Green Flash Turning Blue

April 15, 2014

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Photographer: Laurent Laveder; Laurent’s Web site
Summary Authors: Laurent Laveder; Jim Foster

This photo sequence shows a green flash (second and third photos) and blue flash (fourth and fifth photos) observed at sunset near the Mont Saint-Michel, France. The weather had been fair for several days as northwestern France was under the influence of a large anticyclone. When I noticed a mock mirage atop the Sun, I realized that the green flash might follow and was thus prepared to photograph it. If sunlight is refracted through a strong thermal gradient above the surface, a mock mirage may form. However, only when there's a marked vertical magnification of the mock image of the Sun (or in some cases multiple images) will color separation produced by differential refraction be visible to the eye or camera — green and sometimes blue colors. The five photos of this sequence were snapped in about 3 seconds. Always protect your eyes when looking toward the Sun, even when the Sun is low in the sky. Sequence taken on March 15, 2014.

Photo details: Camera Model: Canon EOS 6D; Lens: 100-300mm; Focal Length: 300mm; Aperture: f/8.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 800; Software: Adobe Photoshop Lightroom 5.3 (Windows).