Sunday, 21 June 2020

I'm shelving that plan for a book on the Real Greenhouse Effect...

It turns out that far greater and better qualified minds than mine have been pointing out the real (and blindingly obvious) reason for The Greenhouse Effect since the late 19th century, all to no avail. So it's not like I can make any difference and I'll just do one final blog post (I gave this a lot of thought while painting our kitchen cabinet doors last week but was too knackered to post anything) and call it a day.

A good place to start is at Tallbloke's Blog. Some of the modern day proponents are moderate and sensible, others seem to be a bit unpleasant and/or borderline mad. Take your pick, but that doesn't invalidate the explanation. Isaac Newton was a towering maths and science genius, but an unpleasant person to deal with and he also believed in transmutation of elements. So what?

All proponents have a slightly different way of explaining it, but it is of general application and explains so much that the Alleged Greenhouse Effect doesn't and can't. Suffice to say, the Consensus derides them all as crackpots and/or Science Deniers.

What it boils down can be illustrated for Earth's atmosphere as follows. The total energy (thermal plus potential) of any molecule at every altitude tends to equalise. Clearly, you don't measure potential energy in degrees K, you measure it in Joules, but they are of equivalent value. (Like somebody running a hydro-electric power station makes a trade off between "water up in the reservoir" and "kilowatt hours of electricity". There is a trade off between kg's and kWh's and they add up to the same total energy value, ignoring conversion losses/inefficiency):

That's my new flag! Fuller explanation (and the planned introductory chapters) as follows:

1. 'Energy' is just 'energy' and it takes on, or can be stored in, different forms, such as
- photons/radiation,
- kinetic energy (on large scale) or thermal energy (kinetic energy on a molecular scale),
- potential energy (height x gravity),
- latent heat of evaporation.
Those are the main ones we need to think about in terms of the atmosphere. There are others such as
- chemical energy,
- electrical energy,
- matter (which can be converted back to energy in nuclear fusion or fission)
but these are not so relevant here.

2. Energy can be converted from one form to another without overall losses. For sure, with plants and animals, or engineering, in any process some of your starting energy is converted to forms you didn't want or can't use, but that doesn't apply when energy in the atmosphere swaps between thermal energy and potential energy (convection) or back again, and this process is to all intents and purposes 100% efficient.

A good example of this two-way conversion is using spare/cheap electricity at night to pump water up into reservoirs (electrical energy is converted to potential energy). Then at times of peak demand, the sluice gates are opened, the water goes through turbines and generates electricity (potential energy is converted back to electrical energy). (Clearly this is not 100% efficient, in that some energy is lost to evaporation, vibration, heat/friction, sparks etc.)

Similarly, if you throw a ball vertically, it starts off with a lot of kinetic energy (it's moving fast); it then slows down and gains height (kinetic energy is converted to potential energy); it reaches a point where it is momentarily stationary (zero kinetic energy, maximum potential energy); on the way down, the reverse happens. Ignoring air resistance, the total energy of the ball remains constant. Analogies are never perfect, but this is similar to what happens in the atmosphere.

3. There are names for the processes when energy changes (or is converted) from one form to another.

Objects warm up when bright lights shine on them. When a warm object cools down, it 'radiates'.

We 'generate' electricity by converting thermal energy, solar radiation or kinetic energy into electricity. We 'use' electricity to create heat, light or movement.

When plants convert solar radiation to chemical energy, it is called 'photosynthesis'. We 'burn' things with stored chemical energy (wood) to create thermal energy and light.

When water evaporates, some of the thermal energy needed does not increase the temperature of the water directly. It is 'used' to convert water from liquid to gas and is stored by the water vapour as 'latent heat of evaporation'. So the land from which the water evaporates cools down by more than the water warms up, if you just measure it with a thermometer. This energy does not disappear (of course), it is just a different form of energy. When the water vapour condenses, it releases that latent heat as actual heat again (which is mainly why the observed lapse rate is only two-thirds of the predicted dry lapse rate).

I don't know if there is a word for kinetic energy being converted to potential energy (and back) when you throw up a ball (and it falls again).

When air is warmer than it surroundings, it expands, rises and cools ('convection') and thermal energy (kinetic energy on a molecular scale) is converted to potential energy (similar to a ball thrown upwards). For every bit of warm air that rises, another bit somewhere else falls down, is compressed and warms up, so the potential energy it had is converted to thermal energy again. Unfortunately there is no word for the opposite of 'convection'.

