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THE 3 forms of heat loss from an object or surface at earth's surface are...
#1
Hi All,

Oooops, it (it = heat transfer as presently taught / accepted) ain't
"radiation, conduction and convection"

It is,
Latent heat, conduction and then radiation,
all of which enhance or cause convection.

Convection is ("merely") a positive catalyst for latent heat and conduction losses.
Diffusion only is so much slower, isn't it.


Attached Files
.pdf   The 3 forms of heat transfer. Derek Alker.pdf (Size: 219.62 KB / Downloads: 292)
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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#2
Thread "stickied"..

Heat transfer and heat loss, not things that should be confused with each other really.
Doing so, could, well, cause a lot of "issues".......
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#3
Somewhere back in the Layman's thread I mention observing rocks in the desert cracking off their surfaces and spreading little shards of curved rock around.

This is an example of the temperature gradient failing to allow inner heat to reach the outer skin of the rock before heat loss to the atmosphere and radiation into the clear desert night sky caused the outer skin to shrink such that mechanical stresses split the skin into shards.

The term for this, I believe, is lapse rate. If heat transfer through a solid is slower than heat loss at the surface due to conduction, radiation and possibly evaporation then temperature measurement is not a good indication of the total heat remaining in the object. I feel lapse rate and time need to be considered in calculating heat transfer.

Another indication of the extent of this problem is that daily maximum air temperatures occur a couple of hours after the sun has passed zenith at that location. At night air temperature drops rapidly at first and then more slowly as surface heat moderates air temperatures.

At no point in time is anything, anywhere on this planet in a state of temperature equilibrium. Even at the bottom of the deepest oceans where time in the range of a thousand years or so must be considered. There are issues indeed. Smile
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#4
" Somewhere back in the Layman's thread I mention observing rocks in the desert cracking off their surfaces and spreading little shards of curved rock around. "

Geographically speaking I think you are referring to exfoliation, or onion skin weathering as it is sometimes called.
In all the explanations I have seen ice formation between the layers in the rock is a big part of the process, frost heave as such. Yes, some of the weathering is due to thermal tensions within the rock caused by cooling, but the majority of the weathering is usually describing as being due to ice formation and the pressure that creates within the rock.

" I feel lapse rate and time need to be considered in calculating heat transfer. "

Yes, a point I have tried to make before, but I have never seen done for gray body calculations.
It would soon prove radiation is over exaggerated in importance at present, that is why it is not done in my opinion.
It would be interesting to calculate the cooling of a body of water, because I am sure such a sum could not work at present.

" At no point in time is anything, anywhere on this planet in a state of temperature equilibrium. "

I think in my oily tray experiment I proved a body of water, open to the atmosphere, can never be in thermal equilibrium with the atmosphere, the water will always get or remain colder than the atmosphere.
This is due in my opinion to the gravity and relative humidity powered convection of latent heat removed from the water, that always HAS to occur.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#5
Onion Skin Weathering no ice needed in the Namib Desert. Peak summer day time temperatures were usually above 40C.

Will try and work up a summary on lapse rate and heat transfer from my new book. Certainly keeping me quiet. Wink

You might find this interesting.
WHAT SURFACE TEMPERATURE IS YOUR MODEL REALLY PREDICTING?

Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#6
Most desert mornings are frosty? Yes / No.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#7
(04-02-2012, 05:53 AM)Derek Wrote: Most desert mornings are frosty? Yes / No.

Sorry. No. Spent some nine years of my life in deserts and never saw frost. The only time I saw morning dew was on the skeleton coast and that was from moist sea air. Water was always a problem. We drank a case of beer per man per day and didn't put on an ounce. Happy daze. Cool


Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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#8
I think that convection is one of the main sources of heat loss, certainly over land. Due to the poor heat conducting properties of air, conduction will only work very slowly over short distances. Latent heat requires some medium to change physical form. Fine over water, or in a vegetated area but in a dry area such as a desert, mountain top or at the poles convection has to rule the roost.

