... this topic has been bugging me all weekend.
The source of my ire is statements like this:
"Certain gases in the atmosphere are transparent to the incoming short-wave solar radiation but trap (absorb) the outgoing long-wave terrestrial radiation. This increases the kinetic energy of the gas molecules causing the temperature of the atmosphere, and subsequently the Earth’s surface, to rise.
Most absorption of infrared radiation takes place in the lower atmosphere, the troposphere. This warming phenomenon (33C) is known as the natural greenhouse effect..."
Nobody disputes that the average surface temperature at the surface is 33C higher than it 'should' be. But it is quite simply untrue, and few people are daft enough to claim, that the whole atmosphere is 33C warmer than it 'should' be.
I find it cathartic if I write things down on this blog. So here we go again (hopefully for the last time)...
As always, first write down what you know and what most people agree on (or can easily Google for themselves, which I why I haven't bothered putting in many links).
1. Earth's gravity pulls everything, including air, down. It must do, or else it all would just float off (as do some very light atoms).
2. For a given temperature, the more molecules (most of the atmosphere is molecules, let's ignore the few atoms) there are per unit volume, the higher the pressure. Atmospheric pressure at sea level is whatever it is, defined as 760.00 mmHg; 1013.25 mbar; or 101.325 kPa. Those are just units.
3. Every gas molecule is:
a) pulled *down* by gravity, and
b) pushed *up* by the 'net pressure difference' - the air just below any molecule is at slightly higher pressure than the air just above it, the net difference pushes upwards.
In an equilibrium situation (calm, still night), the down and up forces cancel out. The force of Earth's gravity falls slightly as you move away from Earth, but for these purposes, it's constant at all altitudes. The 'net pressure difference' must therefore be equal and opposite to gravity at all altitudes, and so the pressure falls at a constant rate as you go up.
From Wiki: "In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation."
4. Let's not worry about the subtle differences between conduction, convection and radiation. Gas molecules are so close together as makes no difference. In practice, the biggest movements are winds, which usually go horizontally, not up and down. But for the sake of this explanation, let's assume a calm, still night.
5. The main source of heat for the Earth's surface and atmosphere is the Sun. It heats by day and things cool down at night. In the absence of an atmosphere, the average temperature on Earth would be the same as on our Moon i.e. 255K. The atmosphere increases that by 33C/K to 288K.
6. Air pressure falls steadily as you go up (from 3.) and so temperature falls steadily too. This is hardly surprising. Temperature is just a measure of "how often atoms or molecules bump into each other". (this is a simplification but is acceptable for practical purposes). Pressure = denser = more molecules per unit volume = more collisions = warmer; lower pressures = thinner = fewer molecules = fewer collisions = cooler.
7. The molecules at the surface can't dissipate heat by rising (as some people argue), they are only warm because of where they are. The pressure/heat some think should cause them to rise is equal and opposite to the pressure from the air above pushing them down and gravity pulling them down. You might as well ask, why don't the colder molecules fall down. They are being held up by air pressure from below. Of course there is no physical barrier, and lots of molecules do swap places vertically, but , so what? The equilibrium is unchanged. As I said, in this explanation, it is a calm, still night.
------------------------------
Going by the comments, some people really struggle with para's 6. and 7. I refer them to para 14. for an example to help understanding.
------------------------------
8. If you are clever enough, you can calculate the rate at which temperature and pressure fall with height. Those, and the relationship between them are derived from other constants and equations.
9. In practice, assuming average humidity, temperature falls/increases by 6.5K for every km you go up/down in the lowest 11 km of the atmosphere (aka the moist adiabatic lapse rate). And pressure falls/increases by about 12% for each km you go up/down (up to a max at sea level, ignoring the few places below it). These rates get smaller and smaller as you go up towards and past 11 km, but that need not concern us down here on the surface and where the actual weather happens.
10. Note - the height of 11 km and the lapse rates I'm using are averages. Over the Poles, the atmosphere is thinner and the lapse rates are higher; over the Equator, the atmosphere is thicker and the lapse rates are lower.
