% of the stratospheric data indicate ice supersaturation. As the MOZAIC measurements have been obtained on commercial flights mainly between Europe and North America, the data do not provide a complete global picture, but the exponential character of the distribution laws found is probably valid globally. Since water vapour is the most important greenhouse gas and since it might enhance the anthropogenic greenhouse effects via positive feedback mechanisms, it is important to represent its distribution correctly in climate models. The discovery of the distribution law of the relative humidity makes possible simple tests to show whether the hydrological cycle in climate models is represented in an adequate way or not.

Abstract
We present an investigation of upper tropospheric humidity profiles measured with a standard radiosonde, the Vaisala RS80-A, and a commercial frost-point hygrometer, the Snow White. Modifications to the Snow White, to enable the mirror reflectivity and Peltier cooling current to be monitored during flight, were found to be necessary to determine when the instrument was functioning correctly; a further modification to prevent hydrometeors entering the inlet was also implemented. From 23 combined flights of an ozonesonde, radiosonde and Snow White between September 2001 and July 2002, clear agreement was found between the two humidity sensors, with a mean di_erence of <2% in relative humidity from 2 to 10 km, and 2.2% between 10 and 13 km. This agreement required a correction to the radiosonde humidity, as described by Miloshevich et al. (2001). Using this result, the dataset of 324 ozonesonde/RS80-A profiles measured from Aberystwyth between 1991 and 2002 was examined to derive statistics for the distribution of water vapour and ozone. Supersaturation with respect to ice was frequently seen at the higher levels – 24% of the time in winter between 8 and 10 km. The fairly uniform distribution of relative humidity persisted to 120% in winter, but decreased rapidly above 100% in summer.

Cloud-free ice-supersaturated (with respect to ice) air masses have been detected by various types of observations. Such regions have been termed “ice-supersaturated regions” (ISSRs) (Gierens et al. 1999). A good marker of ISSR is persistent condensation trails (contrails) when the sky is otherwise free of clouds. The formation and persistence of contrails do not require as high ambient humidity as the formation of natural cirrus (Minnis et al. 2004). Spichtinger et al. (2003) used carefully calibrated and corrected RS80-A radiosondes to detect ice supersaturation. Unfortunately, radiosonde reports do not contain any information about the concentration of ice crystals along their path; therefore, it is not possible to distinguish between cloudy and cloud-free parts of the profile. With the ARSCL cloud product at ARM SGP central facility (CF), it is possible to detect cloud–free ice-supersaturation layers. . .

Some more science that code 3 is absolutely forbidden to read!!!!

Water vapor amounts in the upper troposphere are crucial to understanding the radiative feedback of cirrus clouds on the Earth's climate. We use a unique, year-long dataset of water vapor mixing ratio inferred from ground-based Raman lidar measurements to study the role of ice supersaturation in ice nucleation processes. We find that ice supersaturation occurs 31% of the time in over 300,000 data points. We also examine the distribution of ice supersaturation with height and find that in the uppermost portion of a cloud layer, the air is ice supersaturated 43% of the time. These measurements show that large ice supersaturation is common in cirrus clouds, which supports the theory of ice forming homogeneously. Given the continuous nature of these Raman lidar measurements, our results have important implications for studying ice nucleation processes using cloud microphysical models.

ABSTRACT
We compute upper tropospheric relative humidity profiles using water vapor profiles measured by an airborne DIAL and a ground-based Raman lidar. LASE water vapor and MTP temperature profiles acquired from the NASA DC-8 aircraft during the recent Pacific Exploratory Mission Tropics B (PEM Tropics B) field mission in the tropical Pacific and the SAGE-III Ozone Loss and Validation Experiment (SOLVE) in the Arctic as well as water vapor profiles derived from the ground-based DOE ARM Southern Great Plains (SGP) CART Raman lidar are used. Comparisons of the lidar water vapor measurements with available in situ measurements show reasonable agreement for water vapor mixing ratios above 0.05 g/kg. Relative humidity frequency distributions computed using LASE data indicate that ice supersaturation occurred about 5-11% of the time when temperatures were below –35oC. While a higher frequency of ice supersaturation was observed during SOLVE, higher peak values of relative humidity were observed during PEM Tropics B. The relative humidity fields associated with cirrus clouds are also examined.

In recent years it has become evident that the relative humidity with respect to the ice phase of water (RHi) in the upper troposphere (UT) is often above saturation, i.e. RHi > 100 %. Regions containing air masses with RHi > 100 % have been termed "ice-supersaturated regions" (ISSRs, Detwiler and Pratt, 1984; Gierens et al., 1999). As a phenomenon in the water vapor field, essential for weather and climate, and because of their importance as cirrus formation regions, ISSRs should be a topic both in the GVaP and GCSS parts of GEWEX.

The project studied the formation of soot particles and other aerosols in jet engines and in the atmosphere,
their influence on the formation of the ice phase in contrails and cirrus clouds, and their
impact on air composition, cirrus, and climate. It provided a first estimate of the contribution of
aviation to changes of the upper tropospheric aerosol and ice particle budget.

I dont want to get caught in your circle jerk, I really dont.

You know you're really bad at this...

That entire post made me laugh. Ive shown this thread to a fellow electrical engineer and he also laughed. A cpl points made me laugh the most tho:

How do you do testing without costing a civilian a lot of money?

One civilian claimed he did testing...

the aerosol spray that is used is designed to stay aloft and spreads in a way that it would be nearly impossible to take an accurate sample from what falls to the ground, it gets spread over to much area for this.

