Guest essay by: Thomas E. Shula
Rancho Mirage, CA
The figure below, published by NASA, is one example of many that attempt to visualize the various factors in the “Energy Budget” of the Earth. The yellow arrows on the left depict the incoming solar radiation. It is in part absorbed by the atmosphere, partially reflected into space by clouds and the atmosphere, partially reflected by the surface of the Earth, and a bit less than 50% is absorbed by the surface of the Earth and converted into heat. On the right, the red arrows depict the paths that transport the energy from the Earth’s surface to space, as postulated by the greenhouse effect. This model of the “Energy Budget” is the basis of climate models attempting to predict the effects of hypothesized Anthropogenic Global Warming (AGW) from greenhouse gases.
Diagram Courtesy of NASA
As the inset paragraph in the NASA diagram states, “On average, and over the long term, there is a balance at the top of the atmosphere.”
The values associated with each of the arrows in the diagram are the corresponding energy fluxes in Watts/m2. These values are derived in different ways, some of which are relevant to this exposition and will be described below. These values are used in climate models and may vary as the models evolve, though typically not by much. Some typical values from a NASA document can be found on page 16 HERE.[1] Certain assumptions led to the development of the Greenhouse Gas Theory. One of the conclusions explained at Earth Temperature without GHGs – Energy Education[2] is that without greenhouse gases, the earth would be approximately 33 C cooler, essentially an average temperature near freezing. This is the result of treating both the Earth and its atmosphere as blackbodies following the Stefan-Boltzmann Law, as is discussed in this VIDEO[3] from an online course about climate modeling.
From the energy budget diagram, there are four red arrows corresponding to (average) longwave (Infrared) radiation flux. They are as follows:
- 398.2 Watts/m2 longwave radiation upwelling from the surface
- 18.4 Watts/m2 upward from conduction/convection
- 86.4 Watts/m2 upward from evapotranspiration
- 340.3 Watts/m2 longwave radiation downwelling from the atmosphere as Back Radiation
According to the greenhouse effect, it is the downwelling Back Radiation that “traps” the heat in the atmosphere to keep the Earth warm.
For purposes of this exposition, we will consider only first two components above, as we will be investigating the relationship between upwelling longwave radiation and conduction/convection at the Earth’s surface. According to the model explained above, 398.2 W/m2 represents approximately 95.5% of shared heat transport and conduction/convection approximately 4.5% of shared heat transport.
How might we measure this? We know that there are three mechanisms for transport of heat energy: conduction, convection, and radiation. One needs to design an experiment that can discern the proportion of heat loss due to radiation versus the heat loss due to conduction and convection. It so happens that there is a common instrument that has been in use for over 100 years that does precisely this.
The Pirani Gauge
This image was provided with permission by MKS Instruments, Inc. (Andover, MA)
The modern Pirani Gauge is used to measure vacuum in the range from 760 Torr to 10-4 Torr, though some are designed to measure higher pressures up to 1000 Torr. It was invented in 1906 by Marcello Pirani, a German physicist working for Siemens & Halske, and has been used in a myriad of applications for over 100 years. The operating principle of the gauge is simple. Inside the gauge body there is a filament that is heated and maintained at a constant temperature. The energy going into the filament is controlled via the current flowing through it. Energy can be dissipated from the filament in four ways:
- Gas Conduction
- Gas Convection
- Radiation
- End Losses (i.e., conduction of heat from the filament to its support structure.)
The Radiation and End Losses are constant and can be measured by creating an adequate vacuum inside the gauge so that losses from conduction and convection are negligible. When gas is introduced to the enclosure, heat is removed from the filament via conduction and convection. The input power required to maintain the temperature of the filament will depend on how much energy is being removed via conduction and convection by the gas. In summary, the Pirani gauge tells us the relative contributions to heat transport by radiation versus conduction/convection as a function of gas pressure for an object (the filament in this case) held at a constant temperature. Referring to the paragraph preceding the above image, this is exactly the measurement we are looking for.
The response curve for a typical gauge is shown in next illustration. Both illustrations can be found in the Technical Note “Introduction to Vacuum Pressure Measurement” published by MKS Instruments, and the specific gauge illustrated in the figure is an MKS Instruments convection enhanced Pirani gauge.
This image was provided with permission by MKS Instruments, Inc. (Andover, MA)
The red line in the chart represents the (constant) total radiative and end losses of approximately 0.4 mW. The blue line represents the power loss due to gas only, and the green curve that flattens out on the two ends represents the total loss, i.e., the total energy input required to maintain the temperature of the filament as a function of pressure. At atmospheric pressure, 760 Torr, the power required to maintain the temperature of the filament is 100 mW. Since the radiative and end losses are 0.4 mW, this means that the heat transport by gas is 99.6%, with only 0.4% due to radiative and end losses. This should not be surprising, because all gas molecules can transport heat via conduction and convection, not just the tiny fraction that constitute the so-called “greenhouse gases.”
We can also consider the case of a vacuum pressure of 10 Torr, the equivalent of about 110,000 feet above sea level. In this case, about 60 mW of power is required to maintain the filament temperature, so the gas is still accounting for about 99.3% of heat transport with radiative and end losses only 0.7%. As one goes higher in altitude a larger proportion of the heat transport is attributable to radiation, and that is how all the heat eventually returns to space in the extreme upper atmosphere. The crossover point, where gas losses are equal to radiative and end losses, is at about [20] milliTorr (.02 Torr), equivalent to an altitude beyond 250,000 feet. The response of the Pirani gauge is independent of the enclosure it is in or the lack thereof. If we took a “naked” Pirani gauge to an altitude where the atmospheric pressure is 10 Torr, the response would be the same as if it was attached to a vacuum system at a pressure of 10 Torr. There have been Pirani gauges made in many different sizes and configurations, some with radiative losses on the order of 0.1% at standard atmospheric pressure.[4]
The filament in the Pirani gauge is analogous to the surface of the Earth. The gas molecules collide with the surface and absorb energy raising their effective temperature (conduction). A “bubble” of this warmer gas then rises relative to the cooler gas around it as the cooler gas drops to the surface and repeats the cycle continuously (convection). This cools the surface and is perfectly illustrated by the response of the Pirani gauge. This is well understood by those who have worked with high temperature processes in vacuum systems, and no doubt by many others. The author can only speculate regarding why this has not been given consideration earlier.
Conclusions
The Pirani gauge provides a method to measure the relative contributions of radiation vs. conduction/convection to heat transport in a gaseous environment as a function of pressure. At pressures relevant to the lower atmosphere (troposphere + stratosphere) radiation accounts for less than 1% of the upward heat transport. This does not refute the existence of said radiation in the lower atmosphere, it only demonstrates experimentally that its role in upward heat transport is insignificant.
It has been demonstrated via the Pirani gauge operating principle that upward heat transport via radiation plays an insignificant role in the transport of heat at atmospheric pressures from the surface to the upper stratosphere. The greenhouse effect, if it exists, is based on upward heat transport via radiation in the lower atmosphere. Therefore the greenhouse effect, if it exists, plays an insignificant role in heat transfer and, by extension, the energy balance of the atmosphere.
Contemporary climate models are based on energy balance models of the type depicted in the NASA diagram at the beginning of this paper. It is clear from the NASA diagram as well as similar diagrams from other sources that the fundamental assumption of these models is that radiation is the primary driver of upward heat transport in the lower atmosphere. Because radiation is an insignificant driver of upward heat transport in the lower atmosphere, these models are based on a false assumption and are therefore invalid. Finally, because the models are generally intended to support the theory of Anthropogenic Global Warming because of the greenhouse effect, there is no scientific evidence for the greenhouse effect or Anthropogenic Global Warming.
The radiation energy that the Earth absorbs from the Sun arrives at the speed of light. The Earth loses heat at a speed driven by convection in a process we call “weather.” Weather is the chaotic process by which the Earth’s atmosphere continuously tries to reach thermal equilibrium but never succeeds. The convection takes place continuously, but the speed at which heat is transported by convection is MUCH slower than the speed of light. This means that heat energy leaves the Earth more slowly than it arrives, and that is why the Earth is warmer than predicted by the Stefan-Boltzmann Law.
Appendix
(April 11, 2023)
How did “Climate Science” get this so wrong?
The two fundamental assumptions leading to the Greenhouse Effect are that 1) The primary mechanism by which the surface of the Earth loses heat is radiation and, 2) Based on the Stefan-Boltzmann Law the temperature of the Earth’s surface should be 33K cooler than what we observe.
The Stefan-Boltzmann Law (SBL) defines a blackbody (which is an idealized object that does not exist in nature) as having the following characteristics:
- It exists in an environment at 0K, i.e., a perfect vacuum.
- It is in equilibrium with its environment.
- It is a perfect absorber of radiation.
With certain adjustments such as emissivity, the SBL provides a convenient means of measuring the temperature of an object based on its emitted radiation even in non-ideal environments. The estimation of the temperature of stars for example, and the use of infrared cameras to detect “hot spots.” One must be careful, however, to keep in mind that it is only the “idealized” black body that behaves strictly according to the SBL.
The Earth and its atmosphere do not satisfy any of the conditions of SBL. Additionally, it has become common to ignore condition number 1 above. If one looks up the definition of a blackbody, a reference to the 0K (perfect vacuum) condition is often not mentioned. This typically has little effect when it comes to temperature measurements using optical techniques, but it is extremely important in understanding the dynamics of heat transfer in, for example, terrestrial conditions.
This is neglected in climate models. It assumes that with the surface temperature of 288K the power radiated upward from the surface is 398 Watts/m2 and that it is all longwave IR radiation. It then becomes necessary to “balance” that upwelling radiation with “back radiation” to obtain “radiative balance” in the atmosphere.
What is happening is quite different. At 288K temperature the photon flux (generously assuming it is all at 15 micron wavelength to maximize the number of IR active photons) is approximately 3X1022 photons/sec-m2. That is a lot of photons, and if the surface was in a perfect vacuum that radiative flux would be the only way for the surface to release energy.
But we have an atmosphere. At standard temperature and pressure, air has some very interesting properties. It is much denser than we typically imagine.
Average molecular velocity approximately 470 m/sec (1050 mph, supersonic at the macro level)
Molecular collision frequency (each with another) approximately 7,000,000,000 collisions/sec (7 GHz)
Mean free path approximately 70 nm (about 1/10 wavelength of visible light)
Frequency of collisions with an ideal planar surface approximately 3X1027 collisions/sec-m2
To put this in perspective, the last number is quite useful. The average surface area of an adult human is around a square meter. That means that each second about 100 lbs. of air molecules collide with each of us with an average speed of about 1050 mph. More importantly, given the photon flux at 288K this means that approximately 100,000 air molecules collide with the surface for each potential infrared photon emitted. Because the energy transfer from collisions will change the equilibrium at the surface by removing energy through conduction, it is likely that the actual emitted photon flux will be even less. To believe that radiative transfer is the primary mechanism for upward heat transfer at the Earth’s surface would mean that one IR photon would transfer more energy than 100,000 molecular collisions. These numbers are for a perfectly smooth planar surface. The actual surface area at an atomic level can be much greater.
Clearly, the interface between the surface of the Earth and the atmosphere is an extremely chaotic place at the atomic level. This gives perspective to explain what we see in the operation of the Pirani gauge as explained in the body of this paper.