This is heat transfer by removal or warm air upwards as it expands. It is the principal by which a refrigerator works so I don't see what you have against convection, Derek.
Convection and radiation occur anywhere on the planet all the time, not so latent heat. A desert cools quickly at night! No latent heat involved there.

Radiation is also an important form of heat loss. Once the heat of the ground is converted into radiation then it cannot turn back into heat until it encounters cooler matter with which it can interact (stimulate electron orbitals etc).
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#9
(04-02-2012, 10:16 AM)Climate Realist Wrote: I think that convection is one of the main sources of heat loss, certainly over land.

This is heat transfer by removal or warm air upwards as it expands.

It is the principal by which a refrigerator works so I don't see what you have against convection, Derek.

Is convection heat loss or heat transfer please, you seem to say both.
If heat loss, please explain how, as my pdf tries to explain the heat has already been lost from the object or surface, before convecton occurs.

I thought most fridges use convected then exchanged latent heat to sensible heat?
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#10
Convection occurs when the ground heats a packet of air by conduction and continual rising of the air as it expands. This must be the major form of heat loss from the ground over large parts of the earths surface.

And Derek, it is both heat loss and heat transfer. Heat loss from the ground as it is transferred to the rising and expanding air, which transfers heat to the upper atmosphere as it rises and expands. The ground loses heat and convection transfers the heat to the upper atmosphere.

A fridge works by compressing a gas which due to the pressure increase, gives off heat. This gas is then expanded which then cools and is passed through a heat exchanger inside the fridge to remove heat from the contents. Much in the same way that air expands as it heats, rises, loses heat to the upper atmosphere which then radiates this heat to space, then the air cools, becomes more dense and sinks to the bottom of the atmosphere.

Yes, fridges use phase changes as well and therefore latent heat plays a part, but I think as latent heat is only involved in the case of phase changes (solid to liquid to gas etc), that you have confused yourself somewhat and that as latent heat can only be a factor during phase changes and in the case of the earth where water is present, then convection has to be the major player. Convection and radiation occur everywhere! Convection is the reason why the earths atmosphere stays warm at night, due to the slowness of convection. Latent heat due to changes in the state of water has to be a lesser player.
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#11
(04-02-2012, 03:48 PM)Climate Realist Wrote: Convection occurs when the ground heats a packet of air by conduction and continual rising of the air as it expands.

Ok, so conduction of sensible heat from land to air occurs before and causes convection. One of the points of my pdf.

You do not seem to mention convection of latent heat of water vapourisation?
Where do clouds come from?

With regard to,
Climate Realist Wrote:" Latent heat requires some medium to change physical form. Fine over water, or in a vegetated area but in a dry area such as a desert, mountain top or at the poles convection has to rule the roost. "

Over what percentage of earth's surface can latent heat of water vapourisation not play a significant role?

I would also note phase changes (latent heat) tranports vast amounts of cold down within the climate system too. ie, snow / ice / frost.

From what you describe it would seem to be a very small percentage. Is this a case of the exception proving the rule. Yes / No??

The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#12
"Over what percentage of earth's surface can latent heat of water vapourisation not play a significant role?"

Quite a large area! Deserts, poles, mountain tops, savannah, urban areas. Anywhere where there is less water.

"I would also note phase changes (latent heat) tranports vast amounts of cold down within the climate system too. ie, snow / ice / frost."

You can't transport "cold" as such. Cold is only how our senses let us know an object or environment has less heat than is comfortable for our bodies. Cold in itself does not exist! Only differing amounts of heat in matter.

I'm not saying that evaporation isn't important. Just that you seem to have something against convection. Greenhouses work by stopping convection, thus trapping a warm body of air that would other wise rise. As does a layer of clouds on a winter night in the UK that prevents heat loss by convection and thus prevents frost.

You shouldn't be thinking of "cold" as a physical entity in itself. But of differing levels of heat. At all temperatures above 0K, all bodies have some heat, i.e. some vibrational energy in their molecular structure.

