On Saturday, August 8, 2015 at 9:56:39 AM UTC+1, Martin Brown wrote:

*Everything* radiates thermal energy according to Plank's law usually
approximating a black body according to its temperature.

https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Stefan...3Boltzmann_law

Energy *transfer* between bodies varies according to the difference
between the fourth power of their absolute temperatures. Net energy flow
always being from the hotter to the cooler body.

The Earth's temperature ~290K is determined by being in thermal
equilibrium with one sun at 5500K subtending an angle of 0.01 radians
and ~4pi of empty space radiating at 4K (the microwave background).

Earth gains energy from the sun and thermalises it and loses energy to
the sky but nowhere is there any "cold radiation".

What about the microwave background at 4K. Can't we call it cold radiation?

Everything radiates thermal radiation to everything else in an amount
determined by its absolute temperature and surface emissivity.

However, holding a thermometer over an object taken from a freezer
will cause the temperature shown to drop.

Yes. Because the cold object below the thermometer is no longer
radiating at the same temperature as the rest of the surroundings. It is
the thermometer that is on average donating heat radiation to the cold
block which is not being returned any more in sufficient amount to
maintain its temperature.

Well, can't argue with what I haven't snipped.

But the reason the temperature on the thermometer drops is because the absorbed "cold" radiation is less than that which is emitted. The emissions are unchanged. It is the absorption from the cold radiation that causes the temperature to fall.

Just try to see why I am correct rather than searching for flaws.

Cheers, Alastair.

On Saturday, August 8, 2015 at 7:26:34 AM UTC-4, Alastair wrote:

However, if he had replaced the bulbs in the lamp posts with his bulbs, then the street would have been darker, just as if you shine cold radiation on an object it becomes colder.

Professor Darklight never carried out his experiment but Professor Pictet did. And he got the results I have described.

==============

I will jump on for one more go around. I have looked at the link you provided earlier to that experiment, and thank you for that. However, the intervening 300 years have provided ample time for Pictet's experiment to be examined. I will refer you to this link, for example:

http://www2.ups.edu/physics/faculty/evans/Pictet's%20experiment.pdf

I quote a pertinent passage here (and pay close attention to the final paragraph):

"Let us note that every object - even a cold object - con*tinually emits radiation. Each object also continually receives radiation that has been emitted by the objects sur*rounding it. The energy emitted per unit time by a given object depends both upon the object's temperature and the properties of its surface. A highly polished metal mirror is a very poor absorber of infrared radiation; it is also, consequently, a poor radiator. Thus we may safely ignore any emission or absorption of radiant heat by the mirrors them*selves. The sole function of the mirrors then consists in the reflection of the radiation that is incident upon them.

Consider first the version of the experiment involving a flask of boiling water. This flask emits radiation in all direc*tions. A negligible part of this radiation is received directly by the air thermometer, which has but a small cross-sectional area and which is placed at a considerable distance from the flask. [In Fig. 5(b)] we imagine the mirrors to be placed so that the focus of mirror A lies in the flask, and the focus of B in the bulb of the thermometer. Now we direct our attention toward that part of the radiation from the flask which happens to strike mirror A.

This radiation will, after two reflections, impinge on the bulb of the thermometer. This is radiation that the thermometer did not receive prior to the introduction of the mirrors. Of course, the thermometer also receives radiation from other objects in the room. The introduction of mirror B effectively eliminates the right third or half of the room as a source of radiation for the thermometer. The effect of the mirrors is therefore to replace a part of the ambient radiation that formerly impinged on the thermometer by the more intense radiation from the flask. The thermometer therefore grows a little warmer.

The version of the experiment involving a flask of snow may be explained in a similar way. Before the mirrors are introduced, the air thermometer receives radiation from all the objects in the room surrounding it. After the introduction of the mirrors, the radiation from the right third or half of the room is cut off from the thermometer by mirror B. This relatively high-temperature radiation is replaced by the radiation from the flask of snow. The thermometer now receives less energy per unit time than previously. The thermometer, initially at room temperature, now radiates away more energy than it absorbs, and so suffers a decrease in temperature."

From: "Pictet's experiment: The apparent radiation and reflection of cold"
James Evans, Department of Physics, University of Puget Sound, Tacoma, Washington 98416
Brian Popp, Department of Physics FM-15, University of Washington, Seattle, Washington 98195


Stephen.

On Saturday, August 8, 2015 at 1:10:13 PM UTC+1, Alastair wrote:
On Saturday, August 8, 2015 at 10:14:21 AM UTC+1, Len Wood wrote:
On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

No, in that case, I am calling the absorbed radiation cold radiation. The net radiation is the emitted less the absorbed. Hence the object will cool..

Yes, but it doesn't cool other things!


On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.

It cools because the absorbed radiation is colder than that which it is emitting.