References:
[1] Kelly, Schmidt, et al, GISS-E2.1: Configurations and Climatology
[2] Earth Temperature without GHGs – Energy Education
[3] (224) Climate Dynamics Lecture 02 Energy and the Earth System – YouTube
[4] Fabrication of thermal‐based vacuum gauge – Jung – 2014 – Micro & Nano Letters – Wiley Online Library
The measurement uncertainty of radiometric quantities obtained with thermopile instruments is on the order of about ±3-4% at best. For irradiance levels of 200W/m2, this corresponds to ±6W/m2. Making balance calculation with resolutions of 0.1W/m2 as the NASA diagram does cannot be justified. Some versions of these energy balance diagrams claim resolutions 0.01W/m2.
Thanks for your comment. I am in agreement with you. I use these values because they are what appear in the NASA diagram. What you may not know is that the values for OLR for the surface OLR emission and “Back Radiation” are not based on measurement. They are based on the assumption that the surface of the Earth and the atmosphere are both blackbodies emitting radiation according to Stefan-Boltzmann Law at temperatures of about 288K and 277K, respectively.
An Eppley Labs PIR measures long-wavelength hemispherical IR directly by virtue of a silicon dome:
http://www.eppleylab.com/instrument-list/precision-infared-radiometer/
Here are some example data, the black curve in the real-time daily irradiance graph:
https://midcdmz.nrel.gov/apps/gdisplay.pl?BMS
This article is full of mistakes.
The atmosphere becomes more opaque to infrared radiation. It does not trap the heat. Solar energy is trapped in the ocean, and the atmosphere is warmed from the surface, mainly by convection and latent heat, and by direct absorption of shortwave solar energy. 93% of the energy increase from global warming resides in the ocean because the atmosphere does not trap heat.
Heat is not transported to the upper stratosphere. The average height of emission is about 5 km. The air that enters the stratosphere through the tropical tropopause is extremely cold and dry. Nearly all heat in the stratosphere is coming through direct solar shortwave absorption mostly by ozone, and infrared absorption from CO2.
If this were true the Earth would warm continuously cooking us all. Energy leaves the Earth as infrared radiation at the speed of light, and essentially the same amount as it arrives. There’s quite a lot of solar energy residing in the Earth’s climate system, but once it warmed eons ago, nearly the same amount that comes in goes out, at the same speed.
There’s very little understanding throughout the article of how climate models work, how the energy budget has been determined, and how the climate system functions.
So you agree that NASA has it wrong as the author pointed out.
This is how NASA explains Greenhouse Gasses:
https://climatekids.nasa.gov/greenhouse-cards/
The concept of “trapping heat” needs to be eliminated from scientific discussion. Heat, by definition, is never trapped, it is thermal energy in motion.
“In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not contain heat. Nevertheless, the term is also often used [incorrectly] to refer to the thermal energy contained in a system as a component of its internal energy and that is reflected in the temperature of the system.” Wikipedia
Tell NASA and the IPCC:
https://www.ipcc.ch/2019/05/13/ipcc-2019-refinement/
All the authors involved in what the IPCC spews are complicit in this unscientific cla[trap. If they weren’t they would publicly declare their position.
They do declare it (subtly)… The Physics of Atmospheres, by John Houghton:
“The glass in a greenhouse possesses similar optical properties in that it is transparent to solar radiation and opaque to infrared. Although known as the ‘greenhouse effect’ it might be noted that in practice it only provides a MINOR CONTRIBUTION to the warmth of a greenhouse that is largely due to the suppression of air motions within it.”
Sir John Theodore Houghton CBE FRS FLSW (30 December 1931 – 15 April 2020) was a Welsh atmospheric physicist who was the co-chair of the Intergovernmental Panel on Climate Change’s (IPCC) scientific assessment working group which shared the Nobel Peace Prize in 2007 with Al Gore.[2] He was the lead editor of first three IPCC reports. He was professor in atmospheric physics at the University of Oxford, former Director General at the Met Office and founder of the Hadley Centre.[3]
I’ve also sometimes thought that ‘traps’ heat was an odd choice of wording. However, this wording could mean different things depending on how you visualize it.
As one analogy, say you see a steady whirlpool in the bits of debris going down a wild and rapid canyon stream. If this means that some portion of the water flow is being recycled, maybe you could interpret that as meaning that the overall effective speed of flow is slower, because some of the water is ‘trapped’ (in the sense that there is some circulation going around and around whatever rocky formation is ‘whirling’ the water). This might even mean that the water level, and therefore the pressure, upstream of the whirlpool would be a bit higher than if the ‘whirl’ were not present. So, maybe this is sort of like expecting a higher temperature at the earth’s surface level in the GHE picture, if only some heat power flow were seen as ‘caught in a whirl’ somewhere between earth and sky?
If I relate this conception to the “Earth’s Energy Budget” figure in the article, the diagram shows 163 watts of primary solar energy being absorbed by the ground, but 398 watts radiating “from’ the ground, so there’s an “extra” 235 watts of IR heat energy being produced by the ground somehow! This is supposed to come from the atmosphere in a kind of circle, an extra ‘go around’ for the power flow, a ‘back radiation’ really.
Generally speaking, I find it difficult to visualize how radiant energy at the surface could be boosted up or transformed up significantly in this way. Not that it seems impossible, but it just seems like there has to be more to the story, like a heat pump effect actually moving heat down in a more ‘active’ way perhaps? Say, Hadley cells shoving heat down along with descending air packets, maybe?
If weather systems and/or air circulation patterns were capable of putting some *work* into moving heat around, that might present some sort of alternative to having large amounts of IR flux ‘doubling up’, by way of circling back around on itself. Maybe this is even what the article writer here is trying to get at, using a Pirani gauge as an indicator of how relatively small IR effects could be, at least in some circumstances.
David, I and others have pointed this out several times. It is worth saying again and again. Thanks.
Another WUWT classic 😉
Downwelling long wave radiation has decreased since 1983. Downwelling shortwave has increased from 1983. From Y. Zhang and W. Rossow’s paper “Global Radiative Flux Profile Data Set: Revised and Extended”.
This is the opposite to the global warming theory. The warming can’t be CO2 because warming from CO2 is dependent on causing increasing downwelling longwave radiation.
Longwave radiation is not going into the ocean, its going out to space.
Decreasing downwelling longwave radiation has cooled the earth by approximately 4 watts per squ m since 1983, the satellite era.
Also, Y. Zhang and W. Rossow are NASA GISS scientists, and their paper can be found on the CERES website. Publications – CERES (nasa.gov) . They are not “climate deniers”.
It is not opposite to my global warming theory. As the planet warms the downwelling radiation decreases. The decrease is then replaced by the effects of increased atmospheric heating primarily from latent heat. This allows the planet to come to a new slightly higher equilibrium temperature.
The important fact is that the magnitude of the GHE is partially dependent on the lapse rate. The GHE of warming the surface puts more moisture into the atmosphere lowering the lapse rate. A lower lapse rate decreases the downwelling radiation as we see in the data.
Your lapse rate effect makes the atmosphere more superadiabatic and more unstable. That is the key. This instability drives more heat by fluid dynamic heat transport to the effective radiating height. One cannot have your effect without a dynamic response.
It is not a coincidence the ratio of atmospheric absorbed LW radiation to OLR being 3:2 exactly matches the ratio of the adiabatic lapse rate to the environmental one. That is the regulating mechanism.
Your first paragraph and my description of global warming agree in the sense that if the downwelling is decreased then the upwelling is increased.
still have a problem in the second because I don’t believe the atmosphere absorbs LW radiation other than momentarily. I would refer to that energy as LW radiation not radiated to space. I haven’t thought about the significance of the two ratios, but I can see how it could be the regulating mechanism..
Earths Energy Imbalance (EEI) is the keystone of the climate science. Out going longwave radiation cools the planet.
“increasing CO2 and CH4 abundances, which should produce an increase in LWdn, all other things being equal; but as Figure 3 (lower panel) shows, the near-surface air temperature (Ta) and skin temperatures (Ts) from ISCCP-H used in FH are generally decreasing slightly. The magnitude of the decrease over the record is only about 1 K” from Y. Zhang and W. Rossow’ 2023 paper. Attached is figure 3.
This means that Earths Energy Imbalance (EEI) at the top of the atmosphere is negative.
That’s actually a convoluted and incorrect way of looking at it. Outer space, cloud bottoms, and greeenhouse gases give the “Sky” an average temperature that is warmer than the temperature of outer space.
Thus on a set of Plank curves where the heat transferred is represented by the area between the two temperatures, the slightly warmer sky temperature due to additional greenhouse gas….lets less radiation escape from the surface, so the sun will heat the surface a little more the next day until heat out=heat in again.
The “sky” is a gas so Plank curves are not applicable. The gasses radiate in bands, not curves.
James, I’m talking about averages of clouds (nearly a BB), outer space (a BB) in the atmospheric window wavelengths, greenhouse gases (look like a BB of the wrong temperature to sensors with outer space as a background).
This is a much better mental picture to have than “back radiation trapping heat” or “heat escaping slower due to convection” that require an additional level of thought gymnastics.
Dr. Vinos:
You jumped the gun. Mr. Shula is exactly correct, and you just misinterpreted his (justifiably) complex arguments. Your criticisms are entirely misdirected. Or else you are not understanding the big picture. And basically, otherwise, you are in complete agreement with him.
So am I. He is a true scientist, analyzing reality in terms of experimentally proven mechanisms, not dream-like, mathematical fantasies. Thank you, Mr. Shula.
David Solan
I totally agree. The experimental proof is before you that radiative effects are tiny compared with other transport mechanisms. Last time I attempted to refer to textbook thermodynamics with this remark I got a lot of negative points. I had however failed to realise that the Pirani gauge was the proof my comments needed. Never mind. Now all we have to do is ask NASA to withdraw their diagram from everywhere and substitute a real one! Of course this will not happen, politicians never admit anything they have ever said is incorrect, and usually tell the opposite story later as typical hypocrites always do. The Climate nonsense needs to stop now, but I doubt that it will!
On the other hand, the only way the planet loses energy to outer space is by radiation. We’ve had satellite measurements of upwelling LWIR for decades.link The spectra clearly show the energy absorbed by CO2. In that light, I don’t think the Pirani gauge proves much.
Also, the problem isn’t that CO2 absorbs LWIR at a particular wavelength. Increasing atmospheric CO2 should provide a slight beneficial warming. The only way ‘they’ can make CO2 a problem is to posit a positive feedback involving increased water vapor.
Fully agree. CO2 is a stick ‘they’ are using to destroy modern civilization, kill billions of people, and drive us back to the stone age.
I could not have put it better myself. Thank you!
The climate is extremely complex and we all get it wrong on some things. Mr. Shula should take the opportunity to learn from my critical comments, as I continue to learn from others.
The big picture science-wise is that there is an energy imbalance at the top of the atmosphere, proportional to the warming rate, whose cause has not been properly determined. Experimenting with a Pirani gauge will tell you nothing about the imbalance or its cause.
Javier wrote: “there is an energy imbalance at the top of the atmosphere”
Are you sure about that, Javier? How was that “energy imbalance” measured, and what are the error bars on it? The last time I checked, the error bar was larger than the claimed “imbalance”, by about an order of magnitude, so it is just as accurate to say there is no “energy imbalance”.
Thank you, David, for the kind words and support.
“If this were true the Earth would warm continuously cooking us all. Energy leaves the Earth as infrared radiation at the speed of light, and essentially the same amount as it arrives.”
You couldn’t be more correct. It seems that those trying to use “radiation budgets” fall prey to the same meme as climate scientists – the use of averages instead of integrals of a time series.