Latent heat is not really heat, neither is radiation. Both have the potential to release energy as heat but that depends on the conditions the latent heat carrying material or the "thermal" (really LW IR) radiation encounters. Think of them as stored heat and not heat in themselves. Whereas, convected air, which I think has been neglected as a source of heat transport in the rush to nail everything on radiation and thus MMGW really is vibrational molecular kinetic enegry, stuff moving, it is heat. Think of the power in a convection thermal. It can keep heavier than air objects aloft. It has enough power to overcome gravity!
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#13
Climate Realist the point of my pdf is that convectin is of latent heat and sensible heat.
What is "anti" convection about that?
Convection is commonly used as if it is a heat loss mechanism, which it is not. It is a positive catalyst to more heat loss by 2 of the actual 3 mechanisms of heat loss at earth's surface.
In that respect, I am anti the present use of convection in many cases, because heat loss and heat transfer, or the transporting of heat, are being confused with each other incorrectly. Namely, first heat loss occurs by sensible heat conduction, or latent heat loss, THEN convection occurs to transport the already lost heat away, which allows more heat to be lost by the two heat loss processes. To say convection is a, or use convection as if it is a, heat loss process is incorrect, that is my main point. Such use misleads, and has been used to downplay the importance of latent heat losses greatly.

Given the world is 71% ocean and most of the remaining is wet and covered in plants, that transpire to keep cool, latent heat losses occur virtually everywhere. Some small examples, as you have given, excepted.

My point is that sensible heat convection is quite weak, latent heat is far, far more powerful. I would also of thought that where latent heat loss is occuriing sensible heat loss is reduced, so latent heat is dominant. Latent heat is why heat pipes work. It is also the basic principle in how a fridge works, whether you describe it as only playing a (implied small) part or not.

Cold IS transported down within the climate system, both sensibly and in change of state, ie snow.
Cold is also the easiest way to think about it because it cools earth's surface.
This enormous part and feature of the climate system is utterly omitted from GH, K&T, AGW.
It is a part that totally destroys all the present explanations / calculations, but heck let us avoid that small issue and talk about calling it less energy.
I think most people can relate to the idea of cold coming down in the system, rain and snow are cold arn't they.

It seems simple explanations to get a point across are not the order of the day...

Richard111 - I stand corrected re onion skin weathering, I have not read anywhere what I think about it.
I do not think it is a constant or single process. It is a combination of thermal stress most diurnal cycles (daily), AND ice frost damage when water is present (intermittent).
I always thought it seemed obvious that the ice / frost damage does most of the work, albeit intermittently, yet, thermal stresses gets all the credit. Which isn't how it ought to be to my mind.
That said it is a bit off topic in my opinion for this thread so I'll leave that subject here on this thread at that point.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#14
No, Derek! "Cold" as such does not exist! There are merely differing degrees of warmth.

I do think you disregard the power of convection, or heat mass transfer as it might be termed as one of the major means oc cooling the planet along with radiation. Your fixation on latent heat does nothing to undermine the Greenhouse theory!

Plus there is another form of heat mass transfer that cools the planet even more effectively than convection that you have totally neglected, and that is the winds that move heat from the tropics to the poles and thus cool the planet, This, I believe is what is the major cause of cooling of the earths surface, essentially weather! And without the winds, latent heat would be even smaller than it is now.

From what basis do you draw your conclusions?? I'm thinking of Nasif Nahle's repeat of the Woods experiment. No latent heat was involved there, yet Nasif prooved that radiation is not trapped in the earths atmosphere and even a small hole on one of his boxes allowed a massive heat loss by convection.

It was actually the prevention of convection in Nasif Nahle's experiments that caused the sealed boxes to heat up so much and the fact they all heated almost identically showed trapped LW IR does not = warming and that greenhouses and indeed the Earth's atmosphere are kept warm by the restriction of kinetic heat mass transfer, i.e. convection and "horizontal convection", i.e. winds moving heat away.
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#15
Climate Realist every single "point" you have put I have already answered, mostly in my piece.
I am afraid it is you who is confused, or can not see the wood for the trees.
This is not the first time you have appeared to take a completely contradictory position with anything I say, seemingly deliberately and because I say it.