The meteorologists refer to the potential temperature of air. Although they are interested in unstable situations (because that's what makes the weather happen), it is the same sort of concept. The potential temperature is the temperature that the parcel of air would be if it were brought down to sea level atmospheric pressure. So it dry air at sea level is 288K, dry air which is 1 km above sea level and has an actual temperature of 278K also has a potential temperature of 288K and the two are in a neutral equilibrium.

It would be very helpful to split the potential temperature into a) actual temperature and b) the 'latent heat of convection' analogous to 'latent heat of evaporation' (or the 'latent speed' of a stationary ball at the top of its flight), because just like the 'latent heat of evaporation', which reappears as actual thermal energy when water vapour condenses, the 'latent heat of convection' (which cannot be measured with a thermometer) turns into actual thermal energy when air falls again.

For our purposes, we don't actually need to worry about whether energy in the atmosphere is transferred by conduction, convection, radiation, latent heat or anything else - the final distribution or equilibrium will be the same in the long run.

We also don't need to worry about how the energy gets into the atmosphere in the first place, which is mainly by solar radiation hitting the hard surface, the ocean surface or the clouds (occasionally it's a volcanic eruption or a meteor hitting it), because that doesn't affect the final distribution. That would be like assuming that the surface height of a lake depends on which ends is being rained on; or that a bath warms up more at the end where you pour in a bucket of hot water.

4. Energy tries to spread out as evenly as possible.

This is easy if we are just looking at one type. If rain falls at on end of a long lake, the water level in the whole lake rises by the same amount, or else the surface at the rainy end would be higher and have more potential energy than the sunny end. If you pour a bucket of hot water into one end of a lukewarm bath and wait for a few minutes, the temperature of the whole bath will go up by the same amount.

But in the atmosphere, potential energy can't be the same all the way up. This is the key to the whole thing. The top layer will always have the most potential energy and the bottom layer will have none. So energy does the next best thing and adjusts temperature so that the total energy (thermal plus potential) of any molecule at any altitude tends to equalise, which it is why it is so easy to understand the formula for the lapse rate (gravity ÷ specific heat capacity), it's just the trade off between the two forms of energy (on Earth, we have to adjust this down by one-third because of the latent heat of evaporation/condensation of water/vapour).

Rather unsurprisingly, because the average temperature of the atmosphere is 99.9% dictated by incoming solar radiation, the average temperature of the whole atmosphere is what you would expect it to be from that incoming solar radiation (i.e. 255 degrees K, the 'effective temperature'), but this thermal energy is not distributed evenly all the way up; there is more at sea level (288 K) and less at the top of the troposphere (213 K) - see chart above.

5. The normal gas laws have to be modified over large scales where gravity is relevant

The normal gas laws apply on a small scale in a sealed container (where you can safely ignore gravity) and tell us that temperature, pressure and density will all even out. But this does not apply on the large vertical scale in the atmosphere where gravity is important and where there are no sidewalls (a molecule that moves sideways hits another molecule, it never hits a wall) or lid (unless you count gravity as a lid?). Pressure and density fall as you go up through the atmosphere because of the effect of gravity, so why shouldn't temperature? Without gravity, there wouldn't be an atmosphere!

Molecules in the air are constantly moving and trying to reach an equilibrium. If a 'parcel of air' is slightly warmer than its surroundings, it will expand, rise and cool (these three go on tandem, you don't need to worry about what happens first). So it loses thermal energy (cools down) - and by rising, it gains potential energy. The potential energy doesn't come out of nowhere - thermal energy has been converted to potential energy.

For every 'parcel of air' that rises, other parcels move horizontally to fill the gap (aka 'wind'), and somewhere (over the Poles or on the night side) a parcel of air will be slightly cooler than its surroundings and it will fall to fill the gap left over by the last parcel that blew off horizontally. This parcel will be compressed into a smaller volume and its temperature will go up. That thermal energy doesn't come out of nowhere either - potential energy has been converted back into thermal energy. To use my terminology, the 'latent heat of convection' has been converted back into actual 'heat'.

Half way up the troposphere, a parcel of air has a certain amount of potential energy and a certain amount of thermal energy (that comes from solar radiation, which is our effective temperature of 255 K). The air above it will be cooler and the air below it will be warmer.

Summary... the Real Greenhouse Effect doesn't increase overall temperatures. It increases temperatures in the lower half of the troposphere and reduces them in the upper half. Same as a fridge, heat pump or vortex tube, which warm and cool simultaneously, they take thermal energy from somewhere and push it somewhere else. They do not increase overall average temperature or energy in the whole system. You don't get something for nothing!

6. The Consensus view (to the extent it has a view, each climatologist offers two or three self-contradictory explanations) makes unsupported assumptions and reaches unrealistic conclