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6 answers

That's just how your eyes perceive it. It is, in fact, a smooth transition.

2007-07-02 08:16:10 · answer #1 · answered by Anonymous · 1 0

The colors of the rainbow, considering only the optical phenomenon of difraction, merge seamlessly throughout the spectrum, but human cultures has tried to distinguish discrete colors. At least in the Western societies, seven colors are classically recognized:

red,
orange,
yellow,
green,
blue,
indigo and
violet.
The number seven was picked because of its popularity in arcana, which ultimately come from the seven astrological “planets” (five planets visible to unaid eye plus Sun and Moon).

2007-07-02 08:16:34 · answer #2 · answered by DanE 7 · 0 0

What makes the colors in the rainbow?
The traditional description of the rainbow is that it is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see.

The colors of the rainbow arise from two basic facts:

* Sunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666.
* Light of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example).

Descartes and Willebrord Snell had determined how a ray of light is bent, or refracted, as it traverses regions of different densities, such as air and water. When the light paths through a raindrop are traced for red and blue light, one finds that the angle of deviation is different for the two colors because blue light is bent or refracted more than is the red light. This implies that when we see a rainbow and its band of colors we are looking at light refracted and reflected from different raindrops, some viewed at an angle of 42 degrees; some, at an angle of 40 degrees, and some in between. This is illustrated in this drawing, adapted from Johnson's Physical Meteorology. This rainbow of two colors would have a width of almost 2 degrees (about four times larger than the angular size as the full moon). Note that even though blue light is refracted more than red light in a single drop, we see the blue light on the inner part of the arc because we are looking along a different line of sight that has a smaller angle (40 degrees) for the blue.

Ana excellent laboratory exercise on the mathematics of rainbows is here, and F. K. Hwang has produced a fine Java Applet illustrating this refraction, and Nigel Greenwood has written a program that operates in MS Excel that illustrates the way the angles change as a function of the sun's angle.

2007-07-02 08:16:01 · answer #3 · answered by Anonymous · 0 0

Our human eyes have evolved to detect only 3 colours:
Red for the earth, Green for grass & trees, Blue for sky.
Other creatures, like dogs, can only tell blue & yellow.
We have come to label these distinct colours:
Red, Orange, Yellow, Green, Blue, Purple.
But in reality the shades of colour are continuous.

2007-07-02 08:23:16 · answer #4 · answered by Robert S 7 · 0 0

The wavelengths of color from the rainbow do indeed gradate smoothly from red to violet. However, our perception of color is not so smoothly gradated. We can only directly sense the three "primary" colors (which are primary only because they are the colors we directly sense), and all others are combinations of those.

2007-07-02 08:23:57 · answer #5 · answered by ZikZak 6 · 0 0

There are clear differences in the frequencies of each of these colours, hence the different layers of the spectrum.

2007-07-05 11:07:54 · answer #6 · answered by johnandeileen2000 7 · 0 0

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