INTENSITY - A term referring to the magnitude of light energy per unit; light intensity diminishes evenly as you get further from the source.
KELVIN TEMPERATURE (K) - The unit of measurement to express the colour (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source. A standard clear metal halide HID lamp has an average Kelvin temperature rating of 4,000K.
KILOWATT (kW) - A unit of electric power usage equal to 1,000 watts.
KILOWATT HOUR (kWh) - A measurement of electric energy. A kilowatt hour is equal to 1,000 watts of power used over a period of one hour.
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 DEPRECIATION (LD) - The decrease over time of lamp 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 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 and reduce hotspots.
LUMEN - A measurement of light output; relative to human perception
which 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.
LUMINA IRE - 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."
(MH) 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.
(MV) MERCURY VAPOUR LAMPS - The oldest member of the HID family, mercury vapour lamps work by arcing electricity through mercury vapour. While more efficient than incandescent, halogen and fluorescent lamps, mercury vapour lamps are the least effective of the entire HID family. This, combined with an improper colour spectrum for horticultural applications, makes mercury vapour lamps a poor choice for a grow light.
MOG - Mogul base.
MOL - Maximum overall length of a lamp, from the tip of the base to the top of the bulb.
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 day length.
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.
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.
SPECULA 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. The secular inserts included in Hydrofarm’s HID lighting systems work on this principle.
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.
WATT(W) - A unit used to measure electric power. One watt equals one joule/second.
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