"The Gravito-Thermal Greenhouse Effect"

UPDATE May 2021. I've boiled this all down to a simple explanation based on common sense, basic maths and a rudimentary knowledge of the Gas Laws.

Please read my post Acceleration ≈ Gravity
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It appears that I have wasted all week trying to explain this effect, which seems blindingly obvious to me as it fits in with everything else we know about anything and I'm pretty sure that our physics teacher mentioned it once in passing:

Earth surface temperature (as well as the surface temperatures of 5 other rocky planets in our solar system) can be very accurately determined solely on the basis of two variables:
1. atmospheric pressure at the surface, and
2. solar irradiance at the top of the atmosphere.

For sure, it is only a starting point and you will probably have to make lots of other little up and- downward adjustments, but having Googled around, as per usual anything which offers an alternative/complementary/non-GHG induced explanation for why surface temperatures are what they are gets mired in purely political controversy and nit picking.

As PaulC points out, the paper linked to was withdrawn (yes I knew that), but an idea is not responsible for the people who hold it (pace Bayard). It is even hotly debated whether luminaries such as Maxwell and Feynman supported or rejected the idea, that's how mad it is.

I don't see how hard it can be to do all the measurements of a few different planets with differing atmospheres (I'm not sure why we should restrict it to rocky planets) and settle the matter one way or another to everybody's satisfaction, but hey...

Politics of a Citizen's Income paid from a Land Value Tax

The following assumes no other changes to our tax and benefits system whatsoever.

According to Savills residential property values in the UK are £6,165bn. There are 28.2 million dwellings in the UK.

Let us assume that LVT is the equivalent to 3% tax on the current selling price of each home.

Total potential LVT revenues are £185bn.

UK population is 64.6 million.


A Citizen's Income from which we all get an equal share of LVT = £2,864 per person (including children).

Property value London/SE = £2,772 bn, LVT = £83 bn pa
Property value other regions = £3,393 bn, LVT = £102 bn pa

Population London/SE = 17.4m, Citizens Income = £50 bn pa
Population other regions = 47.2m, Citizens Income = £135 bn pa

Net flow of income to regions outside London/SE = £33 bn pa

Break even point for owner occupiers = £95,500 property value per person

So a household consisting of a couple with two children would be no better or worse off if they lived in a home worth £382,000.

Average UK house price £218,474.

                                                              Conclusion.

Almost all constituencies outside London/SE would be better off under a LVT + CI.

Couples with two children living in a house worth £382,000 or less (176% of current average house prices) would be better off.

Over half of Londoners who now live in rented accommodation would be better off.

In short, only a small minority of UK constituencies, mainly in the SE of England would be worse off and vote against such a proposal.

As well as reducing both regional and individual inequality, LVT + CI would allow the market to allocate property at optimal efficiency, reducing vacancies and under-occupation.

It would also reduce the selling price of property to its capital only value. Saving future title holders £36bn per year in mortgage interest repayments. (assuming current outstanding mortgages total £971bn would be reduced to £324bn)

A win-win-win.

For the purposes of a clear illustration of distributional effects, no changes to our tax and benefits system take place. However, it would be better if as many bad taxes were replaced with an LVT as possible, and our benefits system largely replaced with a Citizen's Income. Reducing the deadweight losses associated with each.

A win-win-win-win.

All we need is some politicians who can make a good pitch...

Gravity is more or less the same as acceleration.

From Quora:

Q: Obviously, the source of acceleration (without gravity) is transfer of energy from one object to another or change of its own energy structure so that one of its components changes into increasing energy of motion. But gravity occurs with no measurable energy transfer nor is the gravitating mass changing its energy structure in order to produce gravity.

If the cause of acceleration and gravity is not related at all is the Equivalence principle just a coincidence that the resulting effects are physically identical and indistinguishable?

A: By Frank Heile, PhD in Physics from Stanford University

I will try to describe in detail how gravitation works and how acceleration works and why the two different phenomena are really equivalent...

