Spectral, Irradiance, and Temporal Aspects of Natural and Artificial Light

Light is defined by some as radiant energy that is capable of exciting the retina and producing a visual sensation.' For humans this effectively defines the spectral range of light as that of the rainbow, that is, wavelengths of about 360 to 830 nanometers (nm).* The visual sensation produced by the rainbow is one of both color (hue) and brightness, but the legal and technical standards by which light is bought and sold effectively recognize only the brightness related s t imul~s .~" The standards do not recognize ultraviolet (UV) radiation, which extends to wavelengths of about 290 nm in the natural light environment. Nor is there any specification for time in relation to light, the transition between on and off phases of light, or the periodicity of light exposure. The fact that radiation of all wavelengths from 290 nm to 830 nm, as well as its time variations, can have medical or biological effects suggests the need for a review of the differences between natural light and artificial light under which most people in industralized countries are working today. Accordingly, in this paper basic data are presented, and/or referenced, for natural and artificial light of wavelength 290-830 nm from which other related radiometric, photometric, colorimetric, chronometric, and biometric data of interest can be derived. Examples of these are given and discussed in the context of existing standards and laws defining light and limiting energy consumption for generating it.

[1]  B L Diffey,et al.  The calculation of the spectral distribution of natural ultraviolet radiation under clear day conditions. , 1977, Physics in medicine and biology.

[2]  D. C. Morgan,et al.  Photoperiodic time signals during twilight , 1984 .

[3]  R. Wurtman,et al.  Stimulation by Artificial Lighting of Calcium Absorption in Elderly Human Subjects , 1971, Nature.

[4]  John Calkins,et al.  The Role of Solar Ultraviolet Radiation in Marine Ecosystems , 1982 .

[5]  R. Anderson,et al.  Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin. , 1982, Science.

[6]  W. Mendelson,et al.  Antidepressant effects of light in seasonal affective disorder. , 1985, The American journal of psychiatry.

[7]  G. V. Rozenberg,et al.  Twilight: A Study in Atmospheric Optics , 1966 .

[8]  M. J. Newman,et al.  Efficiency of Convection and Time Variation of the Solar Constant , 1978, Science.

[9]  A. Green,et al.  Ultraviolet limit of solar radiation at the earth's surface with a photon counting monochromator. , 1978, Applied optics.

[10]  M. Thekaekara,et al.  Solar radiation measurement: Techniques and instrumentation , 1976 .

[11]  B. Goldberg Radiometric Measurements in the UV-B Region of Daylight , 1982 .

[12]  H. Xu Color-rendering capacity of illumination. , 2010, Journal of the Optical Society of America.

[13]  James B. Maas,et al.  Effects of spectral differences in illumination on fatigue. , 1974 .

[14]  P. Himmelfarb,et al.  Bactericidal activity of a broad-spectrum illumination source. , 1970, Applied microbiology.

[15]  Luke Thorington,et al.  Visual and Biologic Aspects of an Artificial Sunlight Illuminant , 1971 .

[16]  Gunther Wyszecki,et al.  Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd Edition , 2000 .

[17]  K. Baker,et al.  Middle Ultraviolet Irradiance at the Ocean Surface: Measurements and Models , 1982 .

[18]  Frederick Urbach,et al.  A CLIMATOLOGY OF SUNBURNING ULTRAVIOLET RADIATION , 1982, Photochemistry and photobiology.

[19]  R L Hulstrom,et al.  Solar spectral measurements in the terrestrial environment. , 1982, Applied optics.

[20]  D A Newsome,et al.  Light suppresses melatonin secretion in humans. , 1980, Science.

[21]  J. A. Gatlin,et al.  Data on total and spectral solar irradiance. , 1983, Applied optics.