As the temperature of the earth goes up, so does the amount of radiation it emits. It even does this during the day. If the heat was really trapped we would see a continuous rise in the number of record high temp days. Yet, at least in the US, he number of 100F days has been going down for at least two decades if not longer. That should be an indicator that there *has* been increased radiation from the earth preventing it from getting higher and higher temps.
If Tmin has been going up then that means the exponential/polynomial decrease in temp at night begins at a higher radiation level thus dumping more heat at the start.
I suspect that the amount of heat being dumped is related to T^3, the rate of change of the radiation.
Averages don’t tell the whole truth, figures lie and liars figure. Only the integral of the radiation curve can tell the truth about how much heat is being dumped. A radiation-day figure similar to the degree-day if you will.
You have misquoted Mr. Shula by not citing the exact words in the post. The full sentence is “According to the greenhouse effect, it is the downwelling Back Radiation that “traps” the heat in the atmosphere to keep the Earth warm.” (emphasis added) Mr. Shula then goes on to show that this concept is wrong in his view.
“There’s quite a lot of solar energy residing in the Earth’s climate system, but once it warmed eons ago, nearly the same amount that comes in goes out, at the same speed.” please explain – if the energy leaves the earth in the same amount as it entered how did the earth warm eons ago? What was different then than now?
Thank you for your comments. I will attempt to address them one at a time.
I suggest you consider what would happen if, for example, the rotation of the Earth changed and we had either a 48 hour day or a 12 hour day. What would happen to min/max temperature variation on a daily basis?
Don’t we see that in the Pole regions. Especially in winter when we have continuous night.. Luckily the formation of sea ice prevents Earth from losing even more heat.
Very nice post Tom. When I read Javier’s criticism I was going to fire off a few friendly rebuttals, but you have already done it.
I would just like to offer a bit of further rebuttal of Javier’s suggestion that if heat is not leaving as fast as it enters, there must be continuous heating. No, that is not right, and I think your speed-of-heat-transport way of looking at it works even if the same side of the planet always faced the sun. It would still be hotter closer to planet surface, and this can be understood in terms of miles per hour.
Look at the analogy between the flow of electricity in a wire and the flow of water in a river. Voltage is often likened to the speed of current in a river and amperage to the cross-sectional area of the river, or the depth, if the width of a river is constant.
The total flow of water is then likened to the total flow of electrical power (watts = volts x amps). At points a given river may flow faster or slower, while at any point along the river, the amount water crossing at that point will be the same.
Extending this analogy to heat energy that is transported up from a shortwave-warmed planetary surface, the transport in one direction can indeed be slower so long as the cross-sectional area of the flow is larger in that direction, even in steady state, where the planetary system is in energy balance (not warming).
Speed, as you were using it, was not metaphorical. Shortwave comes in at the speed of light. When it is transported back out by convection and conduction, it moves at anywhere from a snail’s pace to mostly modest wind speeds.
The “cross sectional area” these speeds are multiplied by to get the rate of upward energy transport is just (in the case of convection) the temperature difference between the rising air and the air that it displaces. Similarly for conduction: how much heat increase at what upwards speed? Plus the relatively small amount of energy that by your calculations get transported upward at the speed of light through long-wave radiation.
At every elevation this tally must equal incoming radiation, or there will be heating or cooling somewhere.
The different speeds at which the different avenues of heat transport operate do not mean they can’t be carrying the same amount of energy, but I think that they do imply hotter temperatures near the surface, just by looking at the process sequentially.
When the sun first comes up the planet surface immediately starts warming, but that heat can only rise at very modest speeds, so that initially it is only the surface that warms, and this asymmetry continues until equilibrium is reached: when enough heat gets high enough in the atmosphere for radiation out to equal radiation in (whether the surface rotates through night and day or not).
So that’s my tidbit of extra rebuttal. Overall my first reaction to Tom’s wonderful analysis is very similar to my first reaction to Javier pointing out that poleward energy transport is the key to understanding climate regulation, since the poles are where the heat has an open escape hatch: “Of course!” Haha.
Very good both of you. Real climate science making real progress, in contrast to the 100% politically-funded crap from the phony bought and politicized “consensus.”
The only net upward radiative flux is that which is transmitted via the window.
Such diagrams depict a non existent radiative discontinuity at the surface.
Using their figures:
398.2 – 340.3 = 57.9.
57.9 – IR window 40.1 = Radiative discontinuity 17.8
Boundary layer turbulence eliminates this discontinuity.
Attribute the 17.8 to boundary layer sensible heat flux which circulates in the planetary boundary layer.
340.3 + 17.8 = atmospheric absorbed flux = 358.1 = near surface average available heat equivalent.
Not a purely radiative phenomenon.
358.1 / OLR 238.9 = ratio 1.5.
3 units absorbed to 2 units emitted.
There can be no net radiative flux within atmosphere. The can be no unnatural LW radiative forcing.
“There can be no net radiative flux within atmosphere”.
I state that as “All radiation that enters the atmosphere leaves the atmosphere”. Nobody seems to believe it. Of course I follow it with it either returns to the surface or leaves to space. The idea of down welling back radiation is not very popular around here. But I try to educate.
I assume you believe that radiation from a cold body to a hotter body also occurs? It is not normal for the atmosphere at even a few hundred feet to be warmer than the surface, which is implied in all these “models”. It is illustrated by the warm tropical “hotspot” in the atmosphere models which does not exist! A thermocouple in the top mm of the surface reads the air temperature quite accurately, no radiative energy transfer can occur under these conditions. Does the atmosphere get hotter with height? Certainly not!
Radiation definitely flows from cold bodies to hotter bodies as well as from hot bodies to colder bodies. The laws of thermodynamics only state that the net flow of energy is from the hot to the cold.
Photons are emitted by any body with a temperature. They flow in all directions and will likely be absorbed if they encounter a body with a higher temperature. The higher temperature body is emitting a greater number of photons so the net flow of energy exchange is to the colder body.
DWM says:”Photons are emitted by any body with a temperature.”
Does this statement include all the gases in the atmosphere?
If so please tell us how much LWIR is emitted by N2 and O2.
Yes all gasses in the atmosphere radiate energy in the form of photons. To determine how much is LWIR you would have to look in their characteristic wavelengths.
They emit photons in the ultraviolet spectrum. I suppose there could be a 100% transparent gas. Don’t know of one.
N2 and O2 don’t emit photons at Earthly temperatures. Are transparent to IR….
N2 and O2 in the atmosphere emit IR radiation as a result of low level energy states excited by collisions with other molecules returning to the ground states. When they measure downwelling radiation that is what they are measuring.
As I understand gasses absorbing and emitting photons, the energy of the incoming photon has to be equal to or higher than an available energy transition of the molecule. Monatomic and diatomic molecules like argon, nitrogen, and oxygen do not have available energy transitions in the range of photons in the infrared range of the spectrum. These molecules do not have the vibrational and rotational modes that are of the energy levels found in IR light. Molecules composed of three or more atoms (water, methane, carbon dioxide, ozone, etc.) can store energy in the bonds between the atoms due to bending. These energy transitions have all been determined from the geometry of the molecule and are supported by spectroscopic measurements.
As you point out, nitrogen and oxygen do not absorb or emit in the IR band because they do not have any energy transitions that small. (They do have lower energy transitions in the microwave region). It takes much more energy to move a molecule of nitrogen from one energy level to another. Generally, photons are emitted by any molecule with a temperature high enough that the molecule is not in its ground state. For this discussion, we are interested in a fairly small range of frequencies and energies from the IR to the UV range. I think we need more research to quantify how much energy is moved through the atmosphere via radiation versus convection, conduction, and latent heat.
Which the problem with this article. The author states because the heat loss by radiation from a hot wire in a chamber with a surrounding is low that must be the case for the Earth transferring heat to outer space! The radiation loss from the wire is given by:
𝜀𝜎(Twire^4-Twall^4)
With a constant to allow for the relative areas of the wire and wall, due to the radiation back from the wall the radiative loss by the wire can be very small. This is why you can’t use the structure of the Pirani gauge as a model for the atmosphere.
I made a similar comment elsewhere.
To clarify, this article is not about radiation leaving the atmosphere going to outer space, though radiation is how the energy ultimately returns to space.
This is about what happens at the surface of the Earth. The climate models claim radiation from the surface is the primary mode of heat transport from the surface. That is not the case. Conduction of heat from the surface which then leads to convection is the primary mode of heat transfer from the surface into the atmosphere. That is what the Pirani gauge demonstrates. Once that energy manifests as kinetic energy, excited molecules higher in the atmosphere radiate the heat into space.
If you have not read the Appendix section of the article it is discussed in some detail there. Please note the strict statement of the conditions for the Stefan Boltzmann Law to apply. The first one is largely ignored.
In the Pirani gauge the material of the Wire is deliberately chosen so as to have a very low emissivity (0.05) to minimize radiation loss. The Earth however has a surface with an emissivity of about 0.95. Also in the Pirani gauge the wire is surrounded with a solid surface which is back radiating to the wire. Not a good model to the Earth’s surface radiation.
My understanding of the “enhanced greenhouse effect” is that what happens at the surface is not relevant; it’s what happens in the upper atmosphere that matters. Specifically, it’s the radiation rate from the level of unit optical depth out to space that determines the rate of cooling, and hence the equilibrium temperature. Clearly the height, and hence temperature, of this level is wavelength dependent. The CO2 (666 cm-1) band is the wavelength range of interest here. The claim is that, as CO2 concentration increases (throughout the atmosphere, but importantly here in the upper atmosphere) the height of the radiation level rises and the temperature drops, leading (via Stefan-Boltzmann) to less radiation to space, less cooling and a (very slightly) higher equilibrium temperature. With this mechanism it wouldn’t matter what was happening at the surface.
kTh^4 – kTc^4. Since Th > Tc, then the net flux is always from hot to cold. However kTc^4 is the radiation from the cold body. The photons go somewhere and don’t “know” the hot body is hotter. If there is no intervening cold body, then the net flux is greater.
Says the guy who didn’t like my previous Tsky description…
No I know that radiation occurs from a cold body to a hot body. It’s fundamental radiation heat transfer.
There can be no net LW radiative exchange between atmosphere and surface. The turbulent boundary layer enforces exchange equilibrium between surface and atmosphere by non radiative adjustments. The only net LW radiative flux is that which is transmitted directly to space. Only a static non dynamic atmosphere would allow a net positive LW flux between atmosphere and surface.
This is the main value of this device – so simple to show the different contributions of the heat transfer processes.
It would need to be painted black inside and out and have calibration curves for much lower body temperature to get a meaningful emission level but it is a brilliant device for such determination.
That would not exclude a net radiative exchange between surface and atmosphere. The surface can convectively exchange with the atmosphere, and the atmosphere radiate to space.
Net LW radiative exchange between surface and atmosphere is zero. Fluid dynamic flux should not be accounted for in radiation accounting.
We disagree. Downwelling radiation from the atmosphere is absorbed at the surface.
This is only true in a static concept. In a dynamic atmosphere there is no net gain of radiation received at the surface from atmosphere.
The troposphere is from Tropos, meaning change; dynamic mixing.
You could impose a virtual instantaneous anomalous surface absorption of atmospheric radiation, but it is immediately given back. The surface and atmosphere exchange equal amounts of LW. The only LW flux is that which is transmitted (upwards) to space.
Greenhouse enhancement hypotheses assume that increasing CO2 content will reduce surface transmitted LW flux to space. True.