Utter rubbish

During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

It is just radiation, most from the sun, but some re-radiated from other surfaces.

A better name for solar radiation would be hot radiation rather than warm.. If you call it warm then I should call my cold radiation cool.

Rubbish. It is just radiation. As you've been told by several people, every body whose temperature is above absolute zero will emit electromagnetic radiation. It doesn't cool anything, though. That's where your ideas become ridiculous.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.

Agreed, but if you call the radiation emitted by cold bodies cold radiation then it makes sense to say that it will cool a warmer body which absorbs it.

In science it is important to understand the energy balance at the surface in question.

I fully understand energy balance, but a radiation balance requires an input and an output. I am saying if the input is less than the output then the input is cold radiation.

Utter tripe - and this is why no-one is agreeing with you and why you are making a fool of yourself by simply not learning from those trying hard to explain this to you.


I hope this helps.

It will, if my response causes you to ask yourself whether I am correct, and not where I am going wrong.

You are completely wrong and your ideas violate the second law of thermodynamics, which you do not understand. Why on earth should a response make someone ask whether you are right?

Putting it another way, if you call the radiation emitted by a cold body "cold radiation" then any warm body (i.e. at a higher temperature than our cold body) will cool when it absorbed the cold radiation. It does not need to be called cold radiation for this to happen. If you call it cool radiation the warm body will still cool when it absorbs that radiation. In fact you could give it any name, e.g. Darklight, but the effect would be the same. The warmer body would cool because its net radiation would be negative.

Hilarious. I'd rather you just learned the physics and accepted your silly mistake, but if you don't, it is fun watching you respond to absolute sense from many people by spouting unscientific garbage, because you are ignorant of the physics.


Cheers, Alastair.

Stephen.

Alastair referenced exactly the same discredited experiment last time he tried to persuade someone that 'cold radiation' exists. I referenced a very similar explanation of why the explanations offered by the experiment is not valid. Alastair failed to learn then and Is abjectly failing to learn now.

Paul

On Saturday, August 8, 2015 at 1:10:51 PM UTC+1, Dawlish wrote:
On Saturday, August 8, 2015 at 12:26:34 PM UTC+1, Alastair wrote:
I learnt my Kinematics at University while studying for an engineering degree,

There, apparently, you learned this:

'if you shine cold radiation on an object it becomes colder'.

I'm sure it wasn't your teachers, it would have been you simply not understanding basic thermodynamics.

Just hilarious to watch you here, Alastair. It really is bsolutely hilarious.

How about just answering the questions.

On Saturday, August 8, 2015 at 1:55:21 PM UTC+1, Dawlish wrote:
On Saturday, August 8, 2015 at 1:10:13 PM UTC+1, Alastair wrote:
On Saturday, August 8, 2015 at 10:14:21 AM UTC+1, Len Wood wrote:
On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

No, in that case, I am calling the absorbed radiation cold radiation. The net radiation is the emitted less the absorbed. Hence the object will cool.

Yes, but it doesn't cool other things!


On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.

It cools because the absorbed radiation is colder than that which it is emitting.

Utter rubbish

During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

It is just radiation, most from the sun, but some re-radiated from other surfaces.

A better name for solar radiation would be hot radiation rather than warm. If you call it warm then I should call my cold radiation cool.

Rubbish. It is just radiation. As you've been told by several people, every body whose temperature is above absolute zero will emit electromagnetic radiation. It doesn't cool anything, though. That's where your ideas become ridiculous.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.

Agreed, but if you call the radiation emitted by cold bodies cold radiation then it makes sense to say that it will cool a warmer body which absorbs it.

In science it is important to understand the energy balance at the surface in question.

I fully understand energy balance, but a radiation balance requires an input and an output. I am saying if the input is less than the output then the input is cold radiation.

Utter tripe - and this is why no-one is agreeing with you and why you are making a fool of yourself by simply not learning from those trying hard to explain this to you.


I hope this helps.

It will, if my response causes you to ask yourself whether I am correct, and not where I am going wrong.

You are completely wrong and your ideas violate the second law of thermodynamics, which you do not understand. Why on earth should a response make someone ask whether you are right?

Putting it another way, if you call the radiation emitted by a cold body "cold radiation" then any warm body (i.e. at a higher temperature than our cold body) will cool when it absorbed the cold radiation. It does not need to be called cold radiation for this to happen. If you call it cool radiation the warm body will still cool when it absorbs that radiation. In fact you could give it any name, e.g. Darklight, but the effect would be the same. The warmer body would cool because its net radiation would be negative.

Hilarious. I'd rather you just learned the physics and accepted your silly mistake, but if you don't, it is fun watching you respond to absolute sense from many people by spouting unscientific garbage, because you are ignorant of the physics.


Cheers, Alastair.

What is the answer to those 4 questions?

