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Old August 6th 15, 06:50 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 2:14:51 PM UTC-4, Alastair wrote:

All solid objects emit radiation based on their temperature. An ideal object which emits a Planckian spectrum is called a black body, but the radiation emitted by non-ideal bodies is often called blackbody radiation too. The term cavity radiation is also used since, a cavity produces the thermodynamic equilibrium which is required for true black-body radiation.

If you place two object at different temperatures side by side with a gap between them, then the hotter object (with a higher temperature) will radiate with a greater intensity than the cooler object (with a lower temperature, since the power they emit is determined by the Stefan-Boltzmann Law J = sT^4, where s is the Stefan Boltzmann constant 5.67 E-8 W / sq m K^4. The cooler object will warm (i.e. its temperature will rise) because it is gaining more radiation than it is losing, and the warmer object will cool because it is emitting more radiation than it is absorbing. This is an example of the First Law of Thermodynamics. Eventually both objects will acquire the temperature of their surroundings, since each of their other five faces will be exchanging heat with that.

Now are you convinced? No, I didn't expect you would be.


========

I'm certainly not. This describes thermal equilibrium and does not even come CLOSE to supporting your hypothesis. In fact, it seems to me to do the opposite.

Stephen.

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Old August 6th 15, 07:03 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 7:14:51 PM UTC+1, Alastair wrote:
On Thursday, August 6, 2015 at 4:19:35 PM UTC+1, RedAcer wrote:
On 06/08/15 15:52, Alastair wrote:
Dawlish,

On Page 576 of University Physics with Modern Physics, Technology
Update, Thirteenth Edition (2010), which continues to set the
benchmark for clarity and rigor combined with effective teaching and
research-based innovation, they write:

"Radiation. Heat transfer by radiation is important in some
surprising places. A premature baby in an incubator can be cooled
dangerously by radiation if the walls of the incubator happened to be
cold, even when the air in the incubator is warm. Some incubators
regulate the temperature measuring the baby's skin ..."

Hot objects radiate heat which warms adjacent objects. Cold objects
radiate cold which cools adjects objects. The latter is difficult to
demonstrate because it is more difficult to maintain a constant cold
temperature than a high temperture. The latter is easy using
electrical heating. However, holding a thermnometer over an object
taken from a freezer will cause the temperature shown to drop.

I hope you will now realise that you are wrong, will apologise and
admit your mistake. Cold radiation does exist.

Cheers, Alastair.


I think you are getting confused with the human feelings of hot and
cold. If you stick with the words 'higher and lower temperatures' and
use well defined objects and laws, viz black-body, black-body radiation
and Stefan-Boltzmann law, then rewrite what you are trying to say and it
may clarify things?


All solid objects emit radiation based on their temperature. An ideal object which emits a Planckian spectrum is called a black body, but the radiation emitted by non-ideal bodies is often called blackbody radiation too. The term cavity radiation is also used since, a cavity produces the thermodynamic equilibrium which is required for true black-body radiation.

If you place two object at different temperatures side by side with a gap between them, then the hotter object (with a higher temperature) will radiate with a greater intensity than the cooler object (with a lower temperature, since the power they emit is determined by the Stefan-Boltzmann Law J = sT^4, where s is the Stefan Boltzmann constant 5.67 E-8 W / sq m K^4. The cooler object will warm (i.e. its temperature will rise) because it is gaining more radiation than it is losing, and the warmer object will cool because it is emitting more radiation than it is absorbing. This is an example of the First Law of Thermodynamics. Eventually both objects will acquire the temperature of their surroundings, since each of their other five faces will be exchanging heat with that.

Now are you convinced? No, I didn't expect you would be. But the clue is in the first sentence of the book that I quoted. "Heat transfer by radiation is important in some SURPRISING places." It may be surprising that cold radiation exists, but that does not stop it being true.


You didn't read what I linked you to did you and you still wish to remain stubbornly ignorant of it.

The first statement in the second law of thermodynamics states that heat flows spontaneously from a hot to a cold body. Always. No exceptions.

Either re-write this and accept the Nobel prize for your efforts, or abandon this idea of cold radiation.