I give up with you. You constantly flip or use inappropriately what I suggest. Simply I have better things to do than try banging my head against a brick wall, that is getting you to see any other point of view, let alone consider or understand said point / view, with you.
In short, go and debate with someone else, you are a waste of my time, you are nothing more than a troll to me.
Why, you do it I do not know, I do not do it to you.

Apologies SST, if that is all too much, and I am supposedly out of order, but I genuinely think not.
If that is the end of me here, then so be it.


The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#16
Derek, you have known me on this forum long enough to know I'm not a "Troll". That post of yours is I feel is possibly a little out of order, and certainly incorrect. The P/4 thread you posted previously that you alluded to, I still think is essentially a red herring and different to what the Slayers have said. I'm not having a go at you personally, Derek, and do not mean this to be personal, we are merely having a scientific discussion. Let's keep it impersonal and scientific, not personal and insulting!

Sorry, if you don't like your ideas being discussed. Strong, good ideas would stand up to any examination, so my approach should be welcomed. So I apologise if you have taken my posts as personal, that is not the intention! Accusing me of being a "Troll" doesn't support your position!

I have also not disagreed with you on everything you have said, just on the P/4 and these latent heat issues. The discussion is around facts that I feel are not quite right, not about "having a go at Derek" and "disagreeing with everything he says".

We are having a discussion about the relative importance of latent heat versus convection. I have stated the reasons why I think you have overstated the importance of latent heat and understated the importance of convection. And yes, I have read your articles and I don't think they really address my points.

And I have another few points in support of convection as being the most important, certainly more important than latent heat. Consider this- latent heat only acts to cool the very earths surface where water is present in liquid or solid form and can thus evaporate or sublimate to water vapour. Once in the atmosphere as water vapour, further phase changes can only release heat as vapour goes back to liquid and back to solid. Any expansion would be convection mushc like dry convection but perhaps with a slightly greater heat capacity, depending on the % water vapour. Convection on the other hand operates from the earths surface right up into the high atmosphere, cooling both the earths surface and the layers of the atmosphere.

As for your PDF, some of it is right and some of it is clearly wrong such as this statement:-

"Radiation, conduction and latent heat happen BEFORE convection.
In point of actual FACT conduction and latent heat CAUSE convection"

Part right, part wrong.
As convection occurs in a desert, dry polar regions and the dry air on a mountain top where little or no latent heat transport occurs this is clearly wrong. Yes, conduction from the hot air to the ground provides much of the heat to the air to start convection -agree with you on that- but not necessarily latent heat in a dry area. Sorry Derek, you won't like it but some of your statement is not quite right!

Convection occurs when a packet of air is heated, the air expands due to the extra heat and because the air has expanded it becomes less dense than before and therefore rises. No latent heat needed here, this is why you get convection in the desert. Conduction yes, latent heat not necessarily!

Another point:-

"For our thought experiment, firstly imagine "our" hot cannonball in a vacuum.
1) Radiation losses are very little – Your hand, even if a small distance away (ie a couple of feet), can not feel much at all, especially as the distance the hand is from the cannonball is increased (increasing circumference)".

Not quite true! If the cannon ball were colder than your hand, then yes, I agree you would not feel the radiation as it would not warm your hand, but if the cannon ball is warmer than the hand, then yes, heat transfer will occur and in a vacuum radiation is the only means by which the cannon ball can cool. So radiation loss from the hot cannon ball in a vacuum is not "very little" but is 100% of the heat loss. Yes, the increased distance is due to the inverse square law by which radiation density decreases by distance from a hot object. Agree with you on that one.

It seems to me you have specifically got confused between heat transfer by latent heat, i.e. water evaporating and the water vapour cloud rising and heat transfer by convection, i.e. hot ground conducts and radiates to the cooler air, this air warms, then expands and rises. They are similar, but not quite the same thing as latent heat involves a change of state caused by heat and dry convection is merely the expansion of a gas by heating it. No change of physical state occurs in convection, merely an expansion of the gaseous state.

