Natural drying observation

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Butterbean
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Natural drying observation

Post by Butterbean » Wed Jan 27, 2016 02:34

This may be of little interest to those using curing chambers but to anyone not this might be as interesting to you as it is to me. As you may know I rarely use a curing chamber and have gone to curing meats with the weather since I live in an area that typically has high humidity.

I've been monitoring my ambient temps and humidity with a little instrument I found at Home Depot and it gives the max and min of the temps and the humidity so its been easy enough to monitor the curing.

Anyhow, I've been monitoring things for the last couple of weeks and found something interesting yet somewhat puzzling. Based on the readings when the temperature increases through the day so does the humidity. While I wasn't the best pupil in hydrology and that was many years ago this just seemed wrong and goes against the accepted relationship between temp and humidity.
If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.
Anyway, what I found in my situation is the exact opposite. When the temp was at 50F the humidity was at 60% but when the temp increased to 60F the humidity rose to 78% - or about a 2% increase for each degree of temp increase and vice versa. I thought this interesting. The only explanation I can think of is when the temperature increases so does evaporation which puts more water vapor in the air.

If my understanding is correct then this little quirk of nature is really helpful in curing meats since I would think at higher temperatures the meat will dry faster and would require a higher humidity to prevent case hardening and less humidity at lower slower drying rates. I don't know if this is right but it seems logical. At any rate, I just thought it interesting and thought it worth sharing and maybe someone can add to this observation because there is so much I'd like to know.
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redzed
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Post by redzed » Wed Jan 27, 2016 07:38

OK, that is interesting, but how do you know that your water vapour is the same for both measurements? I think in Marianski's yellow book there is a section discussing the ambient RH during different times of day and there wide swings. I think that what you quoted might refer to a very controlled environment. But then I'm only speculating. Might have to do some reading.
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Post by Butterbean » Wed Jan 27, 2016 13:18

I don't know the water vapor is the same even though I'm doing nothing different. Apparently its not for it to give these numbers. I'm guessing its increasing with the temperature increase from additional evaporation or something. I'll do some reading in the yellow book and see if he answers this too.
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Now it's clear as mud, I bet

Post by el Ducko » Mon Feb 01, 2016 20:53

What`s happening is that, when the sun comes out, water evaporates, driven by the sun`s heat. Also, the plants give off more water during the day than the night, due to their photosynthesis activity. As I recall from my South Georgia pulp & paper days, maybe those gigantic mosquitoes of yours stir it up, too. (They sure thrive in it!)

At any rate, it`s a race between evaporation rate adding water to the atmosphere and the rising air temperature increasing the amount of water that it can hold.

Spoiler alert: For those brave souls who want to venture further, keep on reading. For most of us, this is a good stopping place.

I am attempting to attach an example of a "psychrometric chart"which can be found on the internet at (http://me.queensu.ca/Courses/MECH330/Ps ... ica_SI.pdf) http://me.queensu.ca/Courses/MECH330/Ps ... ica_SI.pdf This thing is a diagram of how much water vapor the air can hold at various temperatures. ...nightmarish, huh? This is what us old-timers used to use before computers took over the engineering calculations. (Slide rule, anyone?) Anyway, the attachment display isn't large enough, so I suggest you download the thing and make it larger in your PDF reader.

Anyway, across the bottom horizontal axis is dry bulb temperature. Let`s say it`s 20 degC out there. If you go vertically along that 20 degree line (constant dry bulb temperature) until you hit the curve (where wet bulb and dry bulb temperature are the same), that`s 100% humidity. If you haven`t gone cross-eyed yet, note that you can read off how much water is in the air by looking horizontally at the "Humidity Ratio" scale, which is grams of water per kilogram of dry air. This is the heart of the diagram. The rest is just window dressing but, like a well-dressed window display during the holiday season, gives you oh so much more.

Had enough, yet? Now, let`s try heating our 100% humidity saturated air with sunshine. If you could somehow not add any water, you would move horizontally to the right, and you can see that as the temperature goes up, you cross the relative humidity lines, meaning that the relative humidity goes down. We`re going horizontally, meaning that we`re not adding any water, but the ability of the air to hold more water goes up as the temperature increases (and as your eyes start to glaze over).

But hang on! There`s nothing to stop pond water and tree water from evaporating and entering the air. Suppose that it`s plenty steamy and there`s plenty of sunshine, which reminds me of a morning in southeast Arkansas where I grew up. Yuk. If water can enter the air freely, meaning that plenty of heat is available, this time we`ll move up along the 100% relative humidity curve, that outer one to the left.

As you add heat (which is symbolized by the enthalpy scale on the far right, but that`s a fancy word, so let`s ignore that!), temperature rises, as you can see by the (slanted downward to the right) temperature lines that you`re passing by as you go up along that saturation curve. Let`s suppose that the temperature rises to a steamy 25 degC at 100% humidity. The amount of water vapor, grams per kilo of dry air (scale on the right) has gone from about 15 to about 20 grams/kilo of dry air as the swamp water evaporates. (You can juggle the math to see how much heat you had to add to do that, but let`s not go overboard just yet.)

Confused yet? But wait! There`s more! There`s reality, up there ahead, just around the bend. (...struggling sounds as guys in white coats enter, wrestle the Duck to the ground, and wrap him in a straight jacket.) What actually happens is part way between the two cases of (1) temperature going up without adding water vapor, and (2) temperature staying constant with water vapor being (in this case) removed.

