Circular Rainbow Over Düsseldorf, Germany

November 03, 2017

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Photographer: Hans Juergen Heyen 
Summary Authors: Hans Juergen Heyen; Jim Foster

Shown above is a portion of a circular rainbow as observed from the observation deck of a 580 ft (170 m) television transmission tower in Düsseldorf. In reality, all rainbows we see are portions of a circle having a radius of approximately 42 degrees. The horizon effectively blocks our view of the missing part of the circle. However, if the horizon is well below eye level, as it is when looking from a mountaintop, the roof of a high-rise building or from an airplane, a circular rainbow can be detected.

At lower left, part of the secondary bow and Alexander's dark band can be seen above the Rhine River. Note that the bridge is known as the knee bridge since the river here resembles the shape of a knee. The tower's elongated shadow is visible stretching toward the center of the circular bow -- the antisolar point. Photo taken on October 6, 2017.

Photo Details: Camera Model: Canon EOS 600D; Lens: EF-S10-22mm f/3.5-4.5 USM; Focal Length: 10mm; Aperture: ƒ/5.0; Exposure Time: 0.017 s (1/60); ISO equiv: 100; Software: Microsoft Windows Photo Gallery 6.0.6001.18000.