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Light: Difference between revisions
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=== μmol/s ===
The measure of photons per second produced by a light. Photons are measured in micro (10^-6) [https://en.wikipedia.org/wiki/Mole_(unit) moles] there are a huge amount of photons coming from any light source. One µmol is actually 602 quadrillion photons. Simply put, this metric is the intensity per second from a light.
=== μmol/J ===▼
The light intensity a horticultural light produces per Joule of power it uses. This is a measure of its efficiency. At the time of writing, the most efficient LED package available is the [https://www.samsung.com/led/lighting/mid-power-leds/3030-leds/lm301h/ LM301H] by Samsung. It achieves 3.10 μmol/J @ 65 mA, 25°C. Note the efficiency will change depending on the temperature and current supplied.▼
=== PPFD ===
Photosynthetic Photon Flux Density: its unit is μmol/m^2/s. It is a measure of light intensity over an area per second. This is important to note when buying a grow light. For example, light A may provide an intensity of 800 μmol/s in a 1m^2 area, while light B provides the same intensity in a 4m^2 area. Light B provides the same intensity but over four times the area, so it can support a larger plant. In this case, light B has a greater PPFD.
▲=== μmol/J ===
▲The light intensity a horticultural light produces per Joule of power it uses. This is a measure of its efficiency. At the time of writing, the most efficient LED package available is the [https://www.samsung.com/led/lighting/mid-power-leds/3030-leds/lm301h/ LM301H] by Samsung. It achieves 3.10 μmol/J @ 65 mA, 25°C. Note the efficiency will change depending on the temperature and current supplied.
=== DLI (Daily light Intergral) ===
The amount of light energy (photons) a plant is receiving every 24 hours. For example, if you used a light with a PPFD of 500μmol/m^2/s on a 20/4 lighting schedule that would result in a DLI of 43.20. [https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator DLI calculator]
Full light intensity from the sun in summer reaches around 60 DLI<ref>https://www.youtube.com/watch?v=ID9rE5JewVg&t=1170s&ab_channel=ApogeeInstrumentsInc. - Bruce Bugee Grow lighting myths</ref>
== Horticulural light terms ==
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