Sunset Sequence from Port Orford, Oregon
August 13, 2010
The photo sequence above, showing the Sun plunging into the Pacific, was taken from a dock in Port Orford, Oregon in early July 2010. I've never seen the Sun get so distorted and change shapes so quickly. Layers seemed to separate from the top of the Sun and then simply vanish. It was mesmerizing to watch. A clue as to what’s occurring here is the increased distortion of the solar disk as it sinks closer to the horizon. This distortion results from atmospheric refraction (variations of the index of refraction with height) and is particularly evident when the path length of sunlight is at its maximum – as the Sun is setting or rising. In essence, light from the bottom of the Sun passes through more air (longer path length) than the light coming from the upper portion of the Sun. The bottom of the solar disk is therefore refracted upwards more noticeably than the top, causing the Sun to look flattened. Uncommon temperature gradients and temperature inversions can act to refract light in unexpected ways. Not long before sunset, the temperature dropped rapidly, from just over 80 F (27 C) to approximately 56 F (13 C). Note that the Sun is seen setting adjacent to a sea stack.