Accent Lighting: Directional light used to contrast ambient lighting to highlight a particular item or object.

Ambient Light: General lighting which evenly illuminates a given space.

Cathode:  Fluorescent lamp. A mounted coil within each end of the tube, treated with an electron emitting coating.  Electrons "jump" across the tube creating an electric arc. When the coating is used up, the lamp no longer operates.

Chroma: Color

Color Rendering Index (CRI) : A measurement which rates how accurately colors are reproduced under a given light source. <60 is considered poor, 70-79 fair, 80-89 good, 90+ excellent.  CRI can only be compared between lamps of the same color temperature. CLICK FOR ILLUSTRATION

Chromatic Shift:  Where colors appear different when taken from one light source to another.

Color Temperature: A measurement used to describe the "whiteness" of a light source, measured in degrees Kelvin.  Imagine a horse shoe steadily heated. It glows dim red at first, orange, yellow, yellow-white, white, then blue-white.  The higher the temperature, the "cooler" the light. Incandescent light is around 2700-3200K, and fluorescent light can range from 2700K upward. Summer noon sunlight is about 5600K, and diffused sunlight or northwest sky is about 7500-10,000K.  Color temperature has nothing to do with the heat of the actual lamp. CLICK FOR ILLUSTRATION

Contrasting: The art of pitting ambient and accent lighting against each other for dramatic highlights.  Using high Kelvin under low Kelvin lamps adds depth and dimension.  Accents which are 3-5 times brighter than ambient light creates texture. Combining the two techniques makes objects and items stand out.

Cool Light, Warm Light: Cool light leans to the blue side of the spectrum (4100K and up), while warm light is richer in yellow, orange, and red.  Blues appear to recede from the observer, reds advance. Thus, using warm accents over cool ambient light creates a dramatic push-pull effect.
This also is why rooms with higher (bluer) temperature lamps appear larger, while red-rich warm light makes spaces seem smaller.

Cool White: The basic bargain fluorescent introduced in 1938. Poor color rendering (64), no scotopic enhancement. Most commenly used fluorescent lamp in America. Banned in much of Europe due to poor performance.

Daylighting:  See Skylighting

Halogen Light: An improvement upon basic incandescent that has a "whiter" light (3000K +/-) light than incandescent.  The filament of an ordinary incandescent lamps slowly evaporates to the inside of the glass surface over time, but halogen's high pressure gasses allow the evaporated tungsten to fall back to the filament.

Light, Sunlight: The direct rays of the sun.

Light, Skylight: (1) Diffuse light from a lightly overcast sky. (2) Term used to describe light from the northwest sky. (3) Translucent ceiling window that passes outdoor light to the indoors. All three have a similar color temperature of 7000-8000K.

Light, Daylight: (1) Usually describes the combination of sunlight and sky light with a color temperature of approx 5000-5600K at summer noon.  (2) Color designation of a fluorescent lamp with a color temperature of 6500K.

Loaded Spectrum/ Equalized Spectrum: The new technology offering a dramatic improvement over full spectrum lamps.  Loaded spectrum lamps are "loaded" with an innovative scotopic : photopic peak ratio plus a strong red content for maximum acuity and color rendering.

Moth Effect: Describes the phenomina of shoppers gravitating to brightly lit stores.

Phosphor: The powder which coats the inside of fluorescent lamps. The phosphor converts ultra-violet  to visible light.  The type of phosphor dictates the lamp color.

Photopic:   The light to which our  "day" (cone) vision is most sensitive. Peaks in the green-yellow portion of the spectrum.

Scotopic: The light to which our  "night" (rod) vision is most sensitive. Peaks in the cyan portion of the spectrum.

Spectral Energy Distribution (SED, SPD): A graphic representation showing relative output of various colors in a given light source.

Skylighting: Lighting a store/business with outside light by passing through translucent ceiling panels.  See section on skylighting.