LED LIGHTS THE ACTUAL TRUTH!

Heyho,
the Picture Shows what i thought there:

Warm Air can hold more water vapor, so the same amount of water in warmer air leads to a decrease in rel H.
If you now further decrease the temperature than 10°C, then relative humidity would stay at 100% but the water would condense, decreasing the absolute amount of water in the air.

^^^^^ its called the dew point.

hyroot said:

^^^^^ its called the dew point.

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do you agree with me or not?

I dont claim im right, its just what I think.

SDS, wikipedia: "If the temperature rises in conditions of constant pressure, then the dew point will remain constant but the relative humidity will drop."

Maybe those IR beams are HPS' secret Sauce

lax123 said:

Heyho,
the Picture Shows what i thought there:

Warm Air can hold more water vapor, so the same amount of water in warmer air leads to a decrease in rel H.
If you now further decrease the temperature than 10°C, then relative humidity would stay at 100% but the water would condense, decreasing the absolute amount of water in the air.

Click to expand...

Yes ,it is correct ...
As long there's no changes in the total amount of water vapor ....
At this case you describe ,water mass stays the same (unchanged).

In a grow situ ,things won't not work that ' ideally' ...
As temperature rises new water (from plant tissue & medium ) molecules are added to
vapour ...As warm air can hold more water vapor-the amount of water in warm increases .


...

"Reducing the absolute humidity without changing other variables will bring the dew point back down to its initial value. In the same way, increasing the absolute humidity after a temperature drop brings the dew point back down to its initial level. If the temperature rises in conditions of constant pressure, then the dew point will remain constant but the relative humidity will drop. For this reason, a constant relative humidity (%) with different temperatures implies that when it's hotter, a higher fraction of the air is water vapor than when it's cooler."

I think, if I increase the temp , the rH% decreases more quickly compared to what is immediately vaporized...
This difference creates a driving force that makes the plants transpire more. Yes, slowly over time the rH% will rise again, upon reaching the same rH% as before the temp increase u now have much more water in the air
What happens at lights off, with that amount of additional water, as temperature falls...I imagine bad things like fungus.

But that just shows me that i have not thought it all through
What happens now?

At 30°C and 55%rH the VPD is significantly higher then at 20°C and 55% rH
link: VPD table

As VPD is higher, it should make the plants transpire more then at lower temp with same rH. now I have to think about what that means or if thats even true lol

Anyway,I like your hypothesis ..
Search a bit more thoroughly ...
If it really stands as true ...
Then I reaaaallllyyyyy like your hypothesis !

Cheers.

So what rh should I have my room/tent set at for the best results?.. and if its not the same for every grow. What are the variables?

Yea that thought about what could be done with led is one thing...I guess I should put that aside for now.
I think its more important to clearify how (beneticial) the effects of increased temperature on leaves are induced by hps IR beams.
Because light + IR-increased-leaf-temp reminds me of what plants adapted to -the sun.

Or as you didnt say anything about the first part of what I wrote in the hypo -maybe you all already know? If not I will search for more info regarding that part.


Holyghost:
http://www.just4growers.com/media/1315/vapor_pressure_deficit_relative_humidity_chart_small.jpg
I think anything in the orange range would be good.

HolyGhost23 said:

So what rh should I have my room/tent set at for the best results?

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Keep your rh between 30%-35% and you'll be fine.
Go any higher and you're seriously increasing the risk of mold.

stardustsailor said:

Can you explain /analyse why this will happen ?


I had the impression that exactly the opposite happens .
I've always thought that lower temps translate to lower Rel.humidity ...

Below zero Celcious ,air is totally dry . 0% rel.hum.
Water vapour has solidify into ice particles and dropped ,due to gravity ...


Less energy given,lower the energy state of matter .
If you apply heat ,water molecules start to 'move' faster .
At one point they're 'escaping' the 'matrix' of the liquid state.
They become Vapour.Gas state.

