Home Up sun.paths.3ex changes.sun.angle analemma table.of.length.daylight sunangle.length.day.solstices.equi changes.temp.change.latitude mechanisms.heat.transfer blue.skies.ex atm.windows greenhouse.effect clouds

 

Short wavelengths (blue and violet) of visible light are scattered more effectively than are longer wavelengths (red, orange). Therefore, when the Sun is overhead, an observer can look in any direction and see predominantly blue light that was selectively scattered by the gases in the atmosphere. By contrast, at sunset, the path that light must take through the atmosphere is much longer. Consequently, most of the blue light is scattered before it reaches an observer. Thus, the Sun appears reddish in color.