Discovery Bay Low Rainbow

July 13, 2010


Photographer: Phillip Lachman
Summary Authors
: Phillip Lachman; Jim Foster

While traveling along the Olympic Highway from Seattle to Forks, Washington we noticed an unexpected, stunning rainbow in the mist over Discovery Bay. It was mid-morning on April 4, 2010, and we had just driven through an odd shower of hail, snow and rain. Rainbows are, of course, most noticeable when they're high in the sky, but sharp-eyed observers may detect them even near the horizon. However, rainbows can only be seen when the Sun is less than 43 degrees above the horizon. On this early spring day the Sun was just barely below this altitude. Fortuitously, we were ideally positioned between the Sun and the spring shower to observe just the top of this alluring bow before it was doused by, well, the geometry of light. Discovery Bay was named by George Vancouver after the Discovery, a ship used in his 1792 expedition of the area. Not all bows require raindrops. See tomorrow's Earth Science Picture of the Day.

Photo Details: Camera: FUJIFILM FinePix S7000; Focal Length: 46.8mm; Aperture: f/7.0; Exposure Time: 0.0021 s (1/480); ISO equiv: 160.