Our Greenhouse

The Greenhouse and its Effects (PDF) was originally written in 2011 by Dr Vincent Gray, expert reviewer of UN-IPCC Assessment Reports.thegreenhouse

This page provides a few salient extracts from the full PDF, a copy of which is provided here for convenience in case the original location becomes invalid.

Abstract

The climate of the earth is said to be controlled by a mechanism called “The Greenhouse Effect” named because of its resemblance to the action of a greenhouse, which is supposed to cause a warming effect on its contents. Yet what actually happens in a greenhouse is imperfectly understood, and its influence on our climate confused.

This article surveys the history of attempts to explain the action of a greenhouse and its relationship to our climate. It provides an improved explanation of the behaviour of a greenhouse which applies also to the behaviour of the climate.

The so-called pioneers, Fourier, Pouillet, and Tyndall, believed that the earth was warmed by absorption of the sun’s ray by the atmosphere. Tyndall thought that this absorption was by water vapour. Arrhenius, who first claimed warming was caused by atmospheric absorption of radiation from the earth, claimed it was caused by carbon dioxide but he actually measured water vapour. Callendar, who revived the Arrhenius theory, firmly blamed carbon dioxide and ignored expert opinion that he had omitted the influence of air movement.

R W Wood showed that the air in a greenhouse is warmed by convection but failed to notice that this also implies cooling the earth, and that this only in happens when the sun shines. When the sun does not shine, the previously warmed air helps to reduce cooling.

A greenhouse protects its contents from outside weather, and by convective and water vapour evaporation cooling when the sun shines, and mitigation of cooling when the sun does not shine. Similar mechanisms dominate the climate. Human influences such as weather protection and reduction of convection and water evaporation/deposition would cause warming.

Current computer models are shown to ignore the difference between day and night, and to place too much emphasis on radiation. Their calculations show that changes in convection and evaporation/deposition of water vapour, caused either by natural or human action are far more plausible reasons for changes in climate than increases in minor trace gases.

It should be noted that the original publication was referred to in Dr Gray’s castigating review comments of the drafts of the UN-IPCC’s 5th Assessment Report which should be perused at leisure.

Robert Williams Wood (1868 – 1955) was an American
physicist and inventor. He wrote a standard textbook on
“Physical Optics. …

The following article was published in the Philosophical Magazine in 1909:

The solar rays penetrate the atmosphere, warm the ground which in turn warms the atmosphere by contact and by convection currents. The heat received is thus stored up in the atmosphere, remaining there on account of the very low radiating power of a gas. It seems to me very doubtful if the atmosphere is warmed to any great extent by absorbing the radiation from the ground, even under the most favourable conditions.

I do not pretend to have gone very deeply into the matter, and publish this note merely to draw attention to the fact that trapped radiation appears to play but a very small part in the actual cases with which we are familiar.

And so onto the

THEORY OF THE GREENHOUSE

A greenhouse has, as a main function, the protection of the interior from loss of heat absorbed from the sun by the outside weather, from wind, and rain.

When the sun is shining, its radiation passes through any panes of glass with minimal absorption and is absorbed, mainly by the base, where plants are present, but also by any part of the structure it encounters, raising their temperature.

The air within the greenhouse which is in contact with any heated surface receives heat by conduction. As heated air becomes lighter, it rises, and is replaced by cooler air. The warmer air rises to the surface but cannot leave, until the entire greenhouse has become warmer than the air outside the greenhouse. This process is called convection and it cools the surfaces that have been heated by the sun to a temperature which is almost uniform, but is higher than the outside climate

This fact; that when the sun shines the air in the greenhouse cools the heated greenhouse base and walls, was not appreciated by any of the pioneers mentioned above and it is not mentioned by Wood. Everybody, including Wood, seems to forget that if the air in a greenhouse is heated by convection from the heated base and sides, it is therefore carrying out a cooling function. Also, none of them mention that for any water or moist surface the sun’s rays will evaporate water, and this will also cool the heated surface and establish a moist atmosphere.

All the surfaces, both external and internal, as well as the air inside, will radiate in the infrared according to their temperature but as Wood believed, this is probably small. All the internal radiation will be absorbed by the sides and roof. The entire structure will largely be cooled from outside by external convection and radiation.

Nobody seems to have noticed it is all different at night, or even when the sun is not shining. Then, the loss of heat by radiation and convection by the whole structure and its contents is reduced by the heat which is stored by the interior air. In addition the extra moisture in the air is deposited, releasing latent heat.

