Dandaweedman

LAMP - An electrically energized source of light, commonly called a bulb or tube.

LAMP LIFE - A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions.

LAMP LUMEN DEPRECIATION (LLD) - The decrease over time of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors.

LAMP STARTING - Generic term used to describe a discharge lamp's starting characteristics in terms of time to come to full output, flicker, etc.

LIGHT - Radiant energy which can be sensed or seen by the human eye. The term generally applied to the visible energy from a source. Light is usually measured in lumens or candlepower. When light strikes a surface, it is either absorbed, reflected or transmitted. Visible light is measured in lumens.

LIGHT MOVER - A motorized device which moves an HID lamp back and forth across the ceiling of a grow room to provide more even distribution of the light.

LUMEN - A measurement of light output; refers to the amount of light emitted by one candle that falls on one square foot of surface located at a distance of one foot from the candle.

LUMINAIRE - A complete lighting unit, consisting of a lamp or lamps together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to as a "fixture."

LUX - A standard unit of illuminance. One lux is equal to one lumen per square meter.

METAL HALIDE LAMP - A high-intensity-discharge lamp in which the light is produced by arcing electricity through a mixture of metal halides. The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and "bushiness" while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.

MERCURY VAPOR LAMPS - The oldest member of the HID family, mercury vapor lamps work by arcing electricity through mercury vapor. While more efficient than incandescent, halogen and fluorescent lamps, mercury vapor lamps have the least efficient lumen-to-watt ratio of the entire HID family. This, combined with an improper color spectrum for horticultural applications, makes mercury vapor lamps a poor choice for a grow light.

NECK - The narrow, tubular end of the HID bulb, attached to the threads.

PARABOLIC REFLECTOR - A lighting distribution control device that is designed to redirect the light from an HID lamp in a specific direction. In most applications, the parabolic device directs light down and away from the direct glare zone.

PHOTOPERIOD - The relative periods of light and dark periods within a 24-period. Also referred to as daylength.

PHOTOSYNTHESIS - The growth process by which plants build chemical compounds (carbohydrates) from light energy, water and CO2 (carbon dioxide).

PHOTOTROPISM - The gravitation of a plant part toward a light source.

REFLECTOR - The term sometimes used to refer to the reflective hood of an HID lamp.

REFLECTIVITY - The measure of the reflective quality of a surface; the relative ability of a given surface to reflect light away from it without absorbing, diffusing or otherwise compromising the light's quality, intensity and spectrum.

SOCKET - The threaded, wired receptacle that an HID bulb screws into.

SODIUM LAMP (HIGH-PRESSURE SODIUM LAMP) - High-pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

SON-AGRO - A sodium bulb which, according to the manufacturer, produces 30% more blue light than standard sodium bulbs. The 430-watt SON AGRO also emits 6% more light than the standard 400-watt sodium lamp.

SPECULAR REFLECTION - The redirection of incident light without diffusion at an angle that is equal to and in the same plane as the angle of incidence.

STERADIAN - A unit solid angle on the surface of a sphere equal to the square of the sphere's radius.

TRANSFORMER - The component in the ballast that transforms electric current from one voltage to another.

U (for UNIVERSAL) - An industry code indicating that the bulb can be operated in any position: horizontal, vertical (base up) or any other.

ULTRAVIOLET (UV) LIGHT - Light with very short wavelengths, out of the visible spectrum.

UNDERWRITERS LABORATORIES (UL) - A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized UL and other standards. A UL listing is not an indication of overall performance.

WATT (W) - A unit used to measure electric power. One watt equals one joule/second.

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