11. Let's bring that 255K expected temperature (from 5. above) back in to the proceedings. There's a certain amount of air in the atmosphere. If you start at sea level, 288K and deduct 6.5K for every km you go up, and you go up until half of the air is beneath you and the air pressure is half what it is at sea level i.e. up 5.5 km, the temperature is 288K minus (5.5km x 6.5K/km) which is pretty close to 255K. In other words, the overall average temperature of the atmosphere is +/- 255K
12. Unsurprisingly, above that height, pressure and hence temperature keep falling, all the way down close to zero pressure and to 217K (-57C), where they start to flatten off (and need not concern us). The bottom half (zero - 5.5km) is warmer than you are supposed to expect (255K) ... and the top half (5.5km and upwards) is colder than what you are supposed to expect (255K). All that heat that should be up there is simply in the lower half.
13. So far this has all been non-contentious, consensus stuff I hope. Here's the contentious bit - mainstream global warming theory gives various alternative explanations why it's warmer than expected at the surface. But it does not explain
a) where all the Gravity Thermal Effect went, or why it is nonsense;
b) why it's colder than expected higher up.
If the surface were 33C warmer than expected and the top of Mount Everest were at least a tiny bit warmer than expected, or at least, no cooler than expected, fair enough. But it's not. It's a damn' sight colder than expected.
14. To help visualisation para's 6. and 7. - imagine a Slinky spring with regularly spaced coils. You fix one end to the table and pull up the other end. The coils will now be closer together at the bottom and further apart at the top.
Now imagine that there is a bead attached to each coil directly above the one beneath. They started off evenly spaced, but once the spring has been stretched, the lower ones are closer together and the higher ones are further apart. These beads are our molecules. You simulate the movement of molecules in the gas by jiggling the top of the spring randomly - short jerks, long jerks; fast jerks, slow jerks; short time intervals; long time intervals; up/down and sideways etc.
If you count the number of times that each bead bumps into another bead (or the bottom bead hits the table), the lower down a bead is, the more collisions it will experience. Number of collisions is how we measure temperature, so the lowest beads are the warmest and each the upper beads are the coolest.
15. That's the same as the distribution of molecules in the atmosphere. The apparent temperature difference is merely a result of them being squashed together at the surface and pulled apart at the top, see 6. above. Which is why it's so cold at the top of Mount Everest, even on a sunny, still day.
16. So we can rephrase the original statement thusly:
"The presence of the atmosphere and the effect that gravity has on its density cause the Earth’s surface temperature to be +/- 33C warmer than it would be in the absence of an atmosphere. It is conjectured by some that gases such as CO2 or CH4 might increase this effect, but the amount of warming they cause is difficult to establish."
Sunday, 8 March 2020
OK, one last attempt at summarising the Gravity Thermal Effect...
Subscribe to:
Post Comments (Atom)
53 comments:
The Alarmists want to make it simple for mass consumption: Green is good, CO2 is bad, the science is settled, renewable energy companies are on the side of the angels, oil companies are on the side of the devil, you too can help save the world if you use a bamboo toothbrush etc etc ad nauseam. However what I think you have manged to prove is that the mechanisms involved are anything but simple and we don't yet understand them fully even now, probably because nobody is being paid to look into the matter. The funders are nearly all alarmists and the oil companies don't care. They know people only buy their products because they have to, they don't need to persuade anyone with science, or at least not that kind of science.
B, thanks, but the mechanism I described IS simple. It's GSCE level physics that the teacher could run through in ten minutes, just to pull together all the other general topics already covered anyway. The fact they don't is very worrying.
People are still free to move on, decide their physics teacher was talking rubbish and decide that a vague and contradictory set of alarmist ideas better explain why it's so cold up Mount Everest.
Wouldn't the atmosphere nearer to ground level respond to warming by expanding/rising?
S, see para 7.
S, and para 14. Why are the coils no longer evenly spaced?
It's just that some warmists say the the extra heat is causing the seawater to expand. I defer to you on the science.
S, woah there! I'm discussing explanations, not outcomes.
Thank you for this post which is very interesting. Can I just ask for clarification of 7. "The molecules at the surface can't rise to dissipate heat"
I understand that this correct if all areas of land are receiving incoming heat at the same rate, but they are not at a local level (birds on thermal updrafts and Cumulonimbus) or global level (trade winds and the jet stream come from hot equatorial air rising at the fat part of earth at a faster relative speed, and then falling back down on the cooler thinner parts of earth)
Temperature is not the aggregate Kinetic energy of group of molecules. It is the average kinetic energy of the single molecules in the group. More molecules in fixed a volume of space is not a temperature rise for that volume of space.
Maybe what you have in mind is the "Thermal Energy" of a group of molecules.