We march, loaded with curiosity, to assail

THE REAL GREENHOUSE EFFECT

The real Greenhouse effect is the behaviour of the earth’s atmosphere in a similar way as in a greenhouse. The atmosphere is held in place by gravity, so the top of the troposphere performs a similar function as the glass ceiling of a greenhouse, as it prevents loss of air heated by convection. The sun’s rays are absorbed by the earth and if there were no atmosphere the temperature would rise to a higher level by day and fall to a lower level at night.

The average daytime temperature of the moon is 107°C and at night -153°C, but the time of rotation of the moon is 27 days, so the earth without an atmosphere would not reach such extreme values. However, the temperature would be much higher during the day and lower at night if it were not for the atmosphere.

The atmosphere in contact with the surface removes heat by convection so that, to start with, its temperature is similar. Its temperature steadily falls with height as it is radiating all the time, some returning to the earth. It has the function of radiating outwards part of the heat absorbed from the sun.

This process can be seen in the temperature change with height. At the Tropopause most of the heat has gone but then there is a temperature increase from the reaction of ultraviolet with ozone in the stratosphere.

The earth is also cooled by evaporation of water, extracting latent heat. The moister atmosphere deposits the water higher us as clouds, releasing the heat. Precipitation sets up a cycle of this process.

In a greenhouse, the heated and moister air cannot mix with the entire atmosphere outside, and is therefore warmer than outside.

In the earth’s atmosphere both the heat and the moisture in the air are distributed around the world by wind, enhanced by turbulence, which is highest over the land. Heat absorbed by the ocean is distributed by ocean currents.

tvshThe graph of atmospheric temperature with height is confusing as it is for an average climate, so it tries to combine what are quite different conditions, the climate with the sun and the climate without the sun.

With the sun, the heated earth’s surface cools by convection and evaporation of water as well as by radiation.

Without the sun, it cools by radiation but is warmed by the previously heated air and by deposition of moisture as dew or frost. The turbulence from winds is greater on land than on the ocean and it enhances air and moisture movement. On a calm day the earth is warmer. On a calm night it is cooler but deposition of dew and frost reduce the surface cooling.

Et tu, CO2?

THE CARBON DIOXIDE GREENHOUSE EFFECT

The claims of Arrhenius to have found a warming influence from an increase in atmospheric carbon dioxide were largely ignored for some 30 years, because the claims were doubtful, and the world was preoccupied with a world war and an economic crisis.

Guy Stewart Callendar  was an English steam engineer and inventor  who published many studies and articles which revived the claim by Arrhenius that increased atmospheric carbon dioxide heated the earth. He measured the absorption spectrum of water vapour and carbon dioxide and that of the sky. He ignored water vapour and even believed that radiation was the only form of energy transfer.

I pause here for astonishment at the sight of a steam engineer apparently unable to recognize the thermodynamic properties of water.

Sir George Simpson, the eminent meteorologist, who was, at that time, Director of the UK Meteorological Office, in commenting on this paper said

It is not sufficiently realised by non-meteorologists who come for the first time to help the Society in its study that it was impossible to solve the temperature distribution in the atmosphere by working out the radiation. The atmosphere was not in a state of radiative equilibrium, and it also received heat by transfer from one part to another. In the second place, one had to remember that the temperature distribution in the atmosphere was determined almost entirely by the movement of air up and down. This forced the atmosphere into a temperature distribution which was quite out of balance with the radiation. One could not, therefore, calculate the effect of changing any one factor in the atmosphere, and he felt that the actual numerical results which Mr Callendar had obtained could not be used to give a definite indication of the order of magnitude of the effect.

These remarks have been comprehensively ignored ever since.

MODERN DEVELOPMENTS

Since the 1980s, considerable effort has been spent on developing the theory that Callendar presented, that the energy of the climate is primarily controlled by absorption of the earth’s radiation by carbon dioxide and other minor trace gases. …

The Intergovernmental Panel on Climate Change was set up in order to prove this theory, and despite their four major reports and several minor ones they have failed to do so. They have persisted in claiming that all energy changes in our atmosphere are dominated by radiation.