This statement is also not quite true:-

"Evaporation and vapourisation are often used interchangeably, but are in fact different "terms". Evaporation happens when water boils, but the vapourisation of fluid water can happen at any temperature between 0C and 100C."

Not really, a liquid can evaporate at any temperature that is has a vapour pressure at, and with decreased pressure the evaporation rate increases! Evaporation does not just occur at boilling point! You have actually got the terms the wrong way round as vapourisation can be an instant change from liquid to gas and evaporation of a liquid happens gradually.

Sorry Derek, this is not a personal attack, I'm just trying to help you to understand the science better and correct the errors in the PDFs you publish. It is just if you are going to make statements in a PDF and publish them on a blog then they need to be correct statements backed by good science. And we need to be discussing good science all the time otherwise us Realists will be opening ourselves for attack by the Warmermongerers. We don't need mistakes and misunderstanding, we need correct statements and good science. Science is not personal, it is impersonal and either right or wrong without regard to the beliefs and feelings of those who hold those beliefs. A scientific paper has to get everything right, down to the last details and be very clear.

I don't know what your scientific background is, but I have a degree in chemistry and worked as a chemist for 20 years in industry. It is from this education and experience that I draw my ideas and conclusions.
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#17
(04-05-2012, 05:42 AM)Climate Realist Wrote: Sorry Derek, this is not a personal attack, I'm just trying to help you to understand the science better and correct the errors in the PDFs you publish. It is just if you are going to make statements in a PDF and publish them on a blog then they need to be correct statements backed by good science. And we need to be discussing good science all the time otherwise us Realists will be opening ourselves for attack by the Warmermongerers. We don't need mistakes and misunderstanding, we need correct statements and good science. Science is not personal, it is impersonal and either right or wrong without regard to the beliefs and feelings of those who hold those beliefs. A scientific paper has to get everything right, down to the last details and be very clear.

I don't know what your scientific background is, but I have a degree in chemistry and worked as a chemist for 20 years in industry. It is from this education and experience that I draw my ideas and conclusions.

Fair comments, and a good basis to go forwards from. My apologies to you Climate Realist as I was too quick to react, rather than consider then reply.
" We don't need mistakes and misunderstanding, we need correct statements and good science. " Agreed completely.

Unfortunately I have no scientific training whatsoever academically speaking, I just try my best, as a layman.

I will reply in due course, your reply has given me much insight to the differences between our expressed opinions, and I want to iron them out also.
If I am wrong, and shown to be wrong then so be it. As you say that is not personnal it is just a better understanding of the truth of the matter.

I can not make sense of this comment that I reacted to this morning, in relation to cold brought down within the climate system principally by rain and snow.
" No, Derek! "Cold" as such does not exist! There are merely differing degrees of warmth. "
Surely sensible heat is absorbed / exchanged / transferred, whatever the appropriate term is relatively. Therefore cold in this sense does exist.
My explanation and example therefore also makes sense explained as I did, and your explanation is misleading, as it seems more appropriate for IR rather than sensible heat.

The other point that I will contest more strongly in the near future is that a fridge works by using latent heat, not that latent heat is only a part of how a fridge works, as you have suggested. That to my understanding is a large misrepresentation in your explanation.

" As for your PDF, some of it is right and some of it is clearly wrong such as this statement:-

"Radiation, conduction and latent heat happen BEFORE convection.
In point of actual FACT conduction and latent heat CAUSE convection"

Part right, part wrong.
As convection occurs in a desert, dry polar regions and the dry air on a mountain top where little or no latent heat transport occurs this is clearly wrong. Yes, conduction from the hot air to the ground provides much of the heat to the air to start convection -agree with you on that- but not necessarily latent heat in a dry area. Sorry Derek, you won't like it but some of your statement is not quite right!
"

You are aware that water vapour is lighter than air, so water vapourising does cause convection. It has to.
Conduction causes convection by expanding air, yes, but ALSO latent heat losses just like sensible heat (conduction) losses, also cause convection by making air lighter.
Convection is both of, and created by, conduction AND latent heat losses.