There follows a long and complicated explanation and comparison, but in folksy terms, anybody who has ever swung a bucket of water over his head at the right angle and speed knows this. As far as the water in the bucket is concerned, there is no difference between the gravity and the centripetal force/acceleration* while it is upside down. See also Einstein's famous thought experiment with the man in the accelerating spaceship.

* Acceleration is change in speed OR in direction, see here.

I refer you now to the comment by Nobel Prize nominee Ralph Musgrave:

Assume there’s just one atom in a car cylinder which is at room temperature. The atom bounces up and down between the piston and the top of the cylinder. Atoms at room temperature move around at about 1,000mph. If the piston then moves upwards at 1mph to its “maximum compression” point, the atom will gain a good 100mph in speed.

How is that possible, given the paltry speed of the piston? Answer… During the half second or so during which the piston is moving, the atom collides with it a hundred times or so, and it gains 1mph each time. I’d appreciate nominations for a Nobel Prize for this amazing insight.

So for air at ground level, the effect of gravity is like being driven by a giant piston accelerating at that speed and every time it bounces off the piston (the surface of the earth), it travels back faster than it set off (I'm not clever enough to work out how much faster at this stage and if so, relative to what). Relative to the surface of the earth there is no change in observed speed, just in direction (which as explained above, is acceleration).

Now imagine sweeping up sawdust with long straight strokes of a broom, you will get a bow wave in front of the broom where the sawdust is deeper, the broom is pushing saw dust which is pushing more sawdust etc. The pile is deepest directly in front of the broom and slopes away from it, the sawdust far ahead of the broom is entirely unaffected.

Which is why the atmosphere is thicker at the bottom. Which is another way of explaining why, from the point of view of an individual O or N molecule, in gravity/pressure/temperature* terms, the atmosphere is not static, it is constantly being accelerated from underneath by a giant piston (the surface of the earth), the same as the sawdust in front of the broom is being accelerated by the broom itself or by other bits of sawdust etc.

Like a bow wave, the force is carried ever upwards, so molecules in the upper atmosphere are bounced further out than they would reach under their own devices. So the upper atmosphere is less dense than it 'should' be and hence is cooler than it 'should' be, i.e. cooler than the surface of the Earth in the same way as the lower atmosphere is warmer than it 'should' be etc. To use another analogy, the atmosphere acts like a heat pump or fridge, it transfers heat from some places (cools them) to other places (warms them) but without changing the overall amount of 'heat'.

* I accept that there is minority few that increasing the pressure of a gas does not directly increase its temperature, which would mean that a lot of textbooks are very, very wrong on this one!

"What happens to the temperature when an ideal gas is compressed?"

From Wiki:

A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. Compression of a gas naturally increases its temperature.

A lot of people seem to be stuck on that and blankly refuse to accept what is almost a truism. For a gas, pressure and temperature are almost the same thing. Increase/decrease either and you increase/decrease the other (until it levels out at the temperature of its surroundings, obis).

Dinero refuses to grasp this point:

"The main point is - There is no physical law that equates constant high pressure to constant high temperature. If you think there is then state it. As I said in an earlier comment Scuba diving tanks that are full with compressed air are actually not warm to the touch."

The metal skin of scuba tanks is a good heat conductor/poor heat insulator, so the overall temperature of the tank and the compressed gas (liquid?) inside it is the same as the surrounding air. Duh. But what happens when you reduce the pressure on that gas by releasing the valve? It cools down. You notice this when you are refilling a cigarette lighter with compressed gas, there will be ice round the opening where the moisture in the air has frozen. This is the basic "how a fridge works" model, see below.

So allow me to present related matters illustrating this single phenomenon, which is quite independent of sunshine or insulating effects of clouds and other minor greenhouse gases, can we please focus on the topic in hand...

