Razor's Edge, Best of Cross Country Trip 1280x1024

As sunrise and sunset are calculated from the leading and trailing edges of the sun, and not the centre, the duration of "day" is slightly longer than "night". Further, because the light from the sun is bent by the atmospheric refraction, the sun is still visible after it is geometrically below the horizon. The sun also appears larger on the horizon, which is another optical illusion, similar to the moon illusion.

The sunset is often more brightly colored than the sunrise, with the shades of red and orange being more vibrant. The atmosphere responds in a number of ways to exposure to the sun. In particular, there tends to be more dust in the lower atmosphere at the end of the day than at the beginning. During the day, the sun heats the surface of the Earth, lowering the relative humidity and increasing wind speed and turbulence, which serves to lift dust into the air. However, differences between sunrise and sunset may in some cases depend more on the particular geographical features of the location from which they are viewed. For example, on a west-facing coastline, sunset occurs over water while sunrise occurs over land.

 
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