Last week on the Beeb they explained monsoons (THE largest weather event on the planet) without a single mention of latent heat.....
This is an important issue and misdirection, based on the misuse of convection.

As I have recently posted on the latent heat home experiment thread this is really all about heat pipes.
Which are best explained as heat in and heat out (using the convection of latent heat), neccesarily
this has to involve both hot and cold (relatively speaking) of sensible heat, to be understood.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#18
(04-05-2012, 05:42 AM)Climate Realist Wrote: The P/4 thread you posted previously that you alluded to, I still think is essentially a red herring and different to what the Slayers have said.

As people here are aware I was actually party to the discussions within the Slayers of the P/4 issue. I know what was said, and by whom, because I still have the private emails.

The discussions to all intents and purposes ended with a word document titled the battle of the earth models. I am not sure a public version was ever produced, but it should of been.
I will try to remember to email the appropriate person to ask if such a version does or will exist. Given the quote above, it is sorely needed.
If I get hold of such a version of the word document I will post it here.

In essence, there were two schools of thought within the Slayers upon the issue. A majority (against P/4) and an opposing minority (in favour of P/4) view.
Climate Realist is a great fan of Claes Johnson's view point and maths approach, I assume that is what he is referring to when he says what the Slayers say about P/4.
I can assure you that what I wrote in the P/4 thread reflected the majority within the Slayers view on the subject, not the minority view, which is the position Claes Johnson held, and to the best of my knowledge still does hold to.

The above quote I also reacted to, as it does not reflect what I saw actually happen within the Slayers.
I felt it a misrepresentation, from a partly, or not completely informed and biased source.
Climate Realist does not know what went on within the Slayers discussion (that I was actually party to) of the subject, or if he does, it is at best second hand, and seemingly incomplete.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#19
(04-05-2012, 05:42 AM)Climate Realist Wrote: This statement is also not quite true:-

"Evaporation and vapourisation are often used interchangeably, but are in fact different "terms". Evaporation happens when water boils, but the vapourisation of fluid water can happen at any temperature between 0C and 100C."

Not really, a liquid can evaporate at any temperature that is has a vapour pressure at, and with decreased pressure the evaporation rate increases! Evaporation does not just occur at boilling point! You have actually got the terms the wrong way round as vapourisation can be an instant change from liquid to gas and evaporation of a liquid happens gradually.

I quite agree that part is incorrect and badly worded, I had meant to remove it.
I will do so tomorrow, or asap, and reload the pdf without that section.
7th April 2012 - pdf now edited and version in post 1 of this thread is the corrected pdf.
Thank you for pointing it out.

The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#20
(04-05-2012, 05:42 AM)Climate Realist Wrote: We are having a discussion about the relative importance of latent heat versus convection.
And,
(04-05-2012, 05:42 AM)Climate Realist Wrote: Convection occurs when a packet of air is heated, the air expands due to the extra heat and because the air has expanded it becomes less dense than before and therefore rises. No latent heat needed here, this is why you get convection in the desert. Conduction yes, latent heat not necessarily!
And,
(04-05-2012, 05:42 AM)Climate Realist Wrote: It seems to me you have specifically got confused between heat transfer by latent heat, i.e. water evaporating and the water vapour cloud rising and heat transfer by convection, i.e. hot ground conducts and radiates to the cooler air, this air warms, then expands and rises.
They are similar, but not quite the same thing as latent heat involves a change of state caused by heat and dry convection is merely the expansion of a gas by heating it. No change of physical state occurs in convection, merely an expansion of the gaseous state.


I may be reading the above quotes incorrectly, but you appear to me to be saying only conduction causes convection. Am I correct in this interpretation?

Water vapour is lighter than air, molecular weights show this, therefore moist air is lighter than dry air. This is also a cause of convection, possibly a cause that may have eluded many people.

In short, I am saying there is more than one cause (conduction of sensible heat) of convection. Latent heat losses are in fact of greater importance overall as a cause of convection .

