757 Dragging a Contrail

[jungle]

Taken from FL390, aircraft passing below at FL380

[Colombia]

Thats a cool shot.

[kaitanium]

sweeeet

[olly_k]

Taken from FL390, aircraft passing below at FL380

wow, are contrails always that dirty looking from up their?

[jungle]

wow, are contrails always that dirty looking from up their?

Good question. Contrails are mostly made from water vapor in the surrounding air, the small amount of particulates in the jet exhaust trigger freezing of the supercooled vapor. The burnt fuel also produces water vapor and at -50 degrees C or so it freezes within a very short period.

This one appears grey because of the lighting, much as a white cloud may appear grey in different light. Viewed against the sky this would have looked white.




From Wiki:

Condensation from engine exhaust

Airplane trails.A vehicle engine's exhaust increases the amount of moisture in the air, which can push the water content of the air past saturation point. This causes condensation to occur, and the contrail to form. When the fuel is burned, the carbon combines with oxygen to form carbon dioxide; the hydrogen also combines with oxygen to form water, which emerges as in the exhaust. For every gallon of fuel burned, approximately one gallon of water is produced, in addition to the water already present as humidity in the air used to burn the fuel. At high altitudes this water vapour emerges into a cold environment, (as altitude increases, the atmospheric temperature drops) and the local increase in water vapour density condenses into tiny water droplets and/or desublimates into ice. These millions of tiny water droplets and/or ice crystals form the contrails. The energy drop (and therefore, time and distance) the vapour needs to condense accounts for the contrail forming some way behind the aircraft's engines.The majority of the cloud content comes from water trapped in the surrounding air. At high altitudes, supercooled water vapour requires a trigger to encourage desublimation. The exhaust particles in the aircraft's exhaust act as this trigger, causing the trapped vapor to rapidly turn to ice crystals. Contrails will only occur when the outside air temperature around the aircraft is at or below -57 degrees Celsius.

You want deeper?

A Case Study of the Development of Contrail Clusters over the Great Lakes
David P. Dudaa, Patrick Minnisb, Louis Nguyenb, and Rabindra Palikondac

a. Hampton University, Hampton, Virginia
b. Atmospheric Sciences, NASA Langley Research Center, Hampton, Virginia
c. AS&M, Inc., Hampton, Virginia

ABSTRACT
Widespread persistent contrails over the western Great Lakes during 9 October 2000 were examined using commercial flight data, coincident meteorological data, and satellite remote sensing data from several platforms. The data were analyzed to determine the atmospheric conditions under which the contrails formed and to measure several physical properties of the contrails, including areal coverage, spreading rates, fall speeds, and optical properties. Most of the contrails were located between 10.6 and 11.8 km in atmospheric conditions consistent with a modified form of the Appleman contrail formation theory. However, the Rapid Update Cycle-2 analyses have a dry bias in the upper-tropospheric relative humidity with respect to ice (RHI), as indicated by persistent contrail generation during the outbreak where RHI 85%. The model analyses show that synoptic-scale vertical velocities affect the formation of persistent contrails. Areal coverage by linear contrails peaked at 30000 km2, but the maximum contrail-generated cirrus coverage was over twice as large. Contrail spreading rates averaged around 2.7 km h−1, and the contrails were visible in the 4-km Geostationary Operational Environmental Satellite (GOES) imagery approximately 1 h after formation. Contrail fall speed estimates were between 0.00 and 0.045 m s−1 based on observed contrail advection rates. Optical depth measurements ranged from 0.1 to 0.6, with consistent differences between remote sensing methods. Contrail formation density was roughly correlated with air traffic density after the effects of competing cloud coverage, humidity, and vertical velocity were considered. Improved tropospheric humidity measurements are needed for realistic simulations of contrail and cirrus development.

Current theory:

http://ams.allenpress.com/perlserv/?...E2.0.CO%3B2#S3

[RCoulter]

I like it :)

[Eagle]

wow, are contrails always that dirty looking from up their?
Makes it look like she's burning oil.

It is a cool shot.

[olly_k]

http://ams.allenpress.com/perlserv/?...E2.0.CO%3B2#S3

Hi Jungle thanks for that! I got up to the bit where you said "you want deeper" :D