Natural Light

Natural light, perceived by the human eye as white light, is the result of a mixing of all the wavelengths in the visual spectrum. When such light is passed through a prism it is separated into its constituent parts and we see the familiar rainbow pattern shown alongside.

The shortest wavelengths in the spectrum appear as shades of violet/blue while the longest ones appear as shades of red. Broadly speaking the light appears to consist of three bands of color - blue, green and red. The near infinite range of hue and color visible to the human eye is a trick of perception when two or wavelengths from the visual spectrum are combined. For instance shades of yellow are generally the result of combining variable amounts of green and red.

Missing in the image above are shades of magenta/pink. Why? Because they are the result of combining blue and red - colors at the two ends of the visual spectrum. For this reason it is is often more useful to represent the visual spectrum as a color wheel, as shown in the figure, rather than as a band or an arc.