Jack McConnell et al.: Program for study of the potential
impact of aviation emissions including aerosols on the upper
troposphere lower stratosphere region using GEM-AQ

Alexander Mangold: Cirrus cloud microphysics and its
dependency on aerosol type, temperature and cooling rate

Andrew Gettelman: Impacts of Supersaturation in the UT/LS
based on global models

Claudia Stubenrauch: Persistent contrails and their
environment from TOVS Path-B

Commercial black carbon aerosol particles at sub-micron sizes displayed ice-forming ability at upper tropospheric temperatures in the CFDC even without H2SO4 uptake, apparently reflecting the operation of a deposition/sorption ice nucleation mechanism on hydrophobic soot. Multi-layer coatings of H2SO4 on particles led to onset conditions for ice formation that could only be explained by a heterogeneous freezing process. These onset conditions trend with those inferred for continental cirrus by Heymsfield and Miloshevich (1995). Other results and implications for cirrus and contrail formation are described in DeMott et al. (1999).

CCN supersaturation spectra measurements for 0.05 mm combusted jet fuel aerosol particles suggested that these particles contained around 10% soluble mass. Other experiments indicated that the soluble component was probably acidic sulfate, although condensed organic compounds may also have been present in aerosols. Unlike the studies on the coated black carbon particles, the smaller combustion particles did not show evidence of being active heterogeneous ice nuclei in cirrus conditions (see attached Figure 2). The results were most consistent with homogeneous freezing of the liquid component of the particles, assuming this was sulfuric acid. The implication for aircraft contrail formation is that exhaust particles containing insoluble cores are probably the first to catalyze ice formation, but still require RH near water saturation to do so. These results suggest a negligible effect of exhaust aerosols on cirrus clouds in aircraft corridors in comparison to background sulfates. The potentially higher ice nucleation efficiency of larger exhaust residues that result from ice contrail persistence and processing remains to be investigated.

Abstract—Automatic contrail detection is of major importance
in the study of the atmospheric effects of aviation. Due to the large
volume of satellite imagery, selecting contrail images for study by
hand is impractical and highly subject to human error. It is far
better to have a system in place that will automatically evaluate an
image to determine 1) whether it contains contrails and 2) where
the contrails are located. Preliminary studies indicate that it is
possible to automatically detect and locate contrails in Advanced
Very High Resolution Radiometer (AVHRR) imagery with a high
degree of confidence.
Once contrails have been identified and localized in a satellite
image, it is useful to segment the image into contrail versus
noncontrail pixels. The ability to partition image pixels makes it
possible to determine the optical properties of contrails, including
optical thickness and particle size. In this paper, we describe a
new technique for segmenting satellite images containing contrails.
This method has good potential for creating a contrail
climatology in an automated fashion.
The majority of contrails are detected, rejecting clutter in
the image, even cirrus streaks. Long, thin contrails are most
easily detected. However, some contrails may be missed because
they are curved, diffused over a large area, or present in short
segments. Contrails average 2–3 km in width for the cases studied.

Long-lasting contrails form in ice-supersaturated air masses. Such air masses occur far more frequently than thought some time ago. The supersaturation is not well represented in weather prediction models nor in other models.
- The impact of the overall propulsion efficiency of modern engines on contrail formation has been confirmed experimentally (see our paper in J. Aircraft, 2000).
- the line-shaped contrails cause a radiative forcing (RF) which is significantly (order factor 5) lower than estimated in the IPCC (1999) report, however the uncertainty is still large. The Ponater paper in JGR (2002) underestimated the RF because of some misrepresentation of radiative forcing of cirrus in the climate model in the infrared, as explained in the paper by Marquart and Mayer in GRL (2002).
- We find growing evidence for cirrus changes by aircraft emissions (either due to the triggering of cirrus formation by contrails or due to aerosols from air traffic). The RF from this effect can be considerably larger than what was estimated in IPCC (1999), but the uncertainty is still very large and it will be difficult to reduce the uncertainties easily.

ABSTRACT: The future development of contrails is investigated by means of a contrail parameterization developed for the ECHAM general circulation model, considering changes in air traffic, aircraft technology, and climate change. Time slice simulations show an increase in both contrail cover and radiative forcing (RF) by roughly a factor of 4 between 1992 and 2050. The simulated contrail cover for 1992 agrees well with respective observations. Some sensitivities, such as the impact of different air traffic inventories, the effect of systematic errors in the model climate, the uncertainty due to short observation periods, and the impact of the daily cycle of air traffic are discussed.

While quantification of the effects of NOx and water vapor is still at an early stage there is evidence that contrail formation could make a significant contribution to global warming. This paper builds on previous research that analyzed a policy of restricting air transport cruise altitudes to eliminate contrail formation. Our previous work [Transport. Res. D 7(6) (2002) 451], examined altitude restrictions in European airspace and concluded that this could be a beneficial policy for reducing climate change impacts from aviation. Since most of the flights in European airspace are short-haul flights, this paper evaluates the trade-offs between altitude restrictions, fuel burn and journey times for longer haul flights of up to 6000 nm. Our focus is on the North Atlantic and US airspace and we examine potential contrail fraction to determine optimal cruise altitudes for reducing contrail formation. Changes in fuel burn and travel times associated with flight levels of 18,000 and 31,000 ft for different aircraft types are analyzed. We find that, in most cases, CO2 emission increases would be unlikely to entirely counteract the benefit of possible reductions in contrail formation. For some aircraft types, the percentage increase in emitted CO2 was found to be strongly dependent on journey length. In general, journey times appear not to be a major issue except for some aircraft types. Our results suggest that reducing aircraft cruise altitudes could be a beneficial policy for mitigating climate change impacts from the aviation sector. This is clearly dependent on aircraft type and the distances traveled, but more importantly on ambient atmospheric conditions which can vary significantly between regions and due to daily variation. This suggests that real time flight planning to minimize contrail formation should be investigated as a possible climate mitigation policy.