OldMedUser
Well-Known Member
Not all light frequencies create heat when the photons strike an object so that's not correct.
Air cooled?
- Thread starter sizzilky
- Start date
grotbags
Well-Known Member
so what happens to the photon then? it cant just vanish.
grotbags
Well-Known Member
@OldMedUser, why do we see the colour black?
OldMedUser
Well-Known Member
Photons of the different frequencies of the spectrum are absorbed by objects. Those not absorbed and reflected back are the colours we see that object as. Like pot plants are absorbing all the colours except green which is why they look green to our eyes.
Because the object is absorbing all the colours reflecting none back so it looks black. If it reflected all colours back it would appear white. That's why you paint things white that you want to stay cooler. Our sun actually appears white from space but the passage of it's light through our atmosphere absorbs some of the light spectrum making it appear yellow to our eyes. The more atmosphere it has to pass through before we see it absorbs more light changing the colour we see.
All eyes do not absorb light exactly the same so we all perceive colours slightly different from each other. The green you see reflected from your plant's leaves would be slightly different than how I perceive it but we would both agree the leaves were green.
As an example consider PAR light, (Photosynthetically Available Radiation), that is the gold standard to many when measuring light that falls on our plants. You could measure PAR from two lights made by different companies that read exactly the same yet plants grow better under one than the other. WTF, they should do the same if PAR was the only metric that counted but it's not. PAR measures the amount of light available in the frequencies of visible light that lay between 400 - 700 nanometers, (nm) but the plants only use certain frequencies in that range. One light may be higher in those frequencies eliciting a better growth response than the other that may be stronger in frequencies that the plant can't use so those photons are useless to the plants. Yet both give the same reading on the PAR meter.
Very sophisticated and expensive light measuring instruments can break the light down into it's various frequencies and measure the intensity of each. These are the kinds of instruments that light manufacturers such as Hortilux will use in their labs to fine tune the gas mixture used in their HID lights to better emit the frequencies that plants can use for optimal growth. I use a lot of their lights but have others in the same wattages and the Hortilux always give me the best looking plants. I just use a cheapo light meter to measure intensity so that I arrange my plants in the configuration that each is receiving that most amount of light it can. That is no measure of the quality of the light, just the amount that is available in that space.
I can go to the hardware store and buy a 400w HPS lamp for $35 and it will grow plants but when grown next to a $100 400W EYE Hortilux Super HPS that is tuned to emit more usable light the difference in growth is readily apparent to even the untrained eye.
Light, like pH, and other aspects of our hobby are very complex subjects that many books are written about by much more highly trained persons than myself. Tho I have spent thousands of hours delving into this fascinating hobby over the last 40+ years I still only know the basics.
Hope that clears some things up.
grotbags
Well-Known Member
i dont disagree with what you say but you dont address what happens to a photon once its absorbed.Photons of the different frequencies of the spectrum are absorbed by objects. Those not absorbed and reflected back are the colours we see that object as. Like pot plants are absorbing all the colours except green which is why they look green to our eyes.
Because the object is absorbing all the colours reflecting none back so it looks black. If it reflected all colours back it would appear white. That's why you paint things white that you want to stay cooler. Our sun actually appears white from space but the passage of it's light through our atmosphere absorbs some of the light spectrum making it appear yellow to our eyes. The more atmosphere it has to pass through before we see it absorbs more light changing the colour we see.
All eyes do not absorb light exactly the same so we all perceive colours slightly different from each other. The green you see reflected from your plant's leaves would be slightly different than how I perceive it but we would both agree the leaves were green.
As an example consider PAR light, (Photosynthetically Available Radiation), that is the gold standard to many when measuring light that falls on our plants. You could measure PAR from two lights made by different companies that read exactly the same yet plants grow better under one than the other. WTF, they should do the same if PAR was the only metric that counted but it's not. PAR measures the amount of light available in the frequencies of visible light that lay between 400 - 700 nanometers, (nm) but the plants only use certain frequencies in that range. One light may be higher in those frequencies eliciting a better growth response than the other that may be stronger in frequencies that the plant can't use so those photons are useless to the plants. Yet both give the same reading on the PAR meter.
Very sophisticated and expensive light measuring instruments can break the light down into it's various frequencies and measure the intensity of each. These are the kinds of instruments that light manufacturers such as Hortilux will use in their labs to fine tune the gas mixture used in their HID lights to better emit the frequencies that plants can use for optimal growth. I use a lot of their lights but have others in the same wattages and the Hortilux always give me the best looking plants. I just use a cheapo light meter to measure intensity so that I arrange my plants in the configuration that each is receiving that most amount of light it can. That is no measure of the quality of the light, just the amount that is available in that space.
I can go to the hardware store and buy a 400w HPS lamp for $35 and it will grow plants but when grown next to a $100 400W EYE Hortilux Super HPS that is tuned to emit more usable light the difference in growth is readily apparent to even the untrained eye.
Light, like pH, and other aspects of our hobby are very complex subjects that many books are written about by much more highly trained persons than myself. Tho I have spent thousands of hours delving into this fascinating hobby over the last 40+ years I still only know the basics.
Hope that clears some things up.
when a photon of any wavelength hits an object it can do two things its either absorbed or reflected/scattered.
if its absorbed then it depends on the composion of the material which has absorbed the photon as to what it does with that photon.
if its the right wavelength and its absorbed by a chloroplast in a plant cell then it will generate photosynthesis, if its absorbed by a solar panel it will generate electricity, if its absorbed by certain cells in the human body it will make vitamin d ect, ect...
but in our context its mostly hitting and eventually getting absorbed by inanimate objects like walls, floors ect, so it ends up as heat.
Rahz
Well-Known Member
I've get tips bleaching when running LEDs a little too close. Heat has never been an issue, though of course there are other factors accounted for.
I have used pin fins passively cooled on my lamp builds for years, but they are oversized. 150mm sinks for 45w output. But I still have some 200 watt fan cooled lamps I built maybe 7 years ago... still running strong. Extruded sinks with 120mm fans. I can put my finger on the sink right next to the cob and they're room temp. The case temps will be higher ofc but a room temp sink is a pretty good sign it's running well under spec. My over sized pin fin sinks are still pretty warm to the touch.
I have used pin fins passively cooled on my lamp builds for years, but they are oversized. 150mm sinks for 45w output. But I still have some 200 watt fan cooled lamps I built maybe 7 years ago... still running strong. Extruded sinks with 120mm fans. I can put my finger on the sink right next to the cob and they're room temp. The case temps will be higher ofc but a room temp sink is a pretty good sign it's running well under spec. My over sized pin fin sinks are still pretty warm to the touch.