IYL 2015 Images

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    Sun Rays Over Iowa Iowa, U.S.

    This photograph captures the setting Sun over northeastern Iowa. Sun rays, also called "crepuscular rays," are rays of sunlight that sometimes appear around sunrise and sunset. These rays are caused when the sunlight streams through gaps in certain types of clouds under particular conditions. Even though the sun rays appear to be radiating from the Sun itself, this is an effect of perspective. In fact, the rays are nearly parallel, but look like they emanate from the Sun due to the same visual effect that makes train tracks or other parallel lines appear to converge in the distance.
    Image Credit: Thomas DeHoff
    view and download image here. http://lightexhibit.org/photoindex.html

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    Pink & Purple Sunset, Rhode, Island

    At sunrise and sunset, light from the Sun must take a much longer path through the Earth's atmosphere than it does during the middle part of the day. This means more of the blue and indigo light of sunlight is scattered away because these shorter wavelengths of visible light are more affected by air molecules in the atmosphere. This often allows more of the red and orange light to reach the Earth's surface. Other factors -- including dust, pollution, haze, and cloud formations – may also affect the colors of a sunset, creating a more complicated palette of light as the Sun dips below the horizon.
    Image Credit: Richard F Staples, Jr.
    view and download image here. http://lightexhibit.org/photoindex.html

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    Sunset (Lensing) Iowa, USA

    Image Credit: Thomas DeHoff
    view and download image here. http://lightexhibit.org/photoindex.html

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    Red Sunset Moorea-Maiao, Windward Islands, French Polynesia

    Why do sunsets often appear red? The answer has to do with a particular behavior of light: scattering. When sunlight strikes certain atoms and molecules in the Earth's atmosphere, some of the light is absorbed and re-emitted as a light wave in various directions. This means less of it reaches us on the surface. Due to the composition of the planet's atmosphere, the shorter wavelength colors of the rainbow are scattered more. Our Sun gives off light in all colors, but its light is most intense in yellow (which is why it appears yellow when we see it midday). Photos from above the atmosphere show a white sun, so the sun's yellow appearance is the result of scattering. At sunset, the sunlight must pass through more of the Earth's atmosphere and, thus, more of the yellow wavelength is scattered away. This leaves us frequently with a reddish orange sunset to admire.
    Image Credit: J L Spaulding, creative commons license
    view and download image here. http://lightexhibit.org/photoindex.html

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    Sunset Over China

    One of the most common—but perhaps overlooked—behaviors of light is that it bends. Or, rather, the path that light takes can be bent. You may not realize this happens all around us, including frequently as the Sun sets. The particles in the Earth's atmosphere bends the path that light takes as it travels from the near vacuum of space into the relatively thick layer that surrounds our planet. (This has to do with what scientists call "the index of refraction" which measures how fast light travels.) Because the rays of light from the Sun must travel through more of the atmosphere as it nears the horizon, the image of the Sun gets distorted. In this photo, taken by a naval officer aboard a ship on the South China Sea, the Sun appears both redder and a little more squashed that it does when it does for most of the rest of the day.
    Image Credit: U.S. Navy photo by Cmdr. Ed Thompson
    view and download image here. http://lightexhibit.org/photoindex.html