Rainbow over Piberbach
The photo above shows a jaunty rainbow stretching over a cornfield near Piberbach, Austria. My shadow clearly shows the direction of the antisolar point — the only direction where rainbows can be observed. Photographer: Herbert Raab; Herbert’s Web site
Note that the fainter secondary bow is also visible (at left). This bow is caused by two internal reflection of sunlight in raindrops. Since some light is lost with each additional reflection, secondary bows are only 43 percent as bright as the primary bow. Photo taken on July 21, 2011.
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