Rainbow at Daybreak

January 01, 2013

Dawn rainbow over puget sound - mukilteo

Photographer: Rachel Petrinovich
Summary Authors: Rachel Petrinovich; Jim Foster

The photo above shows an eye-catching rainbow over Puget Sound seen from Mukilteo, Washington. Two clues evident on this picture should tell you that this bow was either snapped very early in the morning or very late in the day. One clue is visible and one is not. The first is that the primary bow arches nearly straight up. The higher in the sky a rainbow is projected, the closer to dawn or dusk it is -- this bow occurred just at daybreak. What we can't clearly see is the second clue -- the violet and blue colors are missing. When the Sun lies close to the horizon, the violets and blues are the first to be extinguished. This is because the greater path length of sunlight at sunrise and sunset effectively scatters out the shorter wavelength colors. Photo taken on September 28, 2012.