The architecture of light: architectural lighting design concepts and techniques. A textbook of procedures and practices for the architect, interior designer and lighting designer pdfdrive com

Figure 5.1 Radiation, including light, is best imagined as squiggly lines vibrating at different rates as they travel through space.
We don’t need to visualize these units. We need only to know that in scientific circles, wavelength, often expressed in Nanometers, is a perfectly appropriate way to describe radiation, including visible light. Figure 5.2 shows the entire known spectrum of radiation and the corresponding range of wavelengths for the different types. You can see that “light” is a family of radiation at the “short” end of the spectrum, that is to say radiation which has shorter wavelengths and vibrates relatively fast.
Figure 5.2 The complete spectrum of electro-magnetic radiation including the portion we call visible light.
Generally, we say that human color vision can detect radiation with wavelengths as short as 380 Nanometers and wavelengths as long as 770 Nanometers. So it is within this range that we have the “visible spectrum” or radiation we call “light.” Anything vibrating faster, or vibrating slower, we no longer “see.” The radiation is still there; we simply can no longer detect it with our eyes.
Humans do have mechanisms for detecting other types of radiation, but
certainly not with the acuity of the “visible spectrum.” Infra-red radiation, which lies just beyond the visible spectrum, is a good example. Humans don’t detect it with their eyes, but they do detect it with their nerves as various levels of radiant
heat. We are commonly told that heat rises, but, more accurately, heated air rises. Heat, itself, can be directed with reflectors just like other forms of radiation.
Figure 5.3 An articulation of the wavelengths of radiation that constitute the visible spectrum.
Most humans have an amazing ability to distinguish between different types and combinations of visible light. The articulation of our visual system is evident in the plethora of names that we have given to all of these light experiences. We name them as colors, and there is no shortage of subtle variation in our color experiences. It is important, however, to remind ourselves that “color” is simply a name for an experience. Light itself has no color. It is only
when different wavelengths of radiation reflect off of surfaces in our environment and enter our eye that we have an experience that we can name as a “color.” Hence every wavelength of radiation in the visible spectrum will cause a fairly predictable color experience. And so, rather than argue about whether an object is perceived as yellowish-orange or “canary yellow”, we could simply describe the radiation by its wavelength in Nanometers to end the debate. It is also worth noting that the acuity of color vision varies from person to person depending on his / her physiological make-up. Various forms of color deficiency can drastically reduce the number of unique color experiences of which a person is capable. Studies show that about eight percent of males and less than one percent of females suffer some form of color deficiency.