I am also suggesting that latent heat losses are a more powerful cause of convection than the conduction of sensible heat. I will use the Fridge for Africa to illustrate this most important point.

Amazing solar-powered fridge invented by British student in a potting shed helps poverty-stricken Africans

Her 'sustainable' fridge works through evaporation and can be used to keep perishable goods such as milk and meat cool for days.

Without using any power, temperatures stay at around 6c.

The fridge comprises two cylinders - one inside the other. The inner cylinder is made from metal but the outer cylinder can be made from anything to hand, including wood and plastic.


[Image: article-1108343-02F9F1BD000005DC-409_468x516.jpg]

Please note point 5 in the above diagram.
Resoaking the material with fresh water will keep the “fridge” working.

This fridge works because of latent heat losses, obviously. But, it also illustrates another point. The fridge is being cooled far more than the surroundings, because it has a damp lining that water evaporates from. If this only occurred by diffusion then the heat losses would be greatly reduced, so there must be convection associated, and because of the water being evaporated. I suggest this shows that the convection caused by evaporation is far more powerful than the convection caused by conduction, otherwise why is the fridge so cool compared to it’s surroundings that are cooled by conduction and convection?

I find it saddening that the Daily Mail newspaper and seemingly every other link I can find on the net referring to this fridge call it a solar powered fridge, when in fact it is clearly a latent heat losses caused by the vapourisation of water and the convection that causes powered fridge.

(04-02-2012, 03:48 PM)Climate Realist Wrote: A fridge works by compressing a gas which due to the pressure increase, gives off heat. This gas is then expanded which then cools and is passed through a heat exchanger inside the fridge to remove heat from the contents. Much in the same way that air expands as it heats, rises, loses heat to the upper atmosphere which then radiates this heat to space, then the air cools, becomes more dense and sinks to the bottom of the atmosphere.

Yes, fridges use phase changes as well and therefore latent heat plays a part, but I think as latent heat is only involved in the case of phase changes (solid to liquid to gas etc), that you have confused yourself somewhat and that as latent heat can only be a factor during phase changes and in the case of the earth where water is present, then convection has to be the major player. Convection and radiation occur everywhere! Convection is the reason why the earths atmosphere stays warm at night, due to the slowness of convection. Latent heat due to changes in the state of water has to be a lesser player.

Being fairly sure of my understanding of how a fridge (and a heat pipe works), I quickly looked this up on the internet, I found the following.
http://www.ior.org.uk/ior_/fantastic_fri...gediag.htm

Please note vapourisation within the fridge removes heat from within the fridge (in heat pipe terms – heat in), and upon (forced) condensation, heat is released at the vent fins (in heat pipe terms – heat out).
All by using the power of latent heat. Latent heat therefore is the operating principle and THE power to cool of a fridge.

Here is another link that also explains how a fridge works, on which I found pages 3 and 5 particularly relevant to this discussion.
http://home.howstuffworks.com/refrigerator.htm


(04-05-2012, 05:42 AM)Climate Realist Wrote: I don't know what your scientific background is, but I have a degree in chemistry and worked as a chemist for 20 years in industry. It is from this education and experience that I draw my ideas and conclusions.

I have said I have no academic, and I will add or formal, scientific training. However, in science that is not a problem, because science is inclusive, not exclusive. How? The scientific method includes EVERYONE, that is it’s purpose. I am permanently grateful to most notably Dr Richard S Courtney, and Luther Haave, because when I helped produce the Cause and Effect paper that Luther and I did together the scientific method was explained as our starting point and method. I will quote from that paper what we wrote in regards of describing the scientific method.

Quote from Cause and Effect paper.
Furthermore, some scientists have become advocates of the hypothesis of enhanced greenhouse effect. Kary Mullis, won the Nobel Prize for Chemistry in 1993, and he writes in his book, Dancing Naked in the Mind Field, of such advocates.
Scientists who speak out strongly about future ecological disaster and promote the notion that humans are responsible for any changes going on are highly suspect.
Turn off the TV. Read your elementary science textbooks.
You need to know what they are up to.
It's every man for himself as usual, and you are on your own.


