14x1750=1750 WTF, Small Cfl Array, Input Appreciated

C_Pac said:

Thanks much.

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C_Pac said:

What do you mean by 'foliar penetration'?

Do you mean light getting past the canopy to lower leaves? Or do you mean light penetrating outer leaf tissues or something to be used as energy by the plant?

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Photosynthesis uses light energy and carbon dioxide to make triose phospates (G3P). G3P is generally considered the prime end-product of photosynthesis. It can be used as an immediate food nutrient, or combined and rearranged to form disaccharide sugars, such as sucrose and fructose, which can be transported to other cells, or packaged for storage as insoluble polysaccharides such as starch.

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    6 CO2(g) + 12 H2O(l) + [B]photons[/B] → C6H12O6(aq) + 6 O2(g) + 6 H2O(l)
    carbon dioxide + water + [I]light energy[/I]→ glucose + oxygen + water

When written as a word equation the light energy appears above the arrow as it is required for photosynthesis but it is not actually a reactant. Here the monosaccharide glucose is shown as a product, although the actual processes in plants produce disaccharides.

The equation is often presented in introductory chemistry texts in an even more simplified form as:[2]

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    6 CO2(g) + 6 H2O(l) +[B] photons[/B] → C6H12O6(aq) + 6 O2(g)

Photosynthesis occurs in two stages. In the first phase, light-dependent reactions or photosynthetic reactions (also called the Light reactions) capture the energy of light and use it to make high-energy molecules. During the second phase, the light-independent reactions (also called the Calvin-Benson Cycle, and formerly known as the Dark Reactions) use the high-energy molecules to capture carbon dioxide (CO2) and make the precursors of carbohydrates.

In the light reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, allowing the start of a flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP into NADPH. In addition, it serves to create a proton gradient across the chloroplast membrane; its dissipation is used by ATP Synthase for the concomitant synthesis of ATP. The chlorophyll molecule regains the lost electron by taking one from a water molecule through a process called photolysis, that releases oxygen gas.


In the Light-independent or dark reactions the enzyme RuBisCO captures CO2 from the atmosphere and in a process that requires the newly-formed NADPH, called the Calvin-Benson cycle releases three-carbon sugars, which are later combined to form sucrose and starch.

Photosynthesis may simply be defined as the conversion of light energy into chemical energy by living organisms. It is affected by its surroundings and the rate of photosynthesis is affected by the concentration of carbon dioxide, the intensity of light , and the temperature.

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Maccabee said:

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Al B. Fuct said:

ZOMFG... not the CALVIN CYCLE!!

aieeeeeeeeeeee......

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Tanuvan said:

Film is measuring light isn't it?

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Tanuvan said:

All of this bulb moving crap can be mediated with a Scrog setup....The results even out.

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No one has yet to say why dense buds are better than the supposed airy buds of CFL. 8 oz of dense bud vs 8 oz of airy bud...is still 8 oz of bud...it still smokes...still makes hash...still makes oil...Am I missing something?

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Maccabee said:

It's measuring light, but not necessarily its intensity. Look at the chemical equation for photosynthesis: that reactions happens for each photon, not once the photon bucket fills to a certain point. When you carry out the reaction with a higher energy photon, you get more out of it. Or maybe it costs less, making it more efficient. I'm a little vague there.

Furthermore, using higher energy photons helps deliver light to more areas, as adding point sources only goes so far. Every square inch of photosynthetically active tissue can't be brought to within an inch of the CFL tube.


More intense light is better. Increasing the amount of light delivered also helps, up to a point. Increasing the number of lights can increase the amount of light delivered, but there is also a logistical limit there. So you're working within the limit of benefit possible to derive from increased light volume, and then within the smaller yet limit of how how to practically approach that theoretical limit.

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Tanuvan said:

"

This is only the case for point light sources like HID. The greatest lux is closest to the bulb because the light is emanating from one spot.

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Tanuvan said:

GK has proven without a doubt as well as many other growers that Flouros can produce very well over small grows which a good majority of people on here do anyway. Just don't use flouros like an HID.

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Maccabee said:

That's true, but GK defers to Al when it comes time to explain the whys and hows of lumens, lux, etc.

Don't use flouros like an HID....and don't expect the same growth profile.

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Tanuvan said:

It isn't the case for all sources. Just point sources of light. HID has photons radiating from a central localized area. The light distribution is vastly different than a flouro tube. CFL including straight tubes radiate light along the entire surface area...which is why they give the impression of being physically cooler lights.

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Maccabee said:

How does that inhibit the operation of the inverse square law as the observation point is moved away from the emitter surface? The inverse square law still operates when HID light is diffused by a reflector, altering the patter of distribution of the radiated energy from that of a naked bulb hanging on a cord.

I'm no physics genius, but I don't think what you're saying is quite on point. It's true--but not really on point. Meh. I feel like calling someone up from college and hassling them about it, but then they'd want to know why.

Maybe we should go try and rope somebody from the XKCD forums in.

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Light and other electromagnetic radiation

The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only ¼ the energy (in the same time period).

More generally, the irradiance, i.e., the intensity (or power per unit area in the direction of propagation), of a spherical wavefront varies inversely with the square of the distance from the source (assuming there are no losses caused by absorption or scattering).

