Curved Contrail, Straight Shadow

June 02, 2013

Curvedcontrailand shadow

Photographer: Francesco de Comite
Summary Authors: Francesco de Comite; Jim Foster

The photo above shows a curved jet contrail and its peculiar straight shadow made by a military jet over Mouscron, Belgium. Contrail shadows often seem counterintuitive; for one reason because we're viewing them from the perspective of looking toward the source of illumination (Sun) rather than away from it, as we usually view shadows. When this contrail passed in front of the Sun, it cast a tangential shadow on the thin cirrus cloud deck beneath it. A contrail always produces a shadow, but from the perspective of a viewer on the ground it's only visible if it's aimed at the Sun. Note that if the clouds were somewhat thicker, neither the shadow nor the contrail could have been observed. Always use extreme caution when looking in the direction of the Sun. Photo taken on April 17, 2013.

Photo details: Camera Model: Canon PowerShot S3 IS; Focal Length: 6mm; Aperture: f/7.1; Exposure Time: 0.0006 s (1/1600).