Rainbow Over Piberbach, Austria

September 09, 2011

Rainbow_2011_07_21_Raab (3)

Photographer: Herbert Raab; Herbert's Web site
Summary Author: Herbert Raab; Jim Foster

September 2011 Earth Science Picture of the Day Viewer's Choice

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. 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.

Photo details: Canon EOS 550D camera; ISO 200; Peleng 8mm fisheye lens; f/8; aperture mode, corrected by -1 stop, resulting in 1/60 sec. exposure.