Fun with thermometers in Oz 3

[waross]

As for pushing water into the atmosphere without heat? Have you not seen an ice cube waste away to nothing in your freezer? Sublimation only requires temperature above absolute zero, no heat addition.

You just blew your credibility out the window with this one, Tug.
That ice cube is not sublimely immune to the latent heat of fusion and the latent heat of vaporization.

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Ohm's law
Not just a good idea;
It's the LAW!

 

[TugboatEng]

I don't understand? At any temperature above absolute zero sublimation is going to occur. It doesn't require heat addition or removal, it just requires heat presence.

In other words, if you hold ice at a constant temperature, eventually you won't have any ice anymore.

 

[dik]

I don't know much about absolute zero, but from grade school, I thought it was the absence of heat?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TugboatEng]

That is correct.

Waross?

 

[waross]

Heat as measured in BTUs is exchanged when water changes state.

Latent heat is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process — usually a first-order phase transition. Latent heat can be understood as hidden energy which is supplied or extracted to change the state of a substance without changing its temperature or pressure.

Don't let this statement excite you;
"state of a substance without changing its temperature or pressure."
The ice stays at a constant temperature, 32degrees F.
The BTUs come from the surrounding air.
I thought that everyone knew that.
Was that information lost in California as a victim of Reagan's cuts to the educational budget?
Sublimation and evaporation have more to do with vapour pressure than with temperature, but still require BTUs.
Gee wizz. I think that the rancher has shipped his bulls and all that's left is .......


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[dik]

I seem it requires 80 calories to go from liquid to solid without changing temperature.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TugboatEng]

Sublimation isn't a constant temperature process...

 

[SwinnyGG]

Sublimation isn't a constant temperature process...

Let's say that's true for a second.

Sooo.. you think there can be a temperature change without any heat being absorbed?

 

[dik]

I don't know what if any thermal transfer (either one way or the other) is required with sublimation or regulation... I suspect there has to be some, but don't know.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TugboatEng]

I don't know what concept you are missing. Sublimation is a loss of heat but doesn't require heat addition. Frozen water can sublimate at any temperature.

 

[dik]

...at absolute zero? I dunno... and I don't know if there is or isn't some kind of heat transfer.

In gradeschool, we were taught the temperature was a measure of the average speed of the molecules (ignore Planck and Quantum Mechanics, this was long before him).

I suspect the molecules leaving are some of the faster ones, and the average speed of those remaining would be less (if you recall, evaporation (something similar, but different than sublimation) is a cooling process (I think Grade 7, but no longer sure)).

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SwinnyGG]

Sublimation is a loss of heat but doesn't require heat addition

Sublimation is an endothermic process. End of story. I don't know where you're getting your information from but it's wrong.

 

[BridgeSmith]

Are we really arguing over sublimation at absolute zero? Can't we find something more constructive to do than trying to win an irrelevant theoretical argument, just to make someone else look bad?

 

[TugboatEng]

SwinnyGG, if you take an ice cube at 0°F and place it in a freezer at 0°F it still sublimates. Where is the heat coming from if there is no temperature differential?

 

[JoshPlumSE]

It should be fairly easy to determine the temperature of an object and corroborate what the 'real' temperature is; it shouldn't matter what method you use, but you will have the 'real' temperature. Whether the object is representative of what you are trying to measure is another issue.

That's where you're sooooo wrong. This is not an easy task. There is a mountain of data coming from different sites with different equipment, different surroundings and such. Correlating / correcting this data is NOT an easy task at all. Especially when you're also correlating it to imperfect historical data. And, one of the biggest issues is that this data collection is mostly "black box" where some group assembles it and releases it, but won't tell you what into making the sausage. They just tell us all to trust the final sausage. They don't want it reviewed. They fear that. This is the type of GRU scandal that I was talking about in a previous thread.

I'm not someone who believes there is a genuine conspiracy to inflate the numbers or such. However, climate change is almost like a religion. So, when the GRU had internal e-mail exchanges relating to how to "hide the decline", it was a big deal. Then they couldn't explain the methodologies they used to adjust the raw data.... These sorts of things are the reasons why we have to balance the "science" with the economics.

 

[dik]

could be... I dunno. I was guessing that with the loss of the faster molecules, those remaining would be cooler. I don't know what the reaction is to make it endothermic.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

I don't know much about sublimation... and it's a learning process. We're not quibbling. If I knew, I'd simply stipulate.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

OK... There have to be 'a dozen' ways to take the temperature of an object... as long as the method is identified and the temperature is repeatable, then it's OK with me. A different method may yield a different temperature, but as long as it's repeatable, then the two methods can be compared... noting whatever differences there are.

No rocket science...

Whatever scale you are using and whatever method, things are definitely heating up.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SwinnyGG]

Are we really arguing over sublimation at absolute zero? Can't we find something more constructive to do than trying to win an irrelevant theoretical argument, just to make someone else look bad?

You're right that this is a pedantic argument- but I'd argue that incorrectly arguing a scientific point which is well known says A LOT about the person making the argument. From my point of view at least, it's got nothing to do with making any one look bad. But it does have a great deal to do with pointing out a non-scientific point of view that's present in a conversation that should be mostly about data.

 

[SwinnyGG]

SwinnyGG, if you take an ice cube at 0°F and place it in a freezer at 0°F it still sublimates. Where is the heat coming from if there is no temperature differential?

Ask yourself why your freezer has a compressor which runs all the time.

Seriously, this is well understood. It's not hard to figure out. You could learn this information yourself in about 10 seconds of googling.

https://chem.libretexts.org/Bookshe...s_and_Potentials/Enthalpy/Heat_of_Sublimation

https://www.chemistrylearner.com/heat-of-sublimation.html

https://www.chegg.com/learn/topic/latent-heat-of-sublimation

https://www.w3schools.blog/standard-enthalpy-of-sublimation