PuffinTuff420
Member
Light intensity is the magnitude of light energy per unit of area. It is greatest near the bulb and diminishes rapidly as it moves away from the source.for example plants two feet away from a lamp recieve one-fourth the amount of light recieved by plant one foot away from light source, an hid that imits 100,000 lumens produces a paltry 25,000 lumens two feet away. a 1000 watt hid that emits 100,000 initial lumens yeilds 11,111 lumens 3 feet away. The close marijuana is to a light source, the more PAR watts it recieves and the better it grows, as long as its not too close that heat from the lamp causes burned foliage.the relationship and the light emitted from a point source (bulb) and distance are defined by the inverse square law. This law affirms the intensity of light changes in inverse proportion to the square of distance I=l/d2 Intensity=light output/distance2. 1 lumen is equal to the amount of light emitted by one candle that falls on one square foot of surface one foot away. Lumens emmitted are only one part of the equation. lumens recieved by the plant are much more important. Lumens recieved are measured watts-per-square-foot also known as foot-candles (fc) one foot candle equals the amount of light that falls on one square foot of surface located one foot away from one candle.watts per square foot is easy to calculate but is erroneous way to calculate usable light for a garden. It measures how many watts are available from a light source in an area.mounting height is not considered in watts per square foot, nor does it consider PAR watts or efficiency of the bulb.Calculating foot candles or lux is a more accurate way to estimate the amount of light plants recieve, but it still lacks the precision of a light meter that calculates foot candle or lux. PAR and light spectrum play a huge role in growth rates. Marijuana needs light to grow. the light must have the proper spectrum and intensity to ensure rapid growth. light is comprised of several bands of color. Each color in the spectrum sends the plant a seperate signal each colr in the spectrum promotes a different type of growth. Plants need and use only certain portions of the light spectrum however, and the most important colors in the spectrum for maximum chlorophly production and photosynthesis response are in the blue and red range. The main portiion of light used by plants is beetween between 400-700 nonometers (nm) this region is called the Photosynthetically active radiation (PAR) zone. PAR watts is the measurement of the actual amount of specific photons a plant needs to grow. Photons are a measure of light energy. Light energy is radiated and and assimilated in photons. Photosynthesis is nesassary for plants to grow is activated by the assimilation of photons. blue photons are worth more PAR watts than red photons, but scientists have difficulty measuring the exact difference.Each color of light triggers different plant functions. Positive tropism, the plant ability to to orient leaves towards light, is controlled by spectrum. while light bulbs will never really be as good for plants as the sun it is sufficient enough.Light is also measured in Keulvin temperature which expresses the exact color a bulb emits (almost always on the box of bulb) bulbs with a kelvin temperature from 3000-6500 are best for growing marijuana. The PAR expalins that that plants use specific portions of the light spectrum a complete range from blue to red. Lamps with a spectrum similar to a PAR rated bulb can use Kelvin temperature of a bulb to ascertain the aproximate PAR rating for a bulb. The Color Corrected Temperature (CCT) of a bulb is the peak kelvin temperature at wich the colors in a bulb remain stable. We classify bulbs by thier CCT rating wich tells us the overall color of the light emmited. Companies use a Color Rendering Index, the higher the rating the better the bulb.