This paper attempts to aid non-scientists to assess scientific opinions on climate change and to discern the advocates whom Mullis condemns. The assessment requires no scientific knowledge except a basic understanding of the scientific method as explained by Karl Popper ref.17.

Popper argued that all science is based on hypotheses that must be tested to destruction. Sound evidence which does not fit with the hypothesis must logically cause it to be rejected. However, the other side of the same coin is that no hypothesis can ever be said to be proven. Over time, the body of evidence consistent with a successful hypothesis builds up to the extent that it becomes regarded as a theory, for example the theory of General Relativity, or Tectonic Plate theory.

Thomas Kuhn provided a different view of how scientists work18. He introduced the concept of „normal science‟ to cover the situation where scientists work on various topics within a central paradigm. In contrast to Popper, the Kuhnian view is that "wrong" results (i.e. those which are in conflict with the prevailing paradigm) are considered to be due to errors on the part of the researcher rather than findings which damage the consensus view. However, as conflicting evidence increases, a crisis point is reached where a new consensus view is arrived at and this generates a so-called paradigm shift. Simply, Kuhn says scientists are human and have human prejudices.

Advocates of the AGW hypothesis promote Kuhn‟s view and repeatedly cite “consensus” as evidence. Simply, they proclaim that the number of “experts” who hold an opinion is “evidence” that the opinion is correct. But opinions are formed by many things – including personal prejudices – so “consensus” is no help to persons who wish to discern the expert opinions that most closely match physical reality.

Popper‟s philosophy of science is more useful for those who want to decide between competing scientific opinions. According to Popper, the scientific method has the following steps.

1) Observe (preferably empirical data).

2) Explain the observation and or observations (hypothesis).

3) Test the explanation by an experiment (i.e. evaluate a prediction from the hypothesis).
It should be noted that an experiment may consist of looking for information which would confirm or deny the hypothesis, and this is usual in subjects such as climatology and cosmology because climates and stars cannot be altered to conduct a test.

4) Analyze the experimental results and draw a conclusion.

5)
(a) The hypothesis is supported if the experiment confirms the prediction and it may be on its way to being accepted as a scientific theory if others are able to independently duplicate the experimental results.
(b) The hypothesis is rejected if the experiment demonstrates that the prediction was incorrect. In this case it is necessary to return to steps 2), 3) and 4), and this loop is repeated until a hypothesis is obtained which is supported by experimental results.

6) Openly publish the experiment‟s methodology, results and data.
The publication should include discussion and evaluation of all known possible problems and reservations concerning the study it reports.

This method revolutionised human society with the enlightenment. One of its great powers is that it enables non-experts to discern when experts are mistaken. This power was clearly expressed by Thomas Huxley who said;
Science is organized common sense where many a beautiful theory was killed by an ugly fact.
And
The deepest sin of the human mind is to believe things without evidence.

So, when considering the competing claims of scientific experts it is necessary to decide
1. if supporters of one hypothesis have presented an “ugly fact” that defeats an opposing hypothesis, and
2. to ignore the opinions of experts and, instead, to consider the evidence which supports the hypothesis which they present.

Importantly, it should always be kept in mind that all presented hypotheses could be wrong so an “ugly fact” that defeats one understanding of an issue is not evidence that another understanding is correct.

Reference 17
17. Karl R. Popper. The Logic of Scientific Discovery. 1958 English translation.
http://www.questia.com/PM.qst?a=o&d=9219121

End of quote.

I have kept in mind the above quote whilst developing the experiments on the Home experiments to show the power of latent heat thread that I referred and linked to earlier in this thread. It is also why I frequently post, words to the effect, comments / suggestions invited in my posts on numerous threads on this forum. I am trying to be open, I am trying to follow the scientific method.

All that said and hopefully explained clearly and understandably in an open manner, my apologies to all, I am still developing my discussion skills, which are not too hot at present.
Or is that just an expression of the frustrations of all the misrepresentations we have all been fed and have to overcome…
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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