Noon sunlight

Clearly, standardized light sources are desirable for color matching, particularly in view of the phenomenon of illuminant metamerism described below. Over the years CIE has defined several standard illuminants, some of which can be closely approximated by practical sources. In 1931 there was Source A, defined as a tungsten filament incandescent lamp at a color temperature of 2854 K. Sources B and C used filtering of A to simulate noon sunlight and north sky daylight, respectively. Subsequently a series of D illuminants was estabUshed to better represent natural daylight. Of these the most important is Illuminant E). ... 

Let us now consider a shallow water body that is exposed to noon sunlight. If we keep everything in the system constant, we will reach a steady state in which... 

Calculated from L,a,b values on a Hunter color difference meter (average of six readings on each sample) exposure in Weatherometer is listed in kilojoules per square meter (ambient dry bulb temperature, 85°F 3° wet bulb temperature, 70°F 4°, black panel temperature 100°F % relative humidity, 50 8%). Each 110 kJ/m2 corresponds to about 20 h exposure to noon sunlight conditions. 

Cellulose acetate films of 8-mil thickness containing 0.5-1.0% hydroxybenzotriazole or hydroxybenzophenone UV stabilizers were the most effective in protecting Blue Wool L-4 fabrics from undergoing color changes when exposed to a xenon-arc light source that simulated 20-100 h of noon sunlight indoors under warm, moderately humid conditions. 

K f/. Average Day Light, Central Latitudes Noon Sunlight Xenon Flash Blue Blub Flash Cube... 

B. Numerical Examples for Lake Greifensee, June Noon Sunlight (1 kW m 2)... 

Figure 8.2. Ultraviolet absorption spectra of 0.05-mm polymer films and spectral irra-diance of July noon sunlight (direct beam) at 41°N latitude AP = aromatic polyester PAR = polyarylate PC = polycarbonate PE = polyethylene PET = poly(ethylene tere-phthalate) PS = polystyrene PSF = polysulfone PVC = poly(vinyl chloride). (Reprinted with permission of Technomic Publishing Co. [4].)...

Illuminant B (CIE) n. An approximation of mean noon sunlight, approximately neutral in hue, with a correlated color temperature of 4874 K. It is defined in the wavelength range of 380-770nm. 

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