1. From here:

In Lectures of physics, vol 1 by Feynman, it is written:

"Suppose that the piston moves inward, so that the atoms are slowly compressed into a smaller space. What happens when an atom hits the moving piston? Evidently it picks up speed from the collision. [...] So the atoms are "hotter" when they come away from the piston than they were before they struck it. Therefore all the atoms which are in the vessel will have picked up speed. This means that when we compress a gas slowly, the temperature of the gas increases."

Obviously, if the gas under pressure is not in a perfectly heat-insulated container, it will cool down again/warm its surroundings. Which is why Boyle had to wait for his compressed gases to cool down again before observing that pressure is proportional to volume; the immediate reading showed a higher pressure/temperature. Taking the atmosphere as a whole, it is in fact a self-contained heat-insulated container which contains itself. Gravity does the 'work' holding it in and the vacuum outside is to all intents and purposes a perfect heat insulator*.

The reverse is also true, if the volume of a sealed container with gas in it is increased, the gas will cool (until it is warmed up again by the non-insulating container).

2. See for example how fridges work:

A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers.

In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly below the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor.

The superheated vapor travels under pressure through coils or tubes that make up the condenser; the coils or tubes are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature.

This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. The sudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as auto-refrigeration.

Clearly, there is an added kicker here, the latent heat absorbed when the compressed gas (liquid) boils/evaporates again, but the principle stands. Heat coming out of the back of the fridge is equal and opposite to the fall in temperature inside the fridge (ignoring the extra bit of heat generated by friction).

3. Or let us take a jaunt into space and see what scientists say about the atmosphere of Saturn, which is so far out that the warming effect of the Sun is negligible:

Saturn's temperature and pressure increase from the exterior of the planet toward its center, changing the makeup of the clouds. The upper layers of clouds are made up of ammonia ice. Traveling toward the core, clouds of water ice form, with bands of ammonium hydrosulfide ice intermixed. The lower layers of Saturn see higher temperatures and pressures. Water droplets are found here, mixed with ammonia.

Or how about Jupiter:

The center of Jupiter is more than 11 times deeper than Earth's center and the pressure may be 50 million to 100 million times that on Earth's surface! The tremendous pressure at the center of planets causes the temperatures there to be surprisingly high. At their cores, Jupiter and Saturn are much hotter than the surface of the Sun!

Strange things happen to matter under these extraordinary temperatures and pressures. Hydrogen, along with helium, is the main ingredient of Jupiter's and Saturn's atmospheres. Deep in their atmospheres, the hydrogen turns into a liquid. Deeper still, the liquid hydrogen turns into a metal!

We can pretty much rule out the Sun as a source of this heat, and their atmospheres are mainly H and He with practically no traditional greenhouse gases. Leaving us with one surviving explanation of the three as to why they are so hot in the middle.

What you have to remember is that we think of as the 'surface' of the earth is in fact the bottom of our (relatively thin) atmosphere (where the pressure induced warming is strongest), and the 'surface' of gas giants is the top of their (very thick) atmospheres.

PaulC156 keeps digging in the comments:

"So gravity exerts a force on matter which thus transfers energy of motion / kinetic energy which in turn can be measured by increases in pressure, density and temperature. Nothing controversial until you go from the general and ideal situation of a collection of molecules in space to the specific Earth bound circumstance of an atmosphere over a heated surface."

Jolly good, some agreement, so what is heating the centres of gas giants? Are they not just collections of molecules in space?

"That latter phenomenon [from inbound ultra violet from the sun transforming to out bound infra red] is given a token nod in the form of ‘it may have a small impact of a couple of degrees’. This is just hand waving."

No it is not given a token nod, the whole phenomenon of clouds reflecting the Sun's rays back up or back down when it's cloudy, and CO2 and CH4 turning long wave into short wave radiation and reflecting some of it back down is incontrovertibly true - but it is a completely separate phenomenon. The same as the Sun heating things up in the first place. They are not three alternative explanations for the same thing and we ought not waste time arguing over which is 'correct', they are three quite independent factors which are all have an effect.