Greenhouse enhancement hypothesis assume that this will increase the downward LW received by the surface. False.
The hypothesis requires putting a deliberate constraint on the dynamic response. The hypothesis only works by unnaturally limiting fluid dynamic transport. It only works by limiting hydrodynamic freedom.
While the transmissivity is reduced, the atmosphere becomes more instable. This increases the non-radiative flux from surface. The anomalous LW down can never be said to have been received by the surface.
Fluid dynamic flux dominates lower atmospheric heat transport.
The surface loses about 500 w/m2. Are you suggestion 500 w/m2 is returned to the surface entirely by dynamic action between the atmosphere at the surface and the surface with no contribution from downwelling? I don’t believe it.
You are failing to distinguish the radiative exchange component from the net flux. The only net radiative flux is that transmitted directly to space. The remainder is non-radiative flux, measured in Wm-2.
“ it only demonstrates experimentally that its role in upward heat transport is insignificant”
for a Pirani gauge. It says nothing about the atmosphere, where the length scales are totally different.
Agreed Nick. And there are no gradients of composition of active gasses; the filament probably has an emissivity of 0.02 to 0.04 which is utterly unlike earth materials which are all generally close to 0.9-0.95; and then there is the statement that the atmosphere is a blackbody described by the stefan-boltzmann law which is not just wrong, but very wrong.
I wish I could give you a +7 to at least reset you to zero. I don’t understand downvoting you when you are correct.
Emissivity has nothing to do with it. It’s an element(for heating). The energy leaving it is measured.
What you are saying is radiation is not important. Do hot things radiate or not? Why does the manufacturer list “radiation” if radiation has nothing to do with it?
Golly. John O’Hanlon’s excellent book on Vacuum Technology must be wrong! p. 83 in the 2nd Ed. “to extend the range of the gauge to lowest pressures it is necessary to reduce radiation losses…which can be minimized by reducing diameter and emissivity of the filament…”
The emissivity of a filament at a very high temperature is not 0.02 – 0.04!
Does the Pirani filament operate at “very high temperature”? No, it does not. The specifications of one such gauge indicate maximum operating at 65C. Thus the LWIR figure of emissivity is pertinent — 0.02-0.04 probably.
The wire is usually platinum which at a temperature of 260ºC is 0.05.
There we go! Low emissivity. Could also be nickel, tungsten, or gold plate (0.02) on any of these metals.
What is the emissivity of CO2 that is producing this 340 w/m2 in DWIR?
It is a function of temperature, total pressure, and partial pressure of CO2 times path length. You can look up the graphs in any engineering text on heat transfer or a text that focusses specifically on radiant transfer. Because the path has varying temperature and partial pressure in Earth’s atmosphere, the process requires step by step integration over the path. It is not as simple as “the emissivity”.
The inner shell is a radiation shield at the same temperature.as the filament. Radiative nett transfer is ideally zero by design. This is a pressure gauge that detects the gas losses hence the gas density.
i would guess pins 4 & 5 are a temperature transducer.
Also
Isothermal nett zero energy transfer is independent of emissivity, or you could paint yourself a free energy device.
Neither does a test tube full of carbonic acid
Here, from a textbook by Petty, is a true experimental result on the atmosphere. It shows the spectrum of down IR measured at 20 km above, Barrow Alaska. The gap between 600 and 700 cm^-1 quantifies the absorption by CO2 on an atmosphere scale. In the lower plot, looking up, the peak in this region shows the dominance of radiation from CO2 at the surface.
Can/does the emission of infrared change the pressure/temperature gradient exemplified in the lapse rate formulas?
We can use balloon data and skew-T diagrams to show that radiative effects are dominated by the pressure gradient. This is what the Connollys showed and what those two-not-to-be-named (initials N and Z) also showed, and what John Christy demonstrated in his analysis of satellite and balloon data for the tropical troposphere, compared with model projections.
Whatever cooling inhibition that’s happening due to CO2 is dominated by pressure effects. I believe this is close to what the lead author is saying.
In the graphic the “between 600 and 700 cm^-1″ anomaly is almost completely compensated further afield in the IR at between 500 and 600 cm^-1. This depicts the relationship between Co2 absorption spectra, and the compensating fluid dynamic response.
Petty is not measuring downwelling LWIR power at the surface with a room-temperature device. He is using a cryogenically cooled device in order for his sensor to be colder than the atmosphere. That is the only way he gets a positive power reading. But you knew that, right?
Nick
That is a very informative figure. Looking in the 14 t0 16 micron region you can see that all of the energy radiated from the surface in that band either radiates to space (top) or returns to the surface (bottom). Also you can see the weak downwelling from water vapor at shorter wavelengths. Another point, if you integrate under each curve you can get the total energy radiated from the atmosphere to space (top) and to the surface (bottom).for this region. For a more representative region of the Earth surface, the integration under the top curve would be close to 240 w/m2. Under the bottom I would guess to be close to 340 w/m2, the NASA number.
According to your plots when looking up you see something that is over 270 K. When looking down you see something that is about 225 K. The way I read what you said is those two things are exactly the same CO2.
It shows that when at 20km looking down the radiation in the 600-700 band is from CO2 at a temperature of 230K whereas looking up you see radiation from CO2 at ~270K.
Nick
Lillesand and Kiefer calculated that Earth’s emission spectrum only starts at 9um. (Wiens’ law). Fig. 5 of my report
An evaluation of the greenhouse effect by carbon dioxide | Bread on the water
That means that CH4 is not a greenhouse gas.
That means that the 4.3um absorption of CO2 does not cause warming, but cooling.
The nett result of more CO2 is nothing. The observed warming is actually caused by the observed greening.
I suppose you already gathered from my comment on Jennifer’s report elsewhere here that there is no warming caused by CO2 if minima in the SH keep dropping.
Is that a geology textbook you are citing?
Hi Clyde
Can you be more specific?
I’m asking the source for the Lillesand and Kiefer “calculation.”
3. Electromagnetic Spectrum | The Nature of Geographic Information (psu.edu)
Understand that the emission of earth is more discrete and does not follow a natural or even exact chi-square distribution.
Nick, please explain why distance makes a difference to heat transfer by radiation? What exactly is the mechanism you propose? Does the distance from the Sun change anything?
Inverse square law for incoming radiation, resulting in a net increase for absorption.
Nick,
Is it materially different from a Pt resistance temperature sensor for the purpose of this discussion?
They are used to infer processes in the atmosphere.
Geoff S
I’ve been saying this for years.
Envision an earth with only nitrogen in its atmosphere, but the same amount of atmosphere as now. According to some, earth temperature would drop by 33K. But it wouldn’t drop at all, it would increase. Why?
Because more solar energy would be absorbed by the surface, and ALL of that energy would have to be radiated away. The surface would HAVE to be hotter in order to radiate more. Radiation is proportional to temperature, so to radiate more, the temperature would have to be higher. You don’t need clouds or CO2 to understand this, you simply have to understand the thermal laws.
Note that, in this scenario, the atmosphere at the surface would still be heated by the surface, so it would be hottest in the daytime and coolest in the nighttime. We all know warm air rises by convection. But since nitrogen is not going to radiate any of this radiation away from earth, it requires that the surface cool below the ambient temperature of the atmosphere above it, and then conduction would deliver atmospheric heat to the surface, which would radiate it away. In other words, it is, as was stated, a slower process to cool the atmosphere than it is to heat it.
Atmosphere is heated by convection, and cooled by conduction. As the surface heats, convection increases. But at night, conduction is proportional to the difference in temperature between the surface and the atmosphere touching it. Slooooow…
Convection does not transfer energy from one substance (the surface) to another substance (the atmosphere), or vice versa, it moves energy around within the system because the atmosphere has had energy transferred to it from the surface. This produces instability in the atmosphere that must be resolved by mixing within the atmosphere. That transfer of energy to the atmosphere from the surface occurs through conduction or radiation – or some other mechanism I haven’t heard about. Convection is a major player that moves energy from place to place in the system but not the means of energy transfer between substances (molecules).
Ok, to be precise, it is conduction that actually heats the air at the surface. But from there on, it is convection that causes that heated air to rise. And, as it rises, air from somewhere else must move in to replace it. But that is hardly the point. The point is that the sun warms the surface rather quickly, but it cools off much more slowly. That is why summers are hotter than winters. It is also why the earth is warmer than its so-called black body temperature. It has absolutely nothing to do with back radiation or the so-called greenhouse effect. zero.
That would be true if the atmosphere directly absorbed long-wave IR (8µm to 14µm) from the Sun. If you look at the attached spectrum plots, you will see that incoming solar IR is mostly < 4µm.
This short-wave IR is not absorbed much by the atmosphere but is readily absorbed at the surface and tends to heat the surface. A non-linear transformation occurs whereby the Earth radiates its own “black-body” spectrum. This outgoing radiation has a longer wavelength, on the order of 10µm, which is much more absorbed by the atmosphere than 4µm IR.
Nitrogen, as you claim, does not absorb IR, but CO2 does. So it “traps” more earthshine than nitrogen (in the same sense that trap in your kitchen sink tends to “trap” certain items (air, diamond rings etc) but passes other (water) rather freely).
Huh? If the whole atmosphere were nitrogen, ALL of the incident energy from the sun would hit the surface and heat it. All wavelengths.
And no, CO2 does not ‘trap’ anything. CO2 is CONSTANTLY emitting, but it is NOT constantly absorbing radiation. A CO2 molecule can gain energy either by absorption or collisions with more energetic molecules. CO2 is, in fact, a cooling influence, not a warming one. If there were no CO2, as in my scenario, there would be no radiation from the atmosphere, and thus the surface would have to be warmer in order to shed the day’s energy to space.
Perhaps I did not make myself clear that, in the absence of molecules with asymmetric structure (e.g. CO2, H2O) surface heat photons would no longer be absorbed by air molecules in the lower troposphere and, unless absorbed or scattered by dust or clouds, would be free to head out straight to outer space. This would certainly not cause the surface to heat up, because when heat leaves an object it cools.
You did not make anything clear, you simply muddied up what is actually true. I assume you realize that air warms up during the day. You walk around in it, and you have a thermometer that tells you what the temperature is. If you chart it over 24 hours you will see that it warms up quickly but cools off slowly. The WHOLE atmosphere that is warmed up each day has to be COOLED down that night. With no ghgs, that is done by conduction, alone. It cools from the surface up. Yes, emitted photons from the surface would go to space. No, the surface would not be cooled below what it is now. The surface would receive ALL of sun’s radiation, and have to radiate it all away, every day. BUT – that part that warmed the air by conduction and convection WOULD HAVE TO BE ACCOUNTED FOR. You can’t instantaneously cool a mass of air that does not radiate. It has to conduct its heat DOWN to the surface. That PREVENTS the surface from cooling much below the air temp at the surface. There is a constant feed of energy to the surface until the surface and the air above it are in equilibrium.
I think I did. Everything I said was true, even the part about about cooling by radiation. Why do you think they put cooling fins on electronic components?
Actually, air is a very poor conductor of heat. At best conduction can transport surface heat a few centimeters above the ground. Otherwise, radiation and convection account for almost all heat transport from the surface to the atmosphere and beyond.
You seem to be unaware that even though nitrogen does not absorb long-wave IR it does allow the surface to radiate freely to the atmosphere and beyond, which cools the surface because of the loss of heat energy by radiation.
CO2 does absorb long-wave IR, then re-radiates in all directions. A small amount of heat is reabsorbed by the surface, leaving it slightly warmer (not colder!) than it would be in a pure N2 atmosphere.