One or the other; there is no in-between. Cold radiation is **impossible**.
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Old August 6th 15, 07:03 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 7:17:56 PM UTC+1, Alastair wrote:
On Thursday, August 6, 2015 at 5:32:08 PM UTC+1, Stephen Davenport wrote:
On Thursday, August 6, 2015 at 10:52:09 AM UTC-4, Alastair wrote:


And of course a thermometer will measure a lower temperature adjacent to an object that is emitting less radiation.


Stephen,

Less radiation is colder radiation. It is being emitted from a colder object.

Cheers, Alastair.


Ridiculous.
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Old August 6th 15, 07:27 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 7:37:06 PM UTC+1, Stephen Davenport wrote:
On Thursday, August 6, 2015 at 2:17:56 PM UTC-4, Alastair wrote:



Stephen,

Less radiation is colder radiation. It is being emitted from a colder object.

========

But with respect that's not COLD radiation!

Stephen.


What is it then? Hot radiation?

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Old August 6th 15, 07:34 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 8:27:10 PM UTC+1, Alastair wrote:
On Thursday, August 6, 2015 at 7:37:06 PM UTC+1, Stephen Davenport wrote:
On Thursday, August 6, 2015 at 2:17:56 PM UTC-4, Alastair wrote:



Stephen,

Less radiation is colder radiation. It is being emitted from a colder object.

========

But with respect that's not COLD radiation!

Stephen.


What is it then? Hot radiation?


Please go and learn about this. You are making yourself look silly.

No-one supports you and it would take an idiot to do so, because your premise is ridiculous.


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Old August 6th 15, 07:38 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 7:43:19 PM UTC+1, Bernard Burton wrote:

Yes, Stephen is correct. All objects above absolute zero are emitting
radiation. A thermometer in a medium at constant temperature will only read
a constant value if the amount of radiation it is emitting is exactly
balanced by that it is receiving from its surroundings, e.g. it is in
radiative equilibrium. The amount of radiation emitted by the surroundings
will depend on their temperature. If a portion of the surroundings at a
given temperature is replaced by one at a lower temperature, the amount of
radiation received by the thermometer will fall, and the indicated
temperature of the thermometer will fall until the radiation emitted by the
thermometer matches the new value coming from its surroundings, and it
regains radiative equilibrium.


Bernard,

That is just what I am saying! If you put an object in a cold store its temperature will fall to that of its environment. That is because the temperature at which the radiation is emitted from the walls is colder than the object you have just introduced. Or if you put a baby in an incubator with cold walls the same thing happens.

"Uncle Jim taught me that if everyone thinks your idea is nuts, it just might be a stroke of genius." Richard Branson, Founder at Virgin Group
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Old August 6th 15, 08:17 PM posted to uk.sci.weather
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Default Cold Radiation

You really, really don't understand this do you? Please research it. Many universities offer a pre-undergrad physics course online, free and gratis. You would do well to undertake such a course.
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Old August 6th 15, 08:24 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 3:38:20 PM UTC-4, Alastair wrote:

"Uncle Jim taught me that if everyone thinks your idea is nuts, it just might be a stroke of genius." Richard Branson, Founder at Virgin Group


=========

And it might just be nuts.

I hate the Galileo Gambit.

Stephen.
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Old August 6th 15, 08:50 PM posted to uk.sci.weather
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Default Cold Radiation

On Thursday, August 6, 2015 at 3:52:09 PM UTC+1, Alastair wrote:
Dawlish,

On Page 576 of University Physics with Modern Physics, Technology Update, Thirteenth Edition (2010), which continues to set the benchmark for clarity and rigor combined with effective teaching and research-based innovation, they write:

"Radiation. Heat transfer by radiation is important in some surprising places. A premature baby in an incubator can be cooled dangerously by radiation if the walls of the incubator happened to be cold, even when the air in the incubator is warm. Some incubators regulate the temperature measuring the baby's skin ..."

Hot objects radiate heat which warms adjacent objects. Cold objects radiate cold which cools adjects objects. The latter is difficult to demonstrate because it is more difficult to maintain a constant cold temperature than a high temperture. The latter is easy using electrical heating. However, holding a thermnometer over an object taken from a freezer will cause the temperature shown to drop.

I hope you will now realise that you are wrong, will apologise and admit your mistake. Cold radiation does exist.

Cheers, Alastair.


Is this not like saying there is dark radiation that makes bright objects darker? Surley cold is just lack of heat or am I missing something?


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