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Contrails formed by aircraft can evolve into cirrus clouds indistinguishable from those formed naturally. These 'spreading contrails' may be causing more climate warming today than all the carbon dioxide emitted by aircraft since the start of aviationFull paper at





Mozaic is a project aimed at understanding the distribution of atmospheric pollutants mainly due to aircraft.   Yet the fact that Mozaic data is acquired very neatly in 3/4D increments using AMDAR and

AVOSS could unwittingly be seeding quantized artificial cloud. Flight level increments are typically 0.5 km ... for obtaining a true global ISSR distribution by joining MOZAIC data with various satellite data ... calculation is repeated for different flight levels at increments of 0.5 km ...


In order to avoid wake turbulence and clear air turbulence AMDAR/AVOSS style separations are now the norm in aviation.


2. Muons surge at Earth's surface during a solar flareThe upper atmosphere is rather like a Wilson Cloud Chamber- The author has established a link between certain types of Solar Flare and a prevalence of Persistent Spreading Contrail. 

Satellite- and spacecraft-mounted sensors observed a sudden surge in cosmic radiation near Earth on 20 January 2005, caused by a solar flare. At the same time, D'Andrea and Poirier detected a sudden ground-level increase in muons, elementary charged particles similar to electrons but heavier and not found in normal atoms. They observed the muons using Project GRAND, an array of 64 stations of proportional wire detectors in Notre Dame, Indiana. The muons were observed as they passed near the wires and were distinguished from other particles by passing undeflected through a steel plate. The surge of muons peaked between 6:51 and 6:57 Universal Time and coincided with a rise in neutrons reaching detection facilities in New Jersey and Finland. The authors hope to combine their data with that from other muon and neutron detectors around the world to learn more about the particles emitted by the Sun during solar flares.

Title: Ground level muons coincident with the 20 January 2005 solar flare

Authors: C. D'Andrea, J. Poirier, University of Notre Dame, Notre Dame, Indiana, USA.

Source: Geophysical Research Letters (GL) paper 10.1029/2005GL023336, 2005



Frédérique Auriol and Jean – François Gayet

LaMP / UPRESA CNRS 6016, Université Blaise Pascal

Clermont-Fd, France


Original measurements were obtained in contrails and cirrus clouds by using a new optical airborne probe, the ‘Polar Nephelometer’, which is the first airborne instrument to make direct in situ measurements of the scattering phase function of cloud particles over a broad range of sizes (from a few micrometers to about 500 m m diameter). These measurements were obtained during the European AEROCONTRAIL experiment held near Munich (September-October 1996) during which the probe was mounted on the DLR Falcon aircraft with PMS PCASP, FSSP-100-ER, 2D-C probes, Hallet’impactor and CVI probe. In young contrails, the measured scattering phase function is close to the theoretical results calculated from the FSSP data assuming ice spheres except in the side scattering angles. In older contrails the differences with theory are much pronounced whereas in natural cirrus the measured scattering phase function indicates major differences with those used in cloud models which assume ice spheres or simple geometric shape of ice particles. These differences are discussed in terms of interstitial aerosols and/or the presence of black carbon condensation/ice nuclei inside the condensed ice particles sampled in contrails and in terms of the shape of ice particles which appears to be irregular particularly in old contrail and in natural cirrus.

 These results highlight new potential insights on both modeling of climate processes and methodologies for cloud remote sensing from satellite measurements. – The next logical step after modeling is control of climate and weather – this is the present author’s comment


Differences in early contrail evolution of 2-engined versus 4-engined aircraft. Lidar measurements and numerical simulations _ So folks now you know why CONTRAILS DON’T LOOK LIKE THEY USED!  


Klaus Gierens, Ulrich Schumann

Deutsches Zentrum für Luft und Raumfahrt, DLR, Weßling, Germany

Ralf Sussmann

Fraunhofer-Institut für Atmosphärische Umweltforschung, IFU,

Garmisch-Partenkirchen, Germany

Jet- and vortex-regime evolution of contrails behind cruising aircraft is investigated by focusing on the role of aircraft type. Cross-section measurements by ground-based lidar and observational analysis are combined with numerical simulations of fluid dynamics and microphysics in the wake of two-engined aircraft. Depending on ambient humidity levels, contrail evolution behind short/medium-range twin-turbofan airliners is classified into two scenarios, which is in contrast to the three scenarios observed for wide-body four-turbofan aircraft (Sussmann and Gierens, 1999). In case of ice-subsaturated ambient air, a short visible contrail is formed behind two-engined aircraft that disappears before the ice is fully entrained into the wingtip vortices (in most cases » 4 s behind aircraft). The early evaporation of the ice is mainly due to the fast initial jet expansion, mixing the exhaust with the ambient air. Contrails behind wide-body four-engined aircraft always survive at least till vortex breakdown (i.e., typically 2 min behind aircraft). This is simply due to the larger ice mass in the contrail because of the higher fuel flow rate. Generally, in case of ice-supersaturation, a diffuse secondary wake evolves above the primary vortex wake. For two-engined aircraft, always the whole contrail persists, while for four-engined aircraft the primary wake disappears in most cases after vortex breakdown.


Sussmann, R., and K. Gierens, Lidar and numerical studies on the different evolution of vortex pair and secondary wake in young contrails, J. Geophys. Res., 104, 2131-2142, 1999.

American Geophysical Union

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Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 2664465 bytes)


Lidar and numerical studies on the different evolution of vortex pair and secondary wake in young contrails

Ralf Sussmann

Fraunhofer-Institut für Atmosphärische Umweltforschung, IFU, Garmisch-Partenkirchen, Germany

Klaus M. Gierens

Deutsches Zentrum für Luft und Raumfahrt, DLR, Wessling, Germany



Vortex-regime evolution of contrails is investigated by focusing on the role of ambient humidity. Lidar cross-section measurements and observational analysis are combined with numerical simulations of fluid dynamics and microphysics. Contrail evolution behind four-turbofan aircraft is classified into three different scenarios. In the case of ice-subsaturated air, a visible pair of wingtip vortices is formed that disappears at the end of the vortex regime. In case of ice supersaturation, a diffuse secondary wake evolves above the wingtip vortices. It is due to detrainment of ice particles growing by sublimation of ambient humidity. A vertical wake-gap opens between the wingtip vortices and the secondary wake. It is due to subsaturated air moving upward along the outer edges of the sinking vortex tubes accumulating around the upper stagnation point of the vortex system. The vertical wake-gap preferably occurs in the wake of heavy (four turbofans) aircraft, since the vortices behind light aircraft migrate down too slowly. The secondary wake is composed of nonspherical particles larger than the ones in the wingtip vortices which are spherical particles and/or particles smaller than ≈0.5 μm. In most cases the secondary wake is the only part of a contrail that persists after vortex breakdown. This is because the ice in the vortex tubes evaporates due to adiabatic heating as the vortices travel downward. Only in the rare case of higher ambient ice supersaturation (> 2%) do both parts of a contrail contribute to the persistent ice cloud. The number of ice crystals initially formed is typically reduced by a factor of 200 by evaporation (60% ambient humidity). This leads to a high population of interstitial particles. The results imply that formation of persistent contrails can be minimized by technical means. © 1999 American Geophysical Union

Index Terms: 0300 Atmospheric Composition and Structure; 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801).