Somewhere in between lies "the truth," and it`s determined by how fast water can condense or evaporate, phase of moon and height of tide, and your mother-in-law`s... Well, you get it. The chart shows a static condition called equilibrium, but the real world is dynamic and never quite gets there. As they say on the X Files TV series, the truth is out there somewhere.... And I bet it`s mosquito infested, wherever it is.
Now, back to our regularly-scheduled... AWKKK! Hey! Don`t...
Duk
:mrgreen:http://me.queensu.ca/Courses/MECH330/Ps ... ica_SI.pdf http://me.queensu.ca/Courses/MECH330/Ps ... ica_SI.pdf
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Post by redzed » Wed Feb 03, 2016 00:53

Thanks Ducko, a bit clearer now. :lol: And I always suspected that swamp!
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Post by Butterbean » Wed Feb 03, 2016 01:24

Thanks for the explanation! You saved me having to write our local meteorologist. He's a good guy, although he isn't worth a hoot at predicting haying weather, but he will answer stuff like this via e-mail but no need to bother him now.

I had a hunch that rule was for a closed system but in nature it isn't closed. I had an epiphany about this a few years ago after I started monitoring my ambient temps and humidity and found that while nature would not allow me a steady curing temp or curing humidity it would give me acceptable ranges to cure meat through most months of the year.

When I stopped using my chamber many of my problems went away and it seemed all too simple. My biggest problem at first was wild molds. And the swamp has many of them but thanks to a customer and friend who is a retired microbiologist my fears of "off color" molds were soon put to rest. But with time, my "closed system" aka my barn is full of white mold - white swamp mold for sure. It gets on anything I don't smoke or wipe down with vinegar. (Just cutting the fool about it being swamp mold. I know where I got it. I bought it and inoculated a few batches and it has since taken over.)

Now my next hunch is, that anyone who is first getting into curing via a chamber or whatever will typically have problems with wild molds till they build up an onsite spore inventory and when this happens life will get simpler after each curing because not everyone has a local spore expert who can just look at it and say - don't worry. I know I worried enough at one point. Not that I'm being discriminatory about the color of mold because I learned just because a mold has color doesn't necessarily make it bad and I had some colorful stuff at one time. Slime is what he cautioned.
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Post by el Ducko » Wed Feb 03, 2016 05:00

Butterbean wrote:...My biggest problem at first was wild molds. And the swamp has many of them but thanks to a customer and friend who is a retired microbiologist my fears of "off color" molds were soon put to rest. But with time, my "closed system" aka my barn is full of white mold - white swamp mold for sure. It gets on anything I don't smoke or wipe down with vinegar. (Just cutting the fool about it being swamp mold. I know where I got it. I bought it and inoculated a few batches and it has since taken over.)

Now my next hunch is, that anyone who is first getting into curing via a chamber or whatever will typically have problems with wild molds till they build up an onsite spore inventory and when this happens life will get simpler after each curing because not everyone has a local spore expert who can just look at it and say - don't worry. I know I worried enough at one point. Not that I'm being discriminatory about the color of mold because I learned just because a mold has color doesn't necessarily make it bad and I had some colorful stuff at one time. Slime is what he cautioned.
Aha! In my vast experience of one batch in a new "closed system"... well... uh... I feel better now. ...I think. The second batch, this time with a healthy squirt of Mold-600, looks lots better (whiter) than that first batch with the patches of blackish-green slime. I wiped 'em off with vinegar, and vowed never to tell anyone. So maybe confession IS good for the soul, huh? (...and not as bad for the health as I had worried.) Thanks, BB.
Duk :mrgreen:
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Post by Butterbean » Wed Feb 03, 2016 14:46

Confessions are good I think. Some anyway. Have you made any where the mold looked like a tie - dyed t-shirt at Woodstock? I have so I got that going for me I guess. But seriously, it seems harder and harder to grow any "colorful" molds.

I was chastised and accused of having some agenda a while back. It was puzzling. Maybe I came across as arrogant when I was only speaking from my experience and in my small world my experience is at such a level that I am able to immediately recognize my mistakes when I make them again. I eventually hope to learn.
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Post by el Ducko » Wed Feb 03, 2016 15:02

Butterbean wrote:Confessions are good I think. Some anyway. Have you made any where the mold looked like a tie - dyed t-shirt at Woodstock? I have so I got that going for me I guess. But seriously, it seems harder and harder to grow any "colorful" molds.

I was chastised and accused of having some agenda a while back. It was puzzling. Maybe I came across as arrogant when I was only speaking from my experience and in my small world my experience is at such a level that I am able to immediately recognize my mistakes when I make them again. I eventually hope to learn.
Maybe that's why my green-n-black mold looked like camouflage- - I was in the army during the Woodstock days. Hmmm... cause-and-effect? Maybe we're on to something here.
...maybe even an agenda? :mrgreen:
Anyway, thanks for the help.
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Post by Butterbean » Wed Feb 03, 2016 23:56

No. THANK YOU for your input on this humidity thing. It explains a lot and in a natural system its almost like nature's variations breathe life into a piece of meat. I'm sure your camo colored spores probably came from hill 65 or thereabouts just like mine are swamp spores. lol

As to agendas, the only one I have is complete world domination. lol Or is that universal domination. I get confused as I often lack direction.
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