Besides you seem to be describing a distribution of temperature, or otherwise thermal energy, rather than a cause. The denser air would have more thermal energy, but that would not be measured by a thermometer as a thermometer measures the kinetic energy of the molecules that it is in contact with.
OTOH. See caveat. winds redistribute mainly horizontally.
Din, you are now arguing with undisputed and observable FACTS. Why?
"The Hadley cell, named after George Hadley, is a global scale tropical atmospheric circulation that features air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth's surface, descending in the subtropics, and then returning equatorward near the surface"
10km up is not horizontal.
It is not an undisputed and observable fact that temperature difference is caused by more molecules being in a given space , that, is explicitly not the case.
OTOH, true, but that has nothing to do with the explanation.
Din, it is indisputable that air at ground level is denser (higher pressure) and warmer than air higher up. I'm not sure what level of reality you are operating on.
Correlation is not causation.
You need a mechanism.
The kinetic energy of a gas molecule is not increased by proximity to other molecules. If you do want a temperature increase at ground level due to gravity you need to increase the kinetic energy of air molecules at ground level, such as a dynamic pumping effect from the molecules above due to pressure cycles, or molecules speeding up as they fall.
Din "You need a mechanism... such as a deynamic pumping effect from the molecules above"
That is exactly the mechanism, and that is exactly how I explained it. Even on a still night, molecules are whizzing around and bumping into each other.
"Can I just ask for clarification of 7. "The molecules at the surface can't rise to dissipate heat"
Perhaps it would be better to replace "can't" with "largely, don't". I am not sure if Mark's explanation as to why is correct, but that is what we observe.
"3. Every gas molecule is:
a) pulled down by gravity, and
b) pushed up by the net difference in pressure between the layer immediately below it and the layer immediately above it."
a) is correct, b), AFAIK, isn't. Every gas molecule is free to move throughout the atmosphere. To a certain extent, less dense gas molecules rise through the atmosphere due to displacement and more dense ones fall. However this process is not absolute, because otherwise there would be no helium in the atmosphere at ground level and there is. So at a low enough concentration, lighter gas molecules are "dissolved" in the heavier ones. Why don't all the heavier molecules sink down to the surface then? The answer is, AFAICR from my A level physics, that gas molecules are mutually repellent, like commuters on a tube train. When the passenger density is low, passengers stand or sit far apart, but the more passengers get on, the closer they move together. The same happens in the atmosphere. Each molecule is trying to space itself as far as it can from every other molecule. The more molecules there are above it, all being pulled down by gravity, the less far it can keep itself from the other molecules. You can't call this force "pressure" because pressure is force over an area and the area of each molecule is so small as to be negligible, making any pressures too large to be meaningful.
"Temperature is just a measure of "how often atoms or molecules bump into each other"."
AFAIK, temperature is a measure of how fast the molecules are moving, not how often they bump into each other. OK they might bump into each other more if they are moving faster, but that's just a side effect. "Bumping" is not a recognised form of energy, whereas speed is (kinetic). However, the temperature of anything depends on how much energy it contains: obviously a cubic metre of air containing 10^24 molecules will be warmer than a cubic metre of air containing 10^23 molecules, all other variables being the same and all molecules having the same energy.
"7. The molecules at the surface can't rise to dissipate heat (as some people argue), they are only warm because of where they are. "
This conflating two effects. The air (not the molecules, they don't really have heat, they have speed) is at a certain temperature at a certain height because of its mass density and hence its heat density. If extra heat is added, the air expands and therefore its density changes, therefore it becomes bouyant. Unless it cools down then it should continue to rise because although it expands as it rises, its specific heat is always greater then the air around it.
"5. The main source of heat for the Earth's surface and atmosphere is the Sun. It heats by day and things cool down at night. In the absence of an atmosphere, the average temperature on Earth would be the same as on our Moon i.e. 255K. The atmosphere increases that by 33C/K to 288K."
The Moon has gravity, therefore it must have an atmosphere, albeit a thin one. Presumably we can calculate what the Earth's surface temperature would average during the day, but in the night, it would fall to the temperature of space, whatever that is. There is no reason to suppose the average temp over 24 hours would be the same as the Moon. However, the 288K figure is easily arrived at by observation, so there is no reason to suppose it to be inaccurate, nor the 217K figure for "space". Nor is there any reason to doubt the moist adiabatic lapse rate figure or the actual recorded temperature at the top of Mt Everest. All of which leaves us with one figure, the only one not derived from direct observation, which is the 33K difference caused by the presence of the atmosphere as the one that questionable.
