Sonoma Valley Rainbow
April 02, 2013
Photographer: Christine Churchill
Summary Authors: Christine Churchill; Jim Foster
Shown above is an enchanting rainbow captured above Sonoma Valley, California, in October 2012. Unlike the rainbow photo featured as the picture of the day on March 11, the shorter wavelength colors (violets and blues) of this bow are especially pronounced. The photo was taken in the early afternoon when the Sun was still relatively high in the sky, so the rainbow is more low slung than if it were taken later in the day. The higher Sun position means that the path length of sunlight is minimized and as a result, the blue colors haven't yet been scattered from our view. Note the secondary rainbow near the top of the frame. Also noteworthy are the skinny and fainter bows beneath the primary bow – supernumerary bows. When these bows are obvious, it’s a sure sign that the raindrops are relatively large. Supernumerary rainbows result from diffraction, not refraction. Bald Mountain (2,729 ft or 832 m) in the background at left is the second highest peak in the Malyacamas Mountain Range.