It is like accelerating in a car when you are going downhill, there is no point having an argument over whether it is accelerating purely because of gravity or purely because you've pressed the accelerator, as both are having the same effect to some degree, the interesting bit is splitting up the total acceleration into the part due to gravity and the part due to pressing the accelerator.

So I might as well point out that PaulC156 (not his real name!) is only giving the basic Gas Laws a token nod.

Bayard also refuses to accept that the extreme case of what happens in the middle of gas giants is repeated on a small scale in the Earth's atmosphere:

"Mark you still haven't made the necessary distinction between movement (of mass) and static states. To all intents and purposed the Earth's atmosphere is static…"

To all intents and purposes, the H and He which make up 99% of the volume of Jovian Planets (a fancy name for gas giants) are static. It floats up, it sinks down etc.

4. Or even further afield and ask how stars form:

Gravity pulls the dust and gas together.

As the gas falls together, it gets hot. A star forms when it is hot enough for nuclear reactions to start. This releases energy, and keeps the star hot.

Where does heat come from? From gravity compressing the hydrogen atoms/molecules. Luckily, the earth does not get anywhere hot enough to trigger nuclear reactions!
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* Mombers adds:

Big hole in your analysis I think:
'the vacuum outside is to all intents and purposes a perfect heat insulator'
The vacuum provides no insulation for the radiant heat, which is why nights are colder than days.
Greenhouse gases on the other hand do provide insulation for radiant heat...

1. Yes, fair point, heat radiates from the earth equal and opposite to what comes in from the Sun. The net effect is zero. But let us rule the Sun out of this equation. There was no Sun shining on the earliest clouds of hydrogen, but nonetheless, they heated up (see also Saturn, Jupiter, above), the heat did not radiate out into space or else they would never have ignited. Deny that if you will. I am talking about a specific phenomenon that is independent of heat from the Sun.

2. The vacuum provides the same (lack of) insulation in daytime and night time. As far as I am aware, the reason it is colder at night is because the Sun is not shining on that part of the earth. The relative difference between temperature "where the Sun is shining" and "where it isn't shining" is a separate topic (and easily explained) to "why is it warmer at ground level than at higher altitudes (for a given surface temperature)".

3. Of course greenhouse gases i.e. clouds of H2O vapour reflect radiant heat. Everybody can notice that when it is cloudy at night it is surprisingly warm. That is quite a separate topic to "why is it warmer at ground level than at higher altitudes (for a given surface temperature)". Clouds at low elevation (fog) are warmer than clouds higher up.

"It's healthier to cycle than drive"

A recent reader's letter in The Evening Standard:

On Wednesday air pollution in outer London was worse than in central London, according to AirText. No doubt potential cyclists were put off by the nitrogen dioxide and particulates they would breathe in but as tests by Enviro Technology Services earlier this year showed, air pollution is actually worse inside cars than outside.

Nitrogen dioxide inflames the lungs, stunts growth and increases the risk of respiratory diseases such as asthma and lung cancer, particularly in children. So, despite the poor air quality, it is healthier to cycle than to drive.

Today marks the beginning of European Mobility Week, which aims to encourage local authorities to introduce and promote sustainable transport alternatives to cars. Only two authorities in the capital have signed up — Lambeth and the City of London.

In the week that the Government rejected a diesel scrappage scheme we all need to consider giving cycling, walking and public transport a go. The car is no longer king — and its pollution is killing us.

Andree Frieze, Make Air Safe & Clean (MASC)

Well, clearly it's not healthier to cycle than drive, unless you ignore the hundreds of people injured or killed while cycling, plus the nuisance value of the lycra crew blocking the roads when you want to go for a spin.

Assuming the facts as stated to be true, the solution to maximising your personal health/safety level is blindingly obvious:

a) Take the bus or train when travelling to inner London.

b) Drive a convertible car with the roof down when travelling around outer or outside London (or at least open the sun-roof and all the windows in a normal car).