On Saturday, August 8, 2015 at 3:03:26 PM UTC+1, Alastair wrote:
On Saturday, August 8, 2015 at 1:55:21 PM UTC+1, Dawlish wrote:
On Saturday, August 8, 2015 at 1:10:13 PM UTC+1, Alastair wrote:
On Saturday, August 8, 2015 at 10:14:21 AM UTC+1, Len Wood wrote:
On Saturday, 8 August 2015 00:25:04 UTC+1,

Alastair,
It is net cooling by radiation you are talking about, as some on this thread have hinted.
You can call it cold radiation if you like, but that is not very scientific despite you finding it at odd places in the literature.

No, in that case, I am calling the absorbed radiation cold radiation. The net radiation is the emitted less the absorbed. Hence the object will cool.

Yes, but it doesn't cool other things!


On a clear calm night a land surface cools by radiation.
It loses more heat than it absorbs. Presumably you are calling this cold radiation.

It cools because the absorbed radiation is colder than that which it is emitting.

Utter rubbish

During a sunny day a land surface warms by radiation. Presumably you want to call this warm radiation.

It is just radiation, most from the sun, but some re-radiated from other surfaces.

A better name for solar radiation would be hot radiation rather than warm. If you call it warm then I should call my cold radiation cool.

Rubbish. It is just radiation. As you've been told by several people, every body whose temperature is above absolute zero will emit electromagnetic radiation. It doesn't cool anything, though. That's where your ideas become ridiculous.

Cold bodies radiate, but your body only feels cold because you are radiating more heat than you are absorbing from the cold body. Net cooling by radiation again.
There is no real need to talk about warm or cold radiation.

Agreed, but if you call the radiation emitted by cold bodies cold radiation then it makes sense to say that it will cool a warmer body which absorbs it.

In science it is important to understand the energy balance at the surface in question.

I fully understand energy balance, but a radiation balance requires an input and an output. I am saying if the input is less than the output then the input is cold radiation.

Utter tripe - and this is why no-one is agreeing with you and why you are making a fool of yourself by simply not learning from those trying hard to explain this to you.


I hope this helps.

It will, if my response causes you to ask yourself whether I am correct, and not where I am going wrong.

You are completely wrong and your ideas violate the second law of thermodynamics, which you do not understand. Why on earth should a response make someone ask whether you are right?

Putting it another way, if you call the radiation emitted by a cold body "cold radiation" then any warm body (i.e. at a higher temperature than our cold body) will cool when it absorbed the cold radiation. It does not need to be called cold radiation for this to happen. If you call it cool radiation the warm body will still cool when it absorbs that radiation. In fact you could give it any name, e.g. Darklight, but the effect would be the same. The warmer body would cool because its net radiation would be negative..

Hilarious. I'd rather you just learned the physics and accepted your silly mistake, but if you don't, it is fun watching you respond to absolute sense from many people by spouting unscientific garbage, because you are ignorant of the physics.


Cheers, Alastair.

What is the answer to those 4 questions?

What 4 questions - for the second time. I'll be happy to answer, but repeating 'answer the questions' isn't actually getting you anywhere.

On Sat, 8 Aug 2015 04:26:33 -0700 (PDT)
Alastair wrote:

I learnt my Kinematics at University while studying for an
engineering degree, not from some smart alec teacher.

I cannot believe that any qualified teacher or university professor
would be daft enough to teach that centrifugal force is real.

Yours wasn't
Dawlish by an chance? OK the centrifugal force is not a force field
like gravity, magnetism, etc., but the centrifugal force can be
calculated, see your link which describe it
http://scienceworld.wolfram.com/phys...ugalForce.html . That
link is proof enough for me. Strange that one can get so many hits
for centrifugal force if it does not exist.

You can get many hits for chemtrails but that doesn't make them any
more real than centrifugal force.


By the way, if you do release the centripetal force, e.g. a hammer at
the Olympics games, then it will fly off, just as you predict if the
centrifugal force did exist.

The hammer flies off because the force is removed, there is no need to
invent another force to explain it.


--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

On Sat, 8 Aug 2015 05:30:42 -0700 (PDT)
Alastair wrote:

What about the microwave background at 4K. Can't we call it cold
radiation?

No, because it's warmer than 0K.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

On Sat, 8 Aug 2015 04:26:33 -0700 (PDT)
Alastair wrote:

As far as your fictitious Professor Darklight is concerned I am quite
willing to disbelieve in his existence, or that his dark lights would
have worked. However, if he had replaced the bulbs in the lamp posts
with his bulbs, then the street would have been darker, just as if
you shine cold radiation on an object it becomes colder.

The street would have been darker through the removal of the original
bulbs, not through any transmission of "dark light". In the same way
that Cloddy failed to realised that you cannot radiate a beam of
darkness, it is impossible to radiate a beam of "coldth".

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/