B, re 3(b). I lifted this point from a Feynman lecture published by some American university. So go and argue with them if you think it's wrong. And yes of course there is mixing, this is GCSE level stuff not a complete model of the universe.
I have looked up that very point and inserted a link in para 6 to an article which says that the number of collisions is not strictly how heat is generated. But it is exactly how heat is measured - the number of times a molecule bumps into the thermometer. So this will do for our purposes.
Re 7. It's not conflating two effects. They are two sides of the same coin; they are in balance. Each influences the other, it doesn't matter which you start with to explain or predict the other. And can we stop going on about "extra heat being added". I point out several times that I am looking at an equilibrium situation, a calm, still night.
"B, thanks, but the mechanism I described IS simple."
It is, but it doesn't, for instance, explain why the solar heating from the surface isn't carried back into space by convection.
"If the surface were 33C warmer than expected and the top of Mount Everest were at least a tiny bit warmer than expected, or at least, no cooler than expected, fair enough. But it's not. It's a damn' sight colder than expected."
Why are we expecting the Earth to be 255K in the absence of an atmosphere? If the theory doesn't fit the facts, discard the theory. (unless you are an Alarmist, in which case you ignore, or try to rubbish the facts). So the top of Mt Everest is colder than expected under this theory must mean the theory is wrong and the Earth is not 33K warmer because of the presence of its atmosphere. Either there is another mechanism in operation or the 33K figure is wrong. Since I would have thought that the 33K figure would have been challenged by now if it was wrong (but who knows, we are dealing with people who have Belief), I suspect that the answer is the former, i.e. it is not as simple as the Alarmists would like to make out.
Mark,
You need to make that 'calm,still night' statement much more obvious. In effect you are looking at a purely theoretical ideal set of conditions.
A lot of the comments are based on a non-equilibrium situation.
>Bayard you comment is wrong
" the temperature of anything depends on how much energy it contains: obviously a cubic metre of air containing 10^24 molecules will be warmer than a cubic metre of air containing 10^23 molecules, all other variables being the same and all molecules having the same energy."
That is the thermal energy content not the temperature.
If it was the temperature then a cylinder of compressed air sitting in a room would be hotter than the surrounding air in the room. And a cylinder of compressed air is not hotter.
> Mark
"molecules are whizzing around and bumping into each other."
yes and continue then , what does that have to do with Gravity.
B, "All of which leaves us with one figure, the only one not derived from direct observation, which is the 33K difference caused by the presence of the atmosphere as the one that questionable."
Well, you prove that the figure is wrong, then you do a post explaining why it gets colder as you go higher up.
VFTS, thanks, but it's not "a purely theoretical ideal set of conditions". It is the overall average of all conditions, extreme in either way and normal. All the figures are averages, lapse rates can be lower or higher. There are temperature inversions, winds, whatever.
Din, "yes and continue then, what does that have to do with Gravity".
I refer you, once again to the actual post, para 1, 3, 6, 7, 9 and 14. Try reading them?
This is ALL down to gravity. Without gravity we wouldn't even have an atmosphere, or even a planet, or stars, or pretty much anything.
@ all of you, I'm relieved to see that nobody has pointed out any actual logical or mathematical errors or offered a better explanation, even if that is just falling back on Warmenism (where's PaulC156?).
Therefore, for the time being, this summary will serve as the Most Likely Explanation.
B, "It is, but it doesn't, for instance, explain why the solar heating from the surface isn't carried back into space by convection"
No it doesn't. It doesn't explain why iron rusts, or why eggs go solid when you boil them either. It explains why it's warmer at sea level and cooler on Mount Everest.
What is "all down to gravity" . You have not even stated what you are thinking of describing.
It is ridiculous this dialogue has bee going on for two weeks and the forum discussion has not even settled on what the word temperature refers to.
Din, the post title explains what I am describing.
I don't care for smart arse definitions of what temperature is. It is sufficient to know how it is measured.
Other than, after reading the post and all those comments, my brain exploding this is fascinating as the arguments prove that 'the science is NOT settled'. In any event 'science' is never 'settled'. That's the point of science. It's the constant search for truth.
paras 6 14 and 15 are not correct. The rate of collisions is not how we measure temperature.
Once there are enough collisions with the thermometer occurring for the thermometer and gas to be in equilibrium then for a greater rate of collisions no further heating of the thermometer occurs and the thermometer gives the correct reading of the gas temperature.