Fun Online Polls: Atmospheric temperatures, politicians and sugar

The results to last week's Fun Online Poll were as follows:

Why is the earth's surface 30C warmer than it should be, and 60C warmer than the top of Mount Everest?

Greenhouse gases like H2O and CO2 - 20%
Gravity and Boyle's Law warm the lower and cool the upper atmosphere - 67%
Other, please specify - 14%

Which was of course the correct answer. I was told that more specifically I should have said Gay-Lussac's Pressure-Temperature Law:

"The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas's absolute temperature."

(Though having re-read this, they seem to be saying the same thing.)

Atmospheric pressure at ground level is higher than at the highest altitudes, ergo it is warmer than it would be from sunshine alone, and at the top of the atmosphere, it is colder than the average temperature of the whole atmosphere.

Clearly heat can't come from nowhere so what the lower atmosphere gains (in terms of average number of molecules per unit volume with a correspondingly higher total kinetic energy of those molecules per unit volume, which can be measured as 'pressure' or 'temperature', same thing in this context) must be balanced out by lower numbers for density, temperature, pressure etc in the higher atmosphere .

There is an equilibrium, which depends on how thick the atmosphere is, the air at the bottom can only warm up so far before it rises and cools again; the air can only rise so far before the force of gravity pulling it down overrides its tendency to float up etc.

It's all well and good coming up with an explanation why the surface temperature is higher than it would be from sunshine alone (and yes, 'greenhouse' gases like H2O, CO2, CH4 contribute a couple of degrees but not a massive amount) but if that does not also explain why the upper reaches of the atmosphere* are colder than they would be etc, then that explanation is not coherent or plausible.

* Don't start with the thermosphere, that is high up but hot for very different reasons.
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Going back to a Fun Online Poll of a few weeks ago, 71% thought that Merkel would never realise it was wrong to let a million Muslim refugees into the country.

Interestingly, she sort of did today, although it wasn't really an apology as such, more that she regrets having lost votes over it and wishes she had prepared the ground better before she pressed ahead and did it anyway.
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On the topic of politicians, another politician-avoiding-sugar story popped up again today, I don't know why some people are so obsessed with other people's diets but hey, I try to avoid sugar where poss so he has my sympathy (although I don't make jam, don't really like the stuff).

From The Daily Mail:

* The Labour leader made the comment during a chat on Mumsnet
* Said he shunned biscuits because he was 'anti-sugar on health grounds'
* But mocked as he has a jam-making hobby, which usually involves sugar

Luckily, the internet never forgets. For contrast, there was another politician-avoids-sugar story a while back, which raised no eyebrows whatsoever.

So that's this week's Fun Online Poll (without following that last link first!)

"Which of these politicians avoids sugar?"

Vote here or use the widget in the side bar.

Short Lists

Major political parties in Great Britain* with a male leader

Labour Party
Liberal Democrat Party

Much longer list:
Major political parties in Great Britain with a female leader

Green Party**
Plaid Cymru
SNP
Conservatives***
UKIP

* GB excludes Northern Ireland. That bastion of male chauvinism only has one major party with a female leader.

** Yes I know that technically they have two joint leaders and one is a bloke, but Caroline Lucas is the only one anybody's heard of.

*** Which gives me another idea for a short list: "European countries with a female prime minister/chancellor etc who never had children"

I expected a "despite Brexit fears" bonanza but was disappointed

From the BBC:

Bank admits economy is looking better

In one sentence the Bank has revealed it is ready to upgrade its growth forecasts for the UK economy.

"The Committee now expects less of a slowing in UK GDP growth in the second half of 2016," it said, referring to the Monetary Policy Committee of Bank economists and external experts that sets UK interest rates.

The key point - the Bank's internal judgement is that growth in Q3 (that's July to September) will now be between 0.2% and 0.3%, a pretty chunky upgrade on its August forecast of 0.1%.