You still have not explained how the absence of CO2 cools the surface, as you originally claimed. That is what you need to explain more clearly, without any hand-waving please.
The thing you are missing is that the atmosphere is pumped full of thermal energy by the sun. That energy has to get back to the surface to be radiated away BY the surface. The process of cooling the atmosphere off at night is a much slower process than the sun heating it. If all of the sun’s ‘additional’ energy each day is not returned to the surface, it will result in warming. It doesn’t matter HOW much the surface radiates, the excess energy in the ATMOSPHERE has to move via conduction TO the surface, which is slow. Look at some weather balloon traces for morning and night.
As far as CO2 radiation – yes, CO2 radiates continuously. Half is earth directed, the other half is space directed. Since the CO2 radiates part of the day’s energy, the surface will not get as hot as with nitrogen only. That is cooling because you have gh gas radiating to space as well as the surface radiating to space.
You should talk about hand waving – you ignore everything I say and then blame me for not understanding it.
I am not ignoring everything you say. But it is a hand-waving word-salad because it does not explain this:
The surface gets all of its heat from solar flux F, which establishes a temperature T according to Stefan-Boltzmann:
F = εσT^4
If you increase the flux heat, the temperature goes up. Removing flux heat (by eliminating back-radiation) would reduce the temperature.
You acknowledge that CO2 radiates earth and warms the surface. But if we remove the back-radiation, you haven’t specifically explained your claim that it causes the surface to get even warmer.
Johanus, you wrote:
“The surface gets all of its heat from solar flux F, which establishes a temperature T according to Stefan-Boltzmann:
F = εσT^4″
While it is true that the surface temperature is a direct consequence of exposure to solar radiation (together with a small amount of heat conducted from the planetary core, a few nuclear reactions etc), your second half of your statement is false. The S-B law does not tell you what temperature you get for a given amount of “incoming power” (which isn’t how power works). Instead, it tells you what power transfer you will get (develop) from an object at temperature T and emissivity ε, if the environment (target of the power) is at 0 K.
So then you said “If you increase the flux heat, the temperature goes up”, but what you really meant to say was, if the temperature of object A increases, and A is hotter than B, and there is a radiative path between them, then, all other things being equal, the temperature of object B will also increase.
Then you said “Removing flux heat (by eliminating back-radiation) would reduce the temperature”, but it is pretty clear that you don’t know what either “flux heat” or “back radiation” mean. Heat is defined as a flow of energy, but energy will not flow from a colder object to a warmer one (which is what people call “back radiation” when they denote it in Watts). The atmosphere does, of course, emit radiant energy in all directions; but it does not “emit Watts” in all directions. That is nonsense.
small nit-pick. It isn’t half earth – half space. The higher the molecule the smaller the angle subtended by the earth.
With that hypothetical atmosphere the average radiation at the surface over 24 hours would be about 340 W/m^2. So an average temperature of maybe 220K, probably like the moon hotter during the day and much colder at night. By the way radiation is proportional to T^4 not T.
Nope, that’s where you are wrong. Almost everyone forgets that we have a heated atmosphere and it has to be cooled at night. That is a slow process, as it is done by CONDUCTION only, and that can only happen when the surface temp decreases to below air temp. (In the nitrogen atmosphere. If gh gases are present, they will HELP the atmosphere cool.)
Note I said at the surface. The Sahara desert reaches around 38ºC in daylight and drops to around -4ºC at night, that’s just due to the absence of moisture in the atmosphere, in the absence of CO2 (your postulate) it will drop further. That’s at the equator, it will be even worse at 40ºN for example.
The surface temperature in your case without water or CO2 and an albedo of 0 would be 278K.
No, it would not. When the sun shines, it heats the surface by radiation. The surface heats the air by conduction. When the sun is gone, the air has to cool, but it can only do so by conduction with a cooler surface, and that takes time. It is why you can see frost on grass when the temperature of the air is above 32F.
When the sun is gone the surface loses heat to space by radiation, in an atmosphere of N2 that would result in very rapid cooling. The heat contained in the atmosphere would be irrelevant because of the low heat capacity.
You could hardly be more wrong. The surface heats the AIR, most of which is already nitrogen. Thermometers measure the temperature of that air. We record that for decades. To say that it is immaterial is, frankly, idiotic. The heat that goes into the atmosphere HAS TO COME BACK OUT!!
“We can also consider the case of a vacuum pressure of 10 Torr, the equivalent of about 110,000 feet above sea level. In this case, about 60 mW of power is required to maintain the filament temperature, so the gas is still accounting for about 99.3% of heat transport with radiative and end losses only 0.7%. As one goes higher in altitude a larger proportion of the heat transport is attributable to radiation, and that is how all the heat eventually returns to space in the extreme upper atmosphere.”
I would like to point out that this description does not explain how the atmosphere’s emission of longwave radiation varies so much over time and location even though surface temperature varies far less. The physical altitude at, say, 10 torr would not vary all that much either. But the variation of emitter output is huge, depending on clouds and motion. This is plainly seen at this link for GOES East Band 16. A similar point could be made from the CERES hourly longwave data.
https://www.star.nesdis.noaa.gov/GOES/fulldisk_band.php?sat=G16&band=16&length=12
The radiance at 30C(yellow) on the brightness temperature scale is 10 times the radiance at -90C (white.)
So to me, something clearly seems amiss.
Rubbish.
The Pirani gauge is most interesting!
It is, but it is not an analog of the Earth and atmosphere.
Neither are the models,
Brilliant.
Such a simple device with its calibration curve provides indisputable evidence that the GHE does not play a role in the surface energy balance.
To determine the actual altitude (or pressure) where the radiation emission dominates over the sensible heat transport would require calibrating the instrument for the atmospheric gas composition at the altitude and having the body of the unit at the temperature of the atmosphere at that altitude. The body of the unit inside and out pained black to better represent the emissivity of ice.
The calibration curve for the instrument is in the range of room temperature, which is quite a bit warmer than the altitude of typical emission; say 240K. The radiant heat loss is a function of temperature difference to the 4th power, while the sensible heat loss will be a linear function of temperature difference.
There is no doubt that the sensible heat transport dominates at the surface over short wave radiation but the emission temperature is around 240 to 250K.
THe device actually provides a simple means of replicating the conditions throughout the atmospheric column. It is an important contribution to developing a physical model of the atmosphere.
I suspect there is little to no net sensible heat transport aloft. That kinetic energy is simply converted to potential energy at altitude and converted back to kinetic energy in descent. It will resemble the adiabatic profile. This eliminates a net sensible heat transport mechanism.
The warming mechanism at altitude can only be by condensation, creating a warmer radiating surface than there otherwise might have been. This dominates the environmental lapse rate. This latent heat transport in fluid flux does not appear until it is converted to sensible heat in condensation aloft. In so doing, it overcomes the adiabatic process. This is critical.
Most spectral plots of OLR wavenumber lines show dominant curve at 273K in addition to the surface curve. Globally averaged this represents a dominant atmospheric radiating height approximately 2.3km. Below which non-radiative heat transport dominates.
That is incorrect and your comment on the 273K proves my point. Most of the sensible heat transport is carried by the water vapour that explodes above the LFC during convective instability. The LFC over tropical oceans is around 5km and some water vapour makes it to 14km.
The tropical rainforests have the highest altitude of heat release with the tropical oceans not far behind.
Of course the dominant release is around 273K because the OLR comes from ice. But that is above 5km in the tropics. The fact that most of the OLR comes from ice makes my point that the OLR is coming from the latent heat of solidification occurring at 273K and cooler. The ice was formed from the water vapour that transported the sensible heat above the LFC.
ja. i mean sensible heat transport direct from surface. I definitely agree latent heat of vaporization is the primary net transport mode from surface to radiating height. It is transported in fluid flux to condense. I would not call it sensible heat until condensation occurs.
The entire ocean is condensate, in addition to that which occurs in the atmosphere. The process of condensation is king. The most important bit is that the condensed matter surfaces in atmosphere provide full spectrum radiators at height.
That might be true if the Earth’s surface was made up of metallic Platinum!
The Earth does not shed energy via convection or conduction (at least in any appreciable way). It only sheds energy via radiation.
So more radiative molecules means a cooler planet.
Just like a thicker sleeping bag causes you to warm the great outdoors less.
No, it only allows for a greater dT between your skin and the great outdoors. You warm it at exactly the same rate.
And greater dT increases turbulent instability resulting in enhanced fluid dynamic heat transport.
No, it reduces the dT. If that are not the case you would not stay warm. You are releasing less heat from your body, so less heat escapes.
Not thought through.
Your metabolism – i.e., the rate of heat transfer through your skin and respiration – is assumed to be constant w.r.t. this situation. So, since you can stay at the same comfortable skin temperature in colder weather with a thicker sleeping bag, your dT from your skin surface to the great outdoors increases. And since you’re not heating or cooling the rate of heat transfer to the great outdoors remains constant.
I would say it results in more efficient cooling of the planet. Not necessarily cooler, as that is dependent on additional factors.
The transmissivity of the atmosphere with increasing altitude and latitude increases faster than the temperature falls.
The fluid dynamic heat transport makes it so. The mixing of the condensing atmosphere enhances radiative emission.
Only in the upper atmosphere. On the way up there’s a lot going on. Heat transfer happens at the molecular level. There’s transfer of kinetic energy, emission of photons, absorption of photons, mass transport of heat via convection, and condensation. The heat leaves the upper atmosphere via radiation when it becomes the dominant mechanism.
This is not new, I have been writing about it on my blog newscats dot org for a long time. My thinking follows the logic of this article but I am using different numbers.
A step in the right direction, very good!!
The article suffers from two minor issues.
Otherwise indeed a novel perspective..
Minor?
Sarc
Interesting. Don’t know if Mr. Shula’s novel perspective is correct but it is worth considering. He has certainly stirred a hornets nest among the “experts” on the site. That at least has the benefit of getting everyone’s attention and advancing the discussion. I do like the simplicity of his perspective even if most here think it is simplistic. Climate is extremely complex but that doesn’t mean the final explanation of it is going to be.
God Himself could come down and explain to Democrats that there is no global warming and they would not change their actions one iota.
Democrats consider themselves to be God, or an even Higher Power.
God would not come with acceptable credentials. Who does this bum think he is?
You should vary the wording to be clearer that you are talking about the surface and lower atmosphere where the solar EMR is thermalised.
For example – Solar EMR reaches the surface and lower atmosphere at the speed of light where some is thermalised (predominently in the tropical regions) and the resultant heat is transported by convection at much lower speed through the ocean and atmosphere to eventually depart as long wave EMR high in the atmosphere.
Ocean time constants are as long at 2,000 years. The energy that goes into lifting water onto land as ice can be delayed more than 100k before it leaves. . Humans are using the solar energy stored in fossils that arrive millions of years ago. It takes about 25 days for the atmosphere over tropical oceans to reach thermal equilibrium with the surface. Hence the current delay between the surface in the Arabian Sea and Bay of Bengal reaching 30C well before the monsoon is established:
https://earth.nullschool.net/#current/ocean/surface/currents/overlay=sea_surface_temp/orthographic=-274.64,12.83,369/loc=85.910,6.536
The whole point of the Pirani gauge is to measure gas pressure by making the gas the means of heat transport. Thus, one tries to make radiation transport as small as possible, done by using a filament with a vanishingly small emissivity at IR wavelengths. To then conclude from this device that radiation is an unimportant transport mechanism on Earth is circular logic. Earth materials have emissivities that are all near 1.0, maybe some are 0.9 but most are above 0.95, and MODTRAN uses a value of 0.97.
