Spectral colors describe the color impression of the human color perception that light of a certain wavelength produces. They are created when white light is refracted through a prism. This causes the light to split into the seven spectral colors visible to the human eye, i.e. into monochromatic light of a specific wavelength that cannot be further subdivided. If these spectral colors are combined again, white light is produced once more.
In nature, this phenomenon is best observed using the example of a rainbow. Sunlight is refracted by raindrops as if through a prism, causing the spectral colors to appear in the form of a rainbow in the sky.
The spectrum of light visible to humans lies between the long-wave end of ultraviolet light (360 to 380 nm) and the short-wave beginning of infrared light (780 to 820 nm). The perceived hue changes smoothly from violet to blue to green to yellow to red.
The seven spectral colors are violet, blue, green, yellow, orange, red and indigo. They can be assigned to the following wave ranges:
- Violet: 380 to 430 nm
- Blue: 430 to 490 nm
- Green: 490 to 570 nm
- Yellow: 570 to 600 nm
- Orange: 600 to 640 nm
- Red: 640 to 780 nm
The color indigo is located in a middle range between the blue and the green wavelength range.