A most interesting headline from the BBC. Even they appear to realise that Project Fear was overcooked and are trying to distance themselves from it.

I'll be pleasantly surprised if this gets past the City AM moderators.

Kristian Nimitz wheeled out his Faux Lib nonsense for the umpteenth time.

Shooting the messenger: Rent controls have always and everywhere ended in failure

Quite clearly, in the real world they haven't, sometimes yes, usually no, depends on other factors.

My actual comment:

Badly wrong on at least two counts.

The UK had rent controls for most of the 20th century, but that did not mean that housing supply disappeared. All that happened was that landlords left the market - meaning there were more homes for owner-occupiers to buy, who also acquired all new supply.

(In European countries, rent controls coupled with yet another "government interference" i.e. minimum building standards have also led to favourable outcomes.)

This is a large part of the reason why owner-occupation rates doubled in the decades after 1945 and the number of private tenants halved.

Another major reason was that mortgage loans were capped at low income multiples, which set a natural cap on house prices.

His other glaring error is that granting even more planning permission will make no difference, it is pushing a piece of string. Land bankers/home builder have a profit maximising level of output of about 150,000 a year. If more permissions are granted, these are simply banked, which is why the largest home builders are sitting on land banks with planning sufficient for ten years' supply.

If Mr Nimitz left his ivory tower for a few minutes and took the trouble to read the accounts of Barrats, Persimmon et al, this would be obvious to him.

I imagine that the third mechanism adopted by UK governments to put a natural cap on rents and hence house prices will be completely unpalatable to Mr Nimitz. That was the easy availability of low rent social housing, which enabled millions to opt out of the land price Ponzi scheme altogether.
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UPDATE, re Anti's comment.

The more complete list of policies which the UK had in one form or another for most of the 20th century until the Home-Owner-Ist era is as follows:

- rent controls (came in hard after each war, were then gradually whittled away)
- tenants were protected from eviction, as long as up to date with rent (until 1996 or so)
- as a result, neither banks nor building societies would lend to buy-to-let landlords (until 1997 or so)
- higher taxes on landlords' rental income
- private landlords not subsidised by Housing Benefit (until 1990).
- Domestic Rates (until 1990)/Schedule A tax (until 1964), which together were more like LVT than like Council Tax.
- little or no bank lending on land/mortgages.
- building societies had stricter criteria on minimum deposits and maximum loans-to-income multiples. If you can't borrow more than twice your joint income, that caps house prices at just above twice your joint income.
- there was the opt out from the whole Ponzi scheme i.e. social housing (peaked at 30% of all households in the 1970s).
- lower house prices meant that builders increased profits by increasing volume/quality; not by restricting supply to prop up prices, so little or no land banking.
- general political assumption that owner-occupation is the best form of tenure
- general cultural assumption that landlords were a bit sleazy, barely a step up from brothel owners or benefit claimants.

The inevitable result was low rents, low house prices, small and resilient banks and building societies…

… and rapidly increasing owner-occupation levels, which is where this Georgism-lite contained the seeds of its own demise and tipped over into Home-Owner-Ism again. The country is run by politicians who want to buy votes as cheaply as possible, so from the 1960s onwards, there was a political advantage in allowing house prices to increase year on year - a notional profit for a majority of voters and an invisible cost for future generations, all requiring zero tax increases.

Fast forward to last year, the scales were tipping the other way, more people were losing out from Home-Owner-Ism than were gaining, so the then Conservative chancellor started withdrawing tax breaks from buy-to-let landlords, ostensibly to shift the balance from landlords back to would-be owner-occupiers. If the shift from Home-Owner-Ism back to Georgism-lite takes as long as the other way, we will have Georgism-lite again by the middle of this century.

That "Bake off moves to Channel 4" story - the Daily Mail digs up the relevant facts and figures

The couple's home in Clapham is worth £3.5million and they live in it with their three children


That's all we need to know, isn't it?