Subtract energy ,and motion becomes less .
Water molecules form a 'still' crystal matrix.
Ice .Solid state ..

Explain please ,how-contrary to thermodynamic laws-you will increase heat and the rel. humidity will
decrease ...

While evaporation of all water molecules around ,will be increasing,how on Earth rel.humidity will decrease ?
.....

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Below 0 deg C, there is still humidity in the air. Warmer air can hold more water. So the RELATIVE humidity goes down unless you add more water. You've been laboring under a false impression.

PSUAGRO. said:

You are correct SDS..............most damage done to perennials isn't just the cold, it's the low RH drawing moisture out of the leaves that causes severe necrosis.

big reason citrus growers spray water on the fruit before frost (RH retension)

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They spay water to prevent the fruit from freezing. And SDS had it completely backwards, too.

Red1966 said:

They spay water to prevent the fruit from freezing. And SDS had it completely backwards, too.

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Backwards? What do you think frost does? Lol......maybe you should read my post again and study what the rh levels are during a freeze....

I do food crop management for a fucking living...............not in the citrus industry and underqualified, but still

PSUAGRO. said:

Backwards? What do you think frost does? Lol......maybe you should read my post again and study what the rh levels are during a freeze....

I do food crop management for a fucking living...............not in the citrus industry and underqualified, but still

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Yeah, backwards, as in: rH goes down as temp goes up. I just repeat what farmers tell me every year, but what do they know?

PSUAGRO. said:

Backwards? What do you think frost does? Lol......maybe you should read my post again and study what the rh levels are during a freeze....

I do food crop management for a fucking living...............not in the citrus industry and underqualified, but still

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the golf course grows their own veggies lol

All I remember is that when it got down to freezing in CO there was zero RH. Almost fkn killed me. Made some nice sparks with static electricity and a wool blanket though

Mohican said:

All I remember is that when it got down to freezing in CO there was zero RH. Almost fkn killed me. Made some nice sparks with static electricity and a wool blanket though

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Even the driest deserts rarely fall below 14%rH. Zero humidity WOULD have killed you. I think you're mistaken.

Red1966 said:

Yeah, backwards, as in: rH goes down as temp goes up. I just repeat what farmers tell me every year, but what do they know?

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OHHH here we go, that's a nice blanket statement^^............No disrespect to the "farmers" you talk too, but they can say/do dumb things as the rest of us.........trust me on that. I've heard/seen some crazy shit out there

First of all it depends on the zone/regions your farmers are in(give some specifics!) and some other factors(not including micro climates)

IF your farming in a TEMPERATE zone high rh issues are only faced in the WARMER months leading to the heavy use of fungicides......Transpiration rates increase, and water is applied more often=== raising the RH levels around the crops, hence defoliation//chems to combat this. There are exceptions to this as well....

-Ask any seasoned grower when they usually face high RH conditions SUMMER or WINTER(indoors or outdoors)??? not gonna like the answer me thinks

- when you turn on your AC, what does it do to the room's rh conditions?? your not gonna like that answer

- stick your hygrometer into the freezer then into the warmer refrigerator/ check the rh levels??? your not gonna like the answer either....what causes freezer burn again?? maybe I'm just a stupid field worker and think it's something else.

- water is applied to fruits to prevent FREEZING/ MAINTAIN THE MOISTURE CONTENT(RH) , which is why I said to read my earlier post again

I'm not gonna argue with you anymore, there are general guidelines when working outdoors and in my case it's all relevant to where I live/work.

hyroot said:

the golf course grows their own veggies lol

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That US open was for a FREE consultation(friend works at Merion), couldn't help with the issue and they brought in the REAL pros from Rutgers(turf management).

PSUAGRO. said:

That US open was for a FREE consultation(friend works at Merion), couldn't help with the issue and they brought in the REAL pros from Rutgers(turf management).

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lucky son of a bitch....