That is demonstrated by the fact that the gas in a Cylinder of compressed air is not hotter than the air outside of the cylinder.
L, ta.
Din, a thermometer measures number of collisions.
Your cylinder example is nonsense. Once full, no further work is done on contents, so it cools down. T
In free atmosphere, there is constant work being done on lowest layer, all the molecules above and below are constantly bashing into it (or swapping places with some in lowest layer). It's a gas!!!!
Never thought I'd reference this, but my university dissertation supervisor Hasok Chang wrote a book called measuring temperature, and it's very good.
Thermometers do not measure the number of collisions as temperature , if they did then a thermometer that is experiencing more collisions in a high density gas would measure hot , and they do not do that. Once the thermometer is in equilibrium with the gas the kinetic energy of one molecule of the thermometer is the same as the kinetic energy of one molecule of the gas , and the reading corresponds to that.
Din, just give in.
If compressed gas is allowed to cool, then molecules moving slowly again = fewer collisions.
Number of collisions depends on how many molecules AND how fast they are moving. Duh.
MW / Din. Like molecules my grandchildren get excited and run about colliding into me, the furniture and each other. They get hot. They stop all that and they cool down.
No that is wrong again.
The number of molecules does not increase the temperature. If it did then putting more molecules in the gas cylinder would increase its temperature , and it does not do that .
I have explained it 8 times now starting with my comment Monday 2 march about the car tyre.
and then again and again
Monday 2 march - Temperature increase not necessary for increase of pressure. For example car tyres are not warm.
and again
Regarding the ideal gas law, rearranged for temperature, T=(PV)/(nR). when V decreases, P increases and so the Temperature stays unchanged. Volume decreased and Pressure increased.
and again
. Look at the Gas Law for yourself. PV=nRT .Compared to an uncompressed gas , a compressed gas has a smaller volume a higher pressure and the same temperature. PV=nRT.
and again
- Temperature is not the aggregate Kinetic energy of group of molecules. It is the average kinetic energy of the single molecules in the group. More molecules in fixed a volume of space is not a temperature rise for that volume of space.
and again
-
It is not an undisputed and observable fact that temperature difference is caused by more molecules being in a given space , that, is explicitly not the case.
The kinetic energy of a gas molecule is not increased by proximity to other molecules.
and again
The rate of collisions is not how we measure temperature.
Once there are enough collisions with the thermometer occurring for the thermometer and gas to be in equilibrium then for a greater rate of collisions no further heating of the thermometer occurs and the thermometer gives the correct reading of the gas temperature.
That is demonstrated by the fact that the gas in a Cylinder of compressed air is not hotter than the air outside of the cylinder.
and again
Thermometers do not measure the number of collisions as temperature , if they did then a thermometer that is experiencing more collisions in a high density gas would measure hot , and they do not do that. Once the thermometer is in equilibrium with the gas the kinetic energy of one molecule of the thermometer is the same as the kinetic energy of one molecule of the gas , and the reading corresponds to that.
D. Well when tyres heat up the pressure rises. Friction on tyre generates heat. That heat transfers itself to the gas molecules in the tyre and the pressure rises. I have carried out practical experiments on this. Race car tyres at start and cold. 22 front. 24 rear. After 30 min race hot and about plus 2 psi each end.
L, the tyres are a good example. The road surface is constantly doing work on the air in the tyre, bashing into it and compressing it.
It's the same with the bottom layer of air, molecules from above are constantly bashing into it and compressing it into the ground, keeping it at slightly higher density.
Thanks!
Quote " It's the same with the bottom layer of air, molecules from above are constantly bashing into it and compressing it into the ground, keeping it at slightly higher density "
And once again . That is totally wrong. Temperature of a gas is not an attribute of its density.
And so that now increases the tally of the times I have explained it by one more, and so now the total is now 9 times.
D / MW It's a fact that air, the atmosphere is denser at ground level then at height.
It's also a fact that it's warmer at ground level than at height.
Generally, as I understand it, heat is molecules getting excited - in gases and solids. It's energy.
I understand that compressing a gas heats it up. If it didn't the diesel engine would not work.
Also all ICE's are happier when the atmosphere is 'dense'. You get a denser charge and some water injection effect.
D I agree that temp is not a function of density. But it might be that sunlight heats up upper layer of less dense atmosphere which makes it excited such that molecules bump into each other and transfer that heat to lower layers.
Also sunshine heats up land and sea which also transfer heat back to the atmosphere when night falls.