For example, the intensity of radiation from the Sun is 9140 watts per square meter at the distance of Mercury (0.387AU); but only 1370 watts per square meter at the distance of Earth (1AU)—a threefold increase in distance results in a ninefold decrease in intensity of radiation.

Photographers and theatrical lighting professionals use the inverse-square law to determine optimal location of the light source for proper illumination of the subject.

The fractional reduction in electromagnetic fluence (&#934 for indirectly ionizing radiation with increasing distance from a point source can be calculated using the inverse square law. Since emissions from a point source have radial directions, they intercept at a perpendicular incidence. The area of such a shell is 4πr2 where r is the radial distance from the center.

The law is particularly important in diagnostic radiography and radiotherapy treatment planing, though this proportionality does not hold in practical situations unless source dimensions are much smaller than the distance r.

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Field theory interpretation

For an irrotational vector field in three-dimensional space the law corresponds to the property that the divergence is zero outside the source. Generally, for irrotational vector field in n-dimensional Euclidean space, inverse (n − 1)th potention law corresponds to the property of zero divergence outside the source.

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  Quantity     Symbol     SI unit     Abbr.     Notes
Luminous energy     Qv     lumen second     lm·s     units are sometimes called talbots
Luminous flux           F     lumen (= cd·sr)     lm     also called luminous power
Luminous intensity     Iv     candela (= lm/sr)     cd     an SI base unit
Luminance         Lv     candela per square metre     cd/m2     units are sometimes called nits
Illuminance         Ev     lux (= lm/m2)     lx     Used for light incident on a surface
Luminous emittance     Mv     lux (= lm/m2)     lx     Used for light emitted from a surface
Luminous efficacy           lumen per watt     lm/W     ratio of luminous flux to radiant flux; maximum possible is 683.002 lm/W

 Quantity     Symbol     SI unit     Abbr.     Notes
Radiant energy     Q     joule     J     energy
Radiant flux     Φ     watt     W     radiant energy per unit time, also called radiant power
Radiant intensity     I     watt per steradian     W·sr−1     power per unit solid angle
Radiance     L     watt per steradian per square metre     W·sr−1·m−2     power per unit solid angle per unit projected source area  Sometimes confusingly called "intensity".
Irradiance     E     watt per square metre     W·m−2     power incident on a surface. Sometimes confusingly called "intensity".
Radiant exitance/emittance     M     watt per square metre     W·m−2     power emitted from a surface.
Radiosity     J or Jλ      watt per square metre     W·m−2     emitted plus reflected power leaving a surface
Spectral radiance  Lλ o rLν watt per steradian per metre3 or watt per steradian per square metre per hertz    W·sr−1·m−3 or W·sr−1·m−2·Hz−1 commonly measured in W·sr−1·m−2·nm−1
Spectral irradiance Eλ or Eν     watt per metre3 or watt per square metre per hertz  W·m−3 or W·m−2·Hz−1 commonly measured in W·m−2·nm

The lumen is the photometric unit of light output. Although most consumers still think of light in terms of power consumed by the bulb, in the U.S. it has been a trade requirement for several decades that light bulb packaging give the output in lumens. The package of a 60 watt incandescent bulb indicates that it provides about 900 lumens, as does the package of the 15 watt compact fluorescent.


The lumen is defined as amount of light given into one steradian by a point source of one candela strength; while the candela, a base SI unit, is defined as the luminous intensity of a source of monochromatic radiation, of frequency 540 terahertz, and a radiant intensity of 1/683 watts per steradian. (540 THz corresponds to about 555 nanometres, the wavelength, in the green, to which the human eye is most sensitive. The number 1/683 was chosen to make the candela about equal to the standard candle, the unit which it superseded).


Combining these definitions, we see that 1/683 watt of 555 nanometre green light provides one lumen. [Thus, the lumen scale is calibrated to a point in the spectrum that photosynthesis doesn't use -- Mac]


The relation between watts and lumens is not just a simple scaling factor. We know this already, because the 60 watt incandescent bulb and the 15 watt compact fluorescent can both provide 900 lumens.


The definition tells us that 1 watt of pure green 555 nm light is "worth" 683 lumens. It does not say anything about other wavelengths. Because lumens are photometric units, their relationship to watts depends on the wavelength according to how visible the wavelength is. Infrared and ultraviolet radiation, for example, are invisible and do not count. One watt of infrared radiation (which is where most of the radiation from an incandescent bulb falls) is worth zero lumens. Within the visible spectrum, wavelengths of light are weighted according to a function called the "photopic spectral luminous efficiency." According to this function, 700 nm red light is only about 4% as efficient as 555 nm green light. Thus, one watt of 700 nm red light is "worth" only 27 lumens. [This suggests to me that lumen ratings would be misleading for comparing, say, HPS to CMH. CMH is much greener light, and will appear to be 'worth' more lumens, even though it should be less useful to flowering Cannabis.-Mac]

Because of the summation over the visual portion of the EM spectrum that is part of this weighting, the unit of "lumen" is color-blind: there is no way to tell what color a lumen will appear. This is equivalent to evaluating groceries by number of bags: there is no information about the specific content, just a number that refers to the total weighted quantity.

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