The gauge is not an analog for Earth.
That is indeed the critical flaw in Mr. Shula’s thinking.
Thanks for this comment. I think your points are correct.
Indeed as I pointed out above the Pt wire used in the Pirani gauge and it’s emissivity is 0.05.
“We know that there are three mechanisms for transport of heat energy: conduction, convection, and radiation.”
__________________________________________
And latent heat – it’s right there in NASA’s Earth Energy Budget diagram.
Latent heat is not a transport phenomenon. Water vapor is transported with its latent heat of vaporization up to the cloud level by convection. After condensation, the latent heat is released and is transported further by conduction and convection until it is ultimately radiated to space.
Latent heat enhances the heat content of the buoyant gas that is transported by convection. Convection is still the transport mechanism.
WUWT does itself no favours by publishing such poor science as this. attmepting to refute one set of pseudoscience with anther set of pseudoscience beneftits no one.
When the facts are on your side using poor arguments and telling lies ruins your position. FOX news apparently doesn’t understand this simple concept.
I would partially agree, Leo, that posting it without any editorial comment runs the risk that a casual observer could mistake the ‘open forum policy’ for endorsement or advocacy. However, WUWT wisely understands that science advances by the falsification of wrong hypotheses.
True science has nothing to fear from the free expression of ideas. It is only the suppression of ideas that perpetuates error, i.e. The Science ™ meaning the politicized orthodoxy.
Many commenters here have pointed out the flaws in this essay. Oftentimes the refutation of error can illuminate truth more effectively than the mere exposition of truth.
As Willis has often pointed out, the strength of having loose oversight on what gets published leads to immediate peer review. That is, things get analyzed in almost real-time by many experts, not just two or three.
Citations are the best metric. If the work is new and useful, it will be used to advance the knowledge base in other papers. If it is bogus – bad units, bad statistics etc. – it will be politely ignored. There’s a recurring Simpson’s scene where Homer intones nonsensically, there’s a 15 second pregnant pause and Lisa tactfully changes the subject. Like that.
Probably have some eyes burnin’ here….
Seems to me there’s a giant hole in this argument.
Evaporation.
The author correctly states that the surface loses heat by conduction, convection, evaporation, and radiation. At that point, however, he just sets aside the loss of energy from the surface in the form of latent heat in evaporation.
I don’t see how you can do that. Evaporation is the second largest mode of heat loss from the surface. You can’t consider the rest of the losses in isolation to “prove” something.
This is particularly true because evaporation is basically a linear function of wind speed. And thunderstorms kick up winds around the base. This greatly increases evaporation, and this in turn makes the thunderstorm stronger.
None of that is captured by the Pirani gauge, which means that it is far, far from an analog of the Earth. To paraphrase Einstein, “Everything should be made as simple as possible, but no simpler.”
This author has made it simpler, and that doesn’t work.
Best to all,
w.
“At that point, however, he just sets aside the loss of energy from the surface in the form of latent heat in evaporation.”
_____________________________
I don’t know why 9th grade general science leaves out latent heat, but it does.
Bullshit. You must have slept through class.
They still teach 3 ways to transfer heat. Yes they have a nice demonstration to illustrate latent heat, but it’s still just three ways of transfer. That’s why T. E. Shula missed it.
You can Google “how is heat transferred” and page after page says:
Heat Transfer – Radiation, Convection And Conduction
Clearly, you don’t question your own thinking.
You should write a book called: ‘The Laws of Physics according to Steve Case’.
I could suggest some co-authors.
Because those are in fact the only TRANSPORT mechanisms. Latent heat (as well as sensible heat) are transported by those three mechanisms. There is just a confusion of semantics here.
Radiation and conduction transport only energy, while convection transports both mass and energy. Evaporation at a surface results in convection of water vapor which carries both the mass and the latent heat energy up to the clouds.
I’m not sure latent heat is a form of energy transport. The vapour is transported by convection and the condensation occurs through conduction.
Latent heat is NOT energy transport. It is phase conversion. The surface water was converted to water vapour via its latent heat of evaporation then convected away as water vapour – a gas..
I was trying to be polite.
Bullshit. (-:
“I’m not sure latent heat is a form of energy transport”
Not in it’s self, but it is part of the process ;
Latent heat has been locked in to the molecules during the phase change from liquid to vapour, that vapour is now lighter & is transported (say 20,000 ft) by convection to a place where the original conditions that formed the vapour don’t exist; so, another phase change occurs as the vapour loses some of its heat energy by radiation to other molecules in the new place until they reach equilibrium.
That original heat energy has now been transported 20,000 ft.
“condensation occurs through conduction.”
Yes it can … as in a plate condenser;
but also occurs with
change in pressure / temperature … as in vapour trail from a plane wing
Latent heat and evaporation are not transport mechanisms and Shula ignores the importance of latent heat of evaporation in the convection transport.
Both are true.
At that point, however, he just sets aside the loss of energy from the surface in the form of latent heat in evaporation.
No he doesn’t. The latent heat is manifested in the form of water vapour. It was surface water that was converted to gas. It is then carried off through convection. He is not excluding latent heat.
Seems to me you completely missed the point of his article, Willis. He told you the same thing that I and many others have been telling you for years, which is that those downwelling infrared Watts are all fake, and this statement of physics is easy to verify experimentally. But you didn’t object to that point when he said it, for some reason. Nor did you respond with your standard “Pass!” or “Bovine excrement!” Instead, you misinterpreted his point and claimed that he had forgotten about evaporation (which, as others have pointed out, I don’t believe he forgot at all). Do you agree with him that the downwelling longwave Watts are fake, then?
Are you saying that temperature plays no role? It seems to me that wind plays two roles: 1) it can supply kinetic energy (KE) to strip molecules off the water surface, wherein the KE of the wind varies with the square of the velocity; 2) wind removes an air film that is saturated with water vapor, thus reducing the partial pressure of water vapor and encouraging the phase change because of the KE of the water molecules, which increases with temperature. Certainly a pond of water in a hot desert, even without wind, will evaporate much more quickly in the Summer than in the Winter.
Build yourself a spreadsheet.
Imagine a spherical blob of water with circumference of 40,000km
No atmosphere
No land, all water and water that never freezes
Rotating once in 24 hours
Have a sun shining on it at 1,372 Watts/square metre
Water works for this because it absorbs immense amounts of energy through its depth (100 metres?) but can only lose that energy from its surface ##
Over the course of 24 hours, its temperature will not change very much – although that is a correction you may want to add
Allow the water an Albedo (normal incidence) of 0.06
Give the water an emissivity of 0.95
(This is the Joy of Spreadsheet, you can change those things and see what happens)
Calculate the total energy absorbed on 1 square metre wide strip around the equator inside 12 hours
The average power will be the RMS of a sinewave =1372 divided by squareroot(2)
Calculate that to be in temperature equilibrium, that water must lose all the energy it absorbed inside 12 hours over all 24 hours of the day.
So what temperature will it be?
How big is that area of temperature?
Then, consider your water globe to be divided into (your choice how wide) strips of latitude of 5 degrees
Use the cosine(latitude) to get a new Peak power, a new average power, an new temperature , new area and a new TempxArea
Repeat until you get to 85 degrees latitude.
Sum all the TempxArea and divide by the total area.
iow: Do a proper temperature area integral
I got a value of 10.4°Celsius for the whole globe
Especial highlights being:
Temp of equator = 88°C
Temp at 30° Latitude= 75°C
Temp at 60° Latitude= 30°C
Temp at 85° Latitude = -77°C
Temp got to near freezing (3°C) at 70° of Latitude)
Reconcile that with what you’re told, what the authorities you’re appealing to have to say and what you know of The Real World.
esp Why isn’t the temperature of deep water at the equator = 88 Celsius
Does ‘radiation’ and GreenHouseGas cause the real equator to be cooler than we calculate and the real poles to be warmer?
What might explain the immense difference we see (88°C vs 31°C) of equatorial water?
Oh you say, “Clouds and evaporation do that”
Thank you – you just trashed the GHGE – radiation is minute, trivial and irrelevant in its effect.
## See the Fatal Flaw in all calculations of ‘initial’ global temperature…
i.e. They don’t do a proper integral of temp and how big an area ‘has’ that temperature and they make no allowance for the fact that water stores energy
Play with the spreadsheet – see how insanely sensitive it is not only to Albedo but also Emissivity
That convection and evaporation does most of the work is not a refutation that ‘trashes the GHGE’ any more than noting that most people are 150-200 cm tall makes talk of Pygmies pseudoscientific claptrap.
You forgot to mention sugar and soil erosion, Peta. You’re slipping.
The tricky bit is that it’s the reduced LW transmissivity due to the IR active gases which kicks off the fluid dynamic heat transport. They cannot be separated.
All process of evaporation, conduction, and whathaveyou are encompassed by the fluid dynamic mass flux (convection).
It is the resulting fluid dynamic heat transport associated with mass flux which dominates the energetics of the atmosphere.
This is initiated by anomalous warmth near the surface causing instability. The degree of instability is governed by the difference between the virtual adiabatic lapse rate and the real environmental one.
These maintain a dynamic instability factor of 3:2. Therefore, globally averaged anomalous near-surface boundary layer warmth is strictly bound to the solar absorbed and/or that radiated from the top.
The tangible and latent heat goes along for the ride. This fluid dynamic transport diffuses the heat throughout the system in such a way as to minimize temperature (optimize radiative emission).
The observable near surface atmospheric absorbed energy is strictly bound to 1.5x OLR. This is enforced by the instability factor 3:2.
Anomalous Earth Energy Imbalance is always occurring by excess (or deficits) of solar absorbed into ocean.
In the case of excess solar absorbed SW into ocean, the boundary layer atmospheric instability and OLR will have no awareness and will not respond until such a time as it presents itself in sea surface temperature.
I have some problems with this article. First, logarithmic scale does not have a zero, so the bottom value on the Y axis in the diagram should have been 0.001. Secondly, it is sad and at the same time annoying, when an article describing science, has elementary errors, like “200 milliTorr (0.02 Torr)”. 0.02 Torr is 20 miliTorr, 200 milliTor is 0.2 Tor. And yes, 0.2 or 0.02, as the leading zeroes should be included, as you have it correctly only 3 lines above “0.7%”.
Thank you for pointing out the typographic errors. Yes, it should be 20 millitorr, not 200 millitorr. Regarding the y-axis zero, I believe in the formatting of the chart the “1” in “0.001” was cut off. I am using the chart with the permission of the owner and cannot make any changes.
Tom,
I find the use of the non-standard Torr as a unit of pressure to be unhelpful. ( I am being polite).
I had to look it up. Wiki says this about the Torr
Here is a converter that gets us back to Pascals.
Thank you for being polite, Phillip. Perhaps I am a bit old school. I worked in the vacuum equipment industry or with equipment made by it from the late 1970s onward into the 21st century, and in North and South America, Europe, and Asia all of measurement equipment reported vacuum in units of torr or fractions thereof. Also, the chart which MKS Instruments kindly granted permission for me to use also uses torr as pressure units and I cannot modify it.
My apologies for your inconvenience. Thankfully, the converter is available if you can only work with Pascals.
Noted.
You stretched my brain at 3 am in the morning. Not a good time for a work out. 😉
This is not analogous to the earth.