I think D is being a bit obtuse as you each seem to be arguing about the same thing.
And anyway the whole 'carbon crisis' meme is akin to selling indulgences by the mediaeval R Church. In short it's a scam to control us.
Hi Lola
Mark and I are not "arguing arguing the same thing"
Mark has posted a blog prompting input on a subjec.
That blog and then the comments repeats over and over again a fundamental misconception of gas , that pressure or density entails temperature. That is not the case. It is fundamentally wrong.
"If it was the temperature then a cylinder of compressed air sitting in a room would be hotter than the surrounding air in the room. And a cylinder of compressed air is not hotter."
Yes it is, when the air is compressed, then it cools down by conduction to the same temperature as the uncompressed air outside, which means that the molecules of compressed air then have less energy each than the molecules of uncompressed air outside the cylinder. That this is the case can be seen by allowing the compressed air to escape from the cylinder, when it is then cooler than the surrounding air with which it is mixing. This is how a fridge works.
"Re 7. It's not conflating two effects. They are two sides of the same coin; they are in balance. Each influences the other, it doesn't matter which you start with to explain or predict the other. And can we stop going on about "extra heat being added". I point out several times that I am looking at an equilibrium situation, a calm, still night."
If there is equilibrium, why are you saying "The molecules at the surface can't rise to dissipate heat (as some people argue)"? At equilibrium, nothing is trying to rise. That's what equilibrium means.
"B, "All of which leaves us with one figure, the only one not derived from direct observation, which is the 33K difference caused by the presence of the atmosphere as the one that questionable."
Well, you prove that the figure is wrong, then you do a post explaining why it gets colder as you go higher up."
I'm not saying the figure is wrong, I'm just saying that since you have pointed out that something is wrong, i.e. "it's colder than expected higher up.", that if any figure is wrong, then that is the most likely culprit. This is logic, not science, so no proof necessary.
" It explains why it's warmer at sea level and cooler on Mount Everest."
You mean without involving CO2? yes, but surely any fule kno that.
"Your cylinder example is nonsense. Once full, no further work is done on contents, so it cools down."
It is, as I have pointed out, but
"In free atmosphere, there is constant work being done on lowest layer, all the molecules above and below are constantly bashing into it (or swapping places with some in lowest layer)."
is not the answer. If the gas is at equilibrium, which it is for the purpose of this thought experiment, then, by definition, no work is being done to it. Conversely, if work is being done to it, it is not at equilibrium.
"L, the tyres are a good example. The road surface is constantly doing work on the air in the tyre, bashing into it and compressing it.
It's the same with the bottom layer of air, molecules from above are constantly bashing into it and compressing it into the ground, keeping it at slightly higher density."
I think that counts as sympathetic magic,(i.e. things that look or behave the same, are the same) which stopped being believed in at around the late C17th. The road surface is not doing any work to the tyre, the forward movement of the car is doing the work and the work is being done to the tyre, not the air, which remains at the same pressure throughout each revolution. This is not at all the case with the air, where no work is being done to it at all.
"I agree that temp is not a function of density."
Well it is and it isn't. It's a function of energy density. There is more heat energy in a bath full of tepid water than a kettle full of boiling water, but the energy density of the water in the bath is much lower (more heat, but much greater volume) than that of the water in the kettle ( less heat, but much smaller volume). Since a vacuum cannot contain or conduct energy, the energy in a gas must all be carried by its molecules, so, for a given volume of gas and a given amount of energy to each molecule, the greater number of molecules in the volume, i.e. the higher the density of the gas, the greater the amount of heat in that volume of gas. The greater the amount of heat contained within a given volume of gas, the greater the temperature of that volume of gas.
L, thanks again. This sort of stuff is easy to understand if you think about everyday examples like car tyres.
B, no point discussing further - why don't you do a post on the Gravity Thermal Effect?
B 'energy density'. Agreed. And that's why petrol and diesel are such good fuels. They have very high energy density. Whereas batteries don't.
Which, ultimately is what has triggered all this discussion.
B 'temperature' and 'heat' are different things.
"B, no point discussing further - why don't you do a post on the Gravity Thermal Effect?"
Do you know, that's just the sort of reply I'd expect from a Warmenist: "Stop arguing, I'm right."
"'temperature' and 'heat' are different things."
If you read my last comment again, you will see I said just that (the bit about the bath and the kettle).
B. I missed that. It did not read that way to me.
Post a Comment