Professional Pilot, March 2016
WX BRIEF Contrails Lets observe understand and learn from those white ribbons that paint out behind high flying aircraft Contrails as shown in the aerial photograph L and satellite image of the US Southeast R are a ubiquitous presence across many flight corridors Scientists note that interception of infrared radiation by contrails is a contributing factor in atmospheric warming an effect that may be enhanced as demand for aviation increases T he box formations of 8th Air Force Boeing B17s were arrayed across the midday sky as they crossed the Dutch coastline at 25000 ft MSL Sadly for them it was a crisp and clear winters day which meant no low clouds to mask them from the German 88s pointing up at them from below Making matters worse was the fact that almost immediately after crossing the coast the entire formation had begun producing their own trailing cloud ribbons with each aircraft leading at the tip of a long contrail German gunners quickly zeroed in on the formation and began to deliver a deadly barrage of antiaircraft fire Squadron leaders ordered the aircraft to stagger altitudes in hopes not only of making it more difficult for the antiaircraft guns to set their fuses to explode at the right height but also to see if other altitudes might be dry enough to dissipate the tell tale contrails produced by their aircraft Fortunately the tail gunner of one aircraft that had descended to 20000 ft noted that their contrail 90 PROFESSIONAL PILOT March 2016 had disappeared And as other aircraft followed suit the effectiveness of the defensive guns was reduced Contrails have been a part of aviation since the early high altitude flights took to the skies during the First World War While it could easily have been miscon By Karsten Shein Comm Inst Climate Scientist Flight of Boeing B17 Bombers produce contrails over Italy in 1943 The high altitudes often used by these aircraft to avoid antiaircraft fire resulted in widespread contrails that allowed enemy gunners and pilots to more easily target the aircraft Photo courtesy USAAC Photo courtesy NASA strued as some sort of engine problem these pioneer pilots and even those observing from the ground seemed to understand that these smoky tracks in the sky behind their aircraft were in fact due to the condensation of the engine exhaust into a ribbon of cloud
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