December 08, 2016
The photo at top showing an ornate condensation trail (jet contrail) over Paris, France, was captured from the window of my eighth floor flat in the City of Light. The regularly spaced lobes protruding below the base of the contrail result from the turbulent flow of the jet's wings interacting with each other. Swirling in opposite directions in the aircraft's wake, these vortices form a periodic pattern of turbulent downdrafts. Details of this flow can be seen in the bottom photo. Both photos were taken on November 17, 2016, at approximately 1:30 p.m.
Photo Details: Top - Camera Model: Canon EOS 7D; Lens: 17-70mm; Focal Length: 70mm; Aperture: ƒ/14.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 100; Software: Adobe Photoshop CC 2015 (Windows). Bottom - same except: via an Orion 80ED refractor telescope; Focal Length: 50mm; Exposure Time: 0.0020 s (1/500).
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