For a better comparison, the walls of the device would have to be cooled to nearly absolute zero. If the walls are at ambient temperature, they will be radiating almost as much energy back to the wire, as the wire is radiating to the walls.
R
The walls should be painted black inside and out as well to more closely represent the emissivity of ice, which is the most common radiating surface for OLR emissions.
So paint the device inside and outside black. Produce a range of calibration curves for different external temperature and corresponding gas mixture for that temperature (altitude). and then determine where the sensible heat transport gets overtaken by the radiation transfer. It should correspond to about 240K.
Thomas E. Shula
You didn’t tell us what the constant temperature was of the filament. It makes a difference because the radiation loss you measured is the NET radiation loss. It is the sum of the energy radiated from the filament minus the radiation absorbed by the filament from the environment. What was the temperature difference between the filament and the walls of the container? Was the inside wall of the instrument made of absorbing material?
Good article Thomas, and I’m glad someone is pointing out NASA’s errors. Very few people seem to realize that the standard form of the S-B law includes the assumption that the environment is at absolute 0. Thus, the only way to produce those hundreds of Watts per square meter of “downwelling longwave infrared power” at the surface, is if the surface temperature is also at 0 K. MODTRAN will show you this, correctly (although unfortunately it does not let you set the actual surface temperature to anything higher than 0 K, as far as I can tell).
You could make the same point with the SURFRAD pyrgeometers, and point out that the measurements of downwelling LWIR power at the surface at ambient temperature are all negative. The only way they can report positive numbers is by abusing that S-B law and making up fake power, assuming again that the environment is at 0 K when it is nothing of the sort.
I have some theories about why the “radiationists” went off the rails back in the 1950s and 1960s, and even back then Strong and Plass were warning us about not getting too carried away with radiative energy transport, and to remember to take the other forms into account. But no one listened…
Steve,
The back-radiation loop that returns energy to the ground in the standard radiation diagram of climate is in fact the adiabatic convection loop of meteorology hidden in plain sight.
See Figure 3 The Atmospheric Reservoir Energy Recycling Process
p.s.
Starting with K&T 1997 Fig 7 they show all the atmospheric dust absorption of insolation of 67 W/m2 to be at the top of the atmosphere and the surface reflectance to be 30 W/m2. . The surface absorption is 168 W/m2, so the surface absorptance is 0.848 with a corresponding reflectance of 0.152. This surface reflectance is part of the Bond Albedo. So they have no boundary layer quenching of surface backlighting.
Our Mars study shows that this is nonsense, there must be surface boundary layer quenching on the Earth too.
I found a very good paper on Research Gate that gives the global surface reflectance as being between 0.2 and 0.3 so the K&T value of 0.152 is wrong.
pps The beautiful pastel red post-sunset sky last evening here in Nottinghamshire, with its low-level over the horizon illumination of the dust in the surface boundary layer was stunning.
Hi Philip, are you saying that because the atmosphere maintains a thermal gradient under gravitational pressure (together with convection etc), NASA is “effectively” correct when they draw arrows with hundreds of Watts per square meter of downwelling radiant power? These two phenomena do not look identical to me.
fantasized AGW
as hot molecules go up the pressure they are exposed to drops off which means they “cool” without a drop in specific energy… not understanding actual physics is what causes “global warming” like how mercury thermometers take longer to cool than heat and how thermistors have to be double-adjusted and placed VERY carefully and take humidity into account to produce an actual temp reading
So many different opinions as to how our climate warms, I am totally lost.
Let me ask this.
Whenever there is an El Nino in the Pacific ENSO area, global temperatures always rise.
What is the mechanism for the global temperature increase?
That is outside the the purview of this topic, but in a nutshell El Niño is characterized by an upwelling of warmer water in the Pacific Ocean off the west coast of South America. La Ninã is the opposite when the surface temperatures are colder than average.
This is a good explanation of how a Pirani gauge works. They are very useful and I’ve used them for decades. They are great for telling you if you can spin up your turbo pump. They’re not precision instruments, though, and their readings depend on the gas species in the system. If you want accuracy in this pressure range, you go with something like a capacitive manometer (also made by MKS).
One thing that worries me about the analogy being employed: I’ve never operated a Pirani where one side of it is held at ~288K and the other at just a few degrees K. Just sayin’.
But with a few modifications the device could be used to establish the transition point in the atmosphere where radiation begins to dominate sensible heat transport.
-Paint inside and outside black to Peter represent the emissivity of ice..
-Make temperature difference between filament and body say 250K but over a range – ideally temperatures similar to the atmosphere so the body very cold.
-Produce calibration curves over a range of body temperature for saturated air rather than just N2.
The Pirani gauge offers a simple method to make meaningful experiments of atmospheric heat transport processes representative at different altitudes.
They got it so wrong because it was never about temperatures in the first place. In the 20th century, paleontologists found that life was most abundant and varied with temperatures 2-4 degrees C above present.
It was about power and control–and about causing the extinction of Life on Earth in all its forms from humans, pets, mammals, reptiles, amphibians down to fish, trees, flowers, mosses, grasses fungi, bacteria.
All life on land depends on photosynthesis: CO2 + H2O + sunshine in a green plant —> sugar and O2. Because we need air so urgently, the oxygen is described as the product of photosynthesis. Because our schoolteachers are the dumbest people who can still graduate from college, most Americans and other earthlings are innumerate and cannot reason with one O2 per CO2 in 0.04% CO2 versus about 20-21% oxygen and how much difference photosynthesis really makes. I expect some WUWT readers will now do the math since I have called your attention to it.
From the sugar, plants make all the rest of their bodies, which herbivores and omnivores eat. Food. They are trying to starve us all to death.
Story Tip
There have been a number of comments/questions regarding the Pirani gauge. Rather than addressing each individually I will attempt explain in more detail here how the heated element in the Pirani gauge serves as a proxy for the surface of the Earth in my exposition. Most of the concepts involved are in the Appendix section of my paper. Also, for reference I will use the chart of the Pirani gauge response. Finally, the Pirani gauge is designed to measure vacuum in a limited range of pressures. There are other devices that operate outside those ranges in applications that need them. We are not concerned with the precision of the gauge. It’s value in this exposition is its principle of operation and ability to directly measure the relative contributions of radiation vs. conduction/convection to heat transport in a gaseous environment.
Let’s start with the Pirani gauge in a state with a near perfect vacuum in its enclosure. If calibrated as the device represented in the response graph, the controller will provide a current that heats the filament to a specific temperature, in this case the power dissipation is 0.4 milliwatts. That power represents the radiation loss from the filament as well as other losses from junction heating, etc. and may heat the enclosure slightly. At steady state this does not matter, because irrespective of the size of the enclosure the temperature of the filament will remain constant.
In this state, the filament can be expected to emit radiation according to a modified Stefan Boltzmann Law based on its temperature and (typically low by design) emissivity. In this case there is a spontaneous emission of photons from the filament that balances the power input (0.4 mw) from the power supply.
Now, let’s introduce some air into the enclosure. We need to look at what is happening at the boundary layer at the filament/air interface. As soon as the gas molecules are introduced, they begin colliding with the filament. Three things happen: 1. Some of the colliding gas molecules pick up energy from the filament at a higher temperature. 2. Removal of the energy from the filament by 1 lowers the temperature of the filament. 3. As a result of 1 and 2, the frequency and average energy of photon emission by the filament is reduced. It is at this atomic level at the boundary where the heat transport begins, and where nature decides the balance.
The gauge controller responds by increasing the power to the filament until it returns to the original temperature, but now in a gaseous environment rather than a vacuum. The additional power is providing a continuous influx of heat capacity (remember this concept) that exactly balances the heat energy that the gas molecules receive from the filament. We know the power input required to maintain temperature under vacuum, and we know the power input required to maintain temperature at pressure. The difference between those two is the power that is being removed by the gas via conduction/convection.
Note that so far there has been no need to take into account enclosure size, enclosure finish/emissivity, filament emissivity, or specific temperature. These can change sensitivity, precision, range, and other operating characteristics of a specific gauge, but the operating PRINCIPLE remains the same. In determining heat transport between a solid surface and a gas, it’s what happens at the boundary layer that counts. There is one requirement: the temperature of the filament must be higher than the temperature of the gas, otherwise there would be no net energy transfer from the filament to the gas.
If we are going to consider a particular pressure regime, we might as well look at atmospheric pressure at sea level since that’s the place of interest in this exposition. What is the boundary layer at the surface? At atmospheric pressure the molecular mean free path is about 70 nanometers, and the collision rate with a planar surface is about 3 X 1027 collisions/m2-sec. As in the Pirani gauge, conduction at the surface is what triggers heat transport and creates convection. The rate of conduction is proportional to the difference of temperature between the surface and the gas, and INVERSELY proportional to the thickness of the boundary layer. With a mean free path of 70 nm the boundary layer thickness is extremely small, so even a small temperature difference can produce efficient conduction. It also perturbs the radiation output negatively. In the case of a large temperature difference, for example pavement on a very hot day, we can actually see a “mirage” in the distance due to the large lower density convective layer at the surface refracting the sunlight. For smaller temperature differences, it may not be that striking but convection is still occurring. The surface temperature is almost always higher than the air temperature above it. A layman’s explanation of why this occurs in soil can be found at:
https://accessiblegardens.org/soil-temperature-why-its-hotter-than-air-temperature/#:~:text=The%20majority%20of%20soil%20temperatures%20are%20lower%20than,can%20hold%20onto%20it%20for%20a%20long%20time.
Relative to air, the surface of the Earth whether land or water has a tremendous heat capacity, which is why this has a small effect on the temperature of the surface. This is all that is necessary to demonstrate that the principle of the Pirani gauge applies to the (land) surface of the Earth.
The heating of the surface is from incoming solar radiation. As the solar radiation wanes, the surface will cool, and so the air will cool as well, typically at a faster rate than the surface. The diurnal cycle is dynamic, and it changes throughout the day.
In the case of a water surface (extremely important so not to neglect it) evaporation is occurring on a more or less continuous basis which results in convective transport as well.
Nature has priorities. Flowing water will follow the most efficient path driven by gravity. If something gets in the way, it will go around it or annihilate it. Heat will follow the most efficient path driven by temperature differences. Radiation is natures last resort, when there is no physical medium to transport the heat. When the options of conduction or convection are available, they will always win.
I hope this has been helpful.
“In this state, the filament can be expected to emit radiation according to a modified Stefan Boltzmann Law based on its temperature and (typically low by design) emissivity.”
Which is why the Pirani gauge is not a relevant model for the Earth as the earth’s surface has a near black-body emissivity as has been pointed out to you several times in the comments. If you wanted a Pirani gauge to simulate the Earth’s surface you’d need to have the element coated with platinum black, but then the results would be much different.
If we were looking at the Earth from the Moon or Mars, we could look at it as a modified black body because the only energy transport we would detect would be radiation. That’s not what we’re doing here.
It is invalid to treat the SURFACE of the Earth as a black body. It is enveloped in an atmosphere, and that changes the energy transport dynamics completely. That is what is demonstrated here.
It is not invalid to do so, the surface of the Earth radiates depending on its temperature and emissivity and is close to a true blackbody (averages about 0.95). The energy transport dynamics of the Earth’s surface are dominated by radiation. Your comparison with a Pirani gauge is invalid because the wire in the gauge is deliberately chosen to have an emissivity close to zero (0.05) so that conduction and convection dominate. The atmosphere does effect the energy transport dynamics to space, it’s known as the Greenhouse effect due to IR absorbing gases such as CO2, O3 and water vapor.