The basic climate models upon which these claims are based have evolved from the time of Arrhenius and Callendar. The 1997 version of Kiehl and Trenberth (KT97) was the most important first basic concept at that time.KT97.png

This has recently been revised by Trenberth, Fasulla and Kiehl (TFK09)

TFK09.png

You have to admit that those are pretty pictures. Alas, as Dr Gray pointed out:

All the figures (except for the imbalance of 0.9W/msq in the second graph) are given as if they were known to an exact amount, when they actually represent averages of quantities that are very inaccurately known, or even just guessed. No estimates of accuracy are give for any of them. For the supposed surface radiation from the earth it would be necessary not just to have a figure for the average temperature but for the average of the fourth power of the absolute temperature. Neither of these quantities are known.

A major error is the claim that it is possible to average day and night. The climate by day is a quite different problem from the climate at night. By day the earth has a constant supply of energy, so it resembles a perpetual motion machine. By night, without the sun, it would tend to thermodynamic equilibrium. Many of the figures would have very different values in the daytime than at night, yet they are quoted as averages, as if the sun shines all the time.

So the planet on which we live, has to have the sun shining, rather dimly and constantly, for the models to work.

Gerlich and Tscheuscher try to argue that the climate cannot be regarded as equivalent to a heat pump because the external energy to a heat pump is work instead of solar radiation. They give as references for the view that external energy has to be work two publications by Clausius. The English translation at least, does not support the view that since the climate is not fuelled by “external work” therefore it cannot violate the Second Law of Thermodynamics. This view is, however, supported by some textbooks (e.g. Smith and Cooper). It cannot be right because it would involve violation of the Stefan Boltzmann and Planck’s laws of radiation.

The ultimate source of all the energy on the earth (except geothermal and cosmic rays) is from solar energy, and this includes work and electric power. Any system fuelled by any form of external energy does not need to comply with the second law of thermodynamics.

A very important point. For all sides.

It should be noted that the claimed global warming from the absorption of infra red radiation by trace gases calculated from the TFK model is a mere 1.6 W/m² since 1700. From their own figures changes in convection and evaporation could easily
amount to more than this. They could arrive merely by a different choice of the figures reported by the authorities quoted or by any variability over time. The models do not therefore provide a convincing case for the existence of the carbon dioxide greenhouse effect.

Changes in convection and evaporation could be caused naturally, by changes in the earth’s orbit, in the radiation from the sun, cosmic rays, ocean circulation and volcanic eruptions.

The amount of heat lost by convection and evaporation would also be influenced by anthropogenic efforts to reduce convection or evaporation, so these could be considered as contributions to “global warming” if any such warming is detected.

The good Doctor’s heresies continue, resorting to application of basic principles of heat transfer:

Devices that capture part of the natural heat loss such as windmills or solar panels actually cause global warming, for they remove part of the heat that would otherwise be removed by convection, and so inhibit cooling. Inhibition of daytime cooling is caused by urbanisation and land use change giving an upwards bias to temperature readings by weather stations.

I have pointed out in my “Greenhouse Delusion” 45 that the average 0.02 W/m² of heat which is generated by humans is very unevenly distributed and there are some industrial areas where the amount generated exceeds that attributed to the supposed greenhouse effect of 1.6W/m² since 1700 by almost 100 times. The attached graph (from Tom Quirk) shows how this heat is predominantly emitted between 30-60 degrees N. It is obvious that temperature measurements which are predominantly collected from these regions will give an upwardly biased view of global temperature as they concentrate on those areas most likely to warm from urban change. Measurements of carbon dioxide concentration which do not include these areas are likely to be downwardly biased.

CONCLUSIONS

Fourier, Pouillet and Tyndall believed the earth was warmed by absorption of the sun’s rays by the atmosphere. Tyndall considered that it was due to water vapour. Arrhenius first claimed absorption of radiation from the earth by trace gases but he inadvertently measured the effects of water vapour instead of carbon dioxide. Callendar launched the carbon dioxide greenhouse effect despite the objections of Sir George Simpson who considered he had ignored air movement.

R W Wood was the first to show that the air in a greenhouse is heated by convection, but he did not notice that this meant the air cooled the surfaces by day, or that the warming function of a greenhouse is when the sun does not shine.

A theory similar to that of a greenhouse applied to the earth’s climate. Convection and evaporation cool the earth by day and reverse convection and deposition of water or frost help to reduce night time cooling.

Even the official IPCC climate models admit that changes in these climate influences could be greater than claimed effects of trace gas emissions. Human attempts to interfere with convection and evaporation are a far more likely cause of possible global warming than changes in trace gases in the climate.

The “UN-IPCC scientists” behave as do the dogs in Proverbs 26:11.

But that is to be expected because to some; having a problem is more important than finding it not to be a problem.

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