Layperson question: If heat transport dynamics are dominated by IR radiation vs air, 95% IR per the NASA energy budget illustration, doesn’t that mean hot water in a vacuum flask, that is limited to IR transport through the vacuum (aside from conduction losses thru the flask materials), would cool down hot water almost as fast as hot water in an un-insulated container? And if the Pirani gauge element had an emissivity 20 times higher than the the one it’s made with to match earth, are you saying the Gauge result would flip from <1% IR/99%gas, to 5% gas/95% IR?
That’s why the vacuum flask is coated with a reflective material, to reduce any radiative losses. Yes the increased emissivity would have the effect you suggest.
Vacuum coffee mugs like those Contigo driving containers Costco sells have no reflective coatings, just a vacuum between two dull stainless steel walls. They work pretty much as well as a glass vacuum flask (surface temp on the side wall is only a degree or two warmer than ambient with boiling water in it), except for higher conduction losses though the large plastic lid. Reflective emergency blankets can block the IR emissions from a human body, but only if there is an air a gap, and so can a canvas tarp https://www.youtube.com/watch?v=97l5xvslmsg. So I’m not buying that. It’s clearly the gap with no gasses in it that makes a vacuum flask work at all.
On the emissivity, my gut tells me the difference between .05 and .95 might change the ratio from <1% IR/99% gas, to maybe, 5%IR/95% gas or even 10%IR/90% gas, but not completely flip to 95% IR and 5% gas, as the models require. This makes no sense whatsoever. The engine on my airplane has a cooling plenum in the cowling and baffles designed to force air *between* the cooling fins on the cylinders at maximum velocity in flight to properly cool the engine. All it takes is a baffle that’s not positioned correctly, allowing air to get around the fins instead of between them, and there will be damaging local hot spots. If the majority of heat rejection from an object was IR, per the climate models, this would be completely unnecessary. People paint cylinders and heat exchangers flat black, emissitivity of .98, hoping to improve engine cooling, and it makes no difference whatsoever. Aircraft engine manufacturers paint them gloss grey b/c the paint is just for corrosion protection. Clearly 99% of cooling IS conduction/convection.
In that vein, this guy demolishes the whole IR vs cond/conv battle as it applies to autmotive heat exchangers. Examples of Tom’s Pirani Gauge comparison are all around us all the time. I’m really thinking this is a King Has No Clothes moment and we’ve been sold a completely false paradigm. It’s Saturated Fat Clogs Arteries all over again.
Unlike the presenter of your video I taught Thermo. at university to both undergrad and grad students and ran a world class combustion engine lab. The engine cylinder walls are heated by radiation and convection from the flame, that heat is then transferred by conduction through the walls. Heat loss to the outside is then by radiation and convection, in order to increase the heat loss forced convection is used which is increased by greatly increasing the surface area by adding fins and increasing the air velocity across them. Since the radiation surface area isn’t increased the radiation loss doesn’t increase, in fact it decreases because the surface temperature decreases and radiation heat loss depends on T^4. There is no resemblance to the Pirani gauge.
Vacuum flasks don’t actually work very well at near boiling water conditions, they’re much more efficient for cold materials. I used to use them in the lab for storing liquid nitrogen, under those conditions the reflective coatings are very useful.
As far as your ‘gut’ is concerned about radiational heat loss, it’s wrong.
This is very unconvincing. If IR was the majority of the heat loss, you wouldn’t need fins. You have to address that.
Even if the radiation is the majority of the unenhanced heat loss it isn’t enough. The easiest component to increase is via forced convection: increasing the area and also the velocity of the cooling gas. For larger engines that doesn’t work too well and then liquid cooling is used.
For heat sinks forced convection set more than 95% of heat losses and 70% for natural convection. IR heaters dont heat the air, even If they emitt more 15um radiation than Earth surface according to Planck Law. Radiation is a nothingburger in relation to surface – air heat transfer. Heat capacity is as oceans dont radiate at 120C aka 1380wm2 in equator at noon like on the Moon. Oceans store a huge heat that they release slowly. Ground surface too. Thats why even during 30 days long Moon night, T surface stay at 100K and never reach 3K. If Moon had same daynight cycle duration than Earth, its Equator mean T would be higher than Earth Equator. GHG emitt less wm2 at higher altitudes cause work is done by air parcel aka kinetic energy is lost. This fact dont show heat trapping but work done.
M, m, and I, Thanks for chiming in. I agree wholeheartedly. I am grateful to those participants in this discussion who both have an open mind and can look at the big picture.
One of the things I have come to understand in this discussion is that most invoked in the mainstream debate have only looked at the process through the lens of radiation. They are ignoring what is happening at the boundary layer at the atomic level where the atmosphere meets the surface. The mean free path of an air molecule at STP is only 70nm, so there’s a lot going on in the first micron or so of air where it meets a terrestrial surface.
Which is why a vacuum bottle works. Can you post a link to the table?
The largest aircraft engines, approaching 4000 hp, were air cooled. You use liquid cooling because it’s easier to manage temperature and if you want to use an inline engine for the lower frontal area, air cooling works very poorly because of air distribution issues.
You’re implying that convection is only needed to achieve a marginal requirement, which you have to do to defend the climate model assertion that 95% of heat is rejected by IR emission in the lower atmosphere. I don’t need to build an elaborate forced air cooling system with fins to cope with a 5% requirement. I do when it’s a 95% requirement. Again, this makes no sense If convection is only 5% of heat transport in the lower atmosphere.
The difference is that at the Earth’s surface the difference in temperature between the surface and the air is small which gives low convection. In the engine case there’s a much higher temperature difference driving convection. Convection is the process which can be significantly enhanced by forcing the coolant at a high velocity and increasing the contact area (fins).
Phil, I’ll agree with your vacuum flask comment. Vacuum flasks are more efficient at keeping cold things cold that hot things hot. But they do slow down heat transfer in both directions. I appreciate that every day as I can enjoy a big thermal mug of hot coffee over a couple of hours while my iced drink in the same container will maintain ice in it all day.
I also agree that the radiator for your ICE has little in common with the Pirani gauge. I have to ask the question, if you think radiative loss is more important, why do you think radiators are designed to increase convection rather than increase radiation?
I don’t “think radiation is more important”, in certain circumstances it can dominate in others not.
Regardless, if IR transport is 95% and convection/conduction only 5% in the lower atmosphere, as the climate models claim, a vacuum flask will transport nearly all the differential heat, in or out, by IR radiation through the vacuum gap,independent of atmospheric pressure, and it will work no better than a pop bottle. There is a giant logical gap here.
That’s why the walls of the vacuum gap are coated with a reflective surface.
Oops forgot the second link https://www.youtube.com/watch?v=z_mmmXTbLP0
Tom, is it fair to say, for a layperson, that if the IR radiation dominance hypothesis underpinning the Greenhouse Effect was true, a vacuum thermos wouldn’t work (because the vacumm in the bottle would serve no purpose and if anything coffee would cool down faster than just in the open air), air cooled engines could be cooled just as well without blowing air on them since almost all the heat rejection off the cooling fins is IR? A whole range of practical effects that are blindingly obvious in everyday life?
Sorry I missed your earlier comment in the previous thread. I see that Phil replied regarding the reflective coating, and that is true. The more important characteristic of the vacuum bottle, however, is that the vacuum between the double walls of the thermos stops convection which is the dominant mode of heat transfer at atmospheric pressure. Your analogy regarding air cooled engines is a good one as well. If radiation was dominant, there would be less need to blow air over the cooling fins.
When you go outside on a cold day in short sleeves, your arms don’t get cold because you are radiating more (your body temperature hasn’t changed), your arms feel cold because the cold air is conducting heat away from your body and it’s carried away by convection. Cover your arms, and you don’t get cold so quickly.
Another good example is double pane windows. They don’t necessarily stop radiation, but they do reduce conduction and convection by a considerable amount.
Suggestion! Can you take a Pirani Gauge and paint the element flat black to raise its emissivity to around earth’s and do some measurements for comparison? You have to find a way to put that counter argument to bed. Or, some engineering guy at the manufacturer should be able to provide data on how much the measurements would change with an element with .95 emissivity.
The Pirani gauge with the wire at 60ºC would radiate ~650W/m^2K with an emissivity of 0.95 only ~35W/m^2K with 0.05 as designed. Such a wire in atmospheric pressure air at 20ºC will lose ~400W/m^2K via natural convection, that will be lower at lower pressures.
Phil, you don’t seem to understand that the emissivity of the sensor is irrelevant, because the radiative loss in the Pirani gauge is a constant, not a variable. A low emissivity sensor is chosen to improve the sensitivity/SNR. That does not change the operating principle.
You only look at the world through the lens of radiation. That is why you cannot see this. If you had experience in applications where you actually see heat transport in action, you would understand that radiation is nature’s last resort. It takes over when conduction/convection is not available or saturated.
The emissivity of the sensor is not important in the operation of the sensor but is chosen to be low to ensure that convection is the dominant process. The only reason I brought it up is your claim that “The filament in the Pirani gauge is analogous to the surface of the Earth”, which is not true because of the major difference in emissivity in the two cases.
I don’t “look at the world through the lens of radiation”. I have considerable experience in applications involving heat transfer, radiation is not the “last resort” it is present all the time, boundary conditions determine the relative importance of different mechanisms.
A person standing in a room maintained at 22°C at all times. The inner surfaces of the walls, floors, and the ceiling of the house are observed to be at an average temperature of 10°C in winter and 25°C in summer. The rate of radiation heat transfer between this person and the surrounding surfaces if the exposed surface area and the average outer surface temperature of the person are 1.4 m2 and 30°C, respectively and the emissivity of a person is 0.95.
Q=154W in winter and 40W in summer.
The experimentally determined convection heat transfer coefficient from a person is ~6 W/m2·°C so the heat loss by convection is ~67W.
You are assuming again that the radiative transfer dominates. How do you calculate the convective heat loss? What was the experimental methodology used to determine the number you present?
No assumption, just calculating using measured quantities. Convective heat loss = hA(T1-T2)
The human body generates roughly 90-110W of total energy, so based on your example, convection is roughly 70% and IR is 30% in the lower atmosphere. But climate models assume roughly 95% IR and 5% convection. So even if I accept those values, how do you go from 30% to 95% IR, and 70% to 5% kinetic gas transfer? The climate models are way off, based on your own example, right?
No, you don’t appear to understand that the losses depend on the boundary conditions. For example in the winter condition calculated the losses are Radiation 154W, convection 67W, increase the wall temperature by 15ºC and it becomes 40W and 67W.
However the Earth surface isn’t at 30ºC surrounded by a wall at 10ºC!
Just to be clear, do you assert that if the Pirani Gauge had an element with an emissivity of .95, the ratio of kinetic transfer would completely flip, from <1% IR/99% convection/conduction with .05 emissivity, to 95% IR and only 5% convection/conduction, as the climate models claim, with a .95 emissivity element?
Back to my coffee vacuum mug. The liner is dull SS, not a mirror and in any case the liner becomes heat soaked with the hot water by conduction, so even if there’s a mirror finish it’s going to emit IR across the vacuum gap from the back of the mirror anyway, to the outer wall, being heat soaked from conduction, and the outher wall has no reflective surface, just dull SS, so it’s going to absorb most of the IR. The outer wall should get warm if IR is so dominant. Yet it stays within a couple degrees from ambient down the barrel away from the lid, with the lid area that is conducting heat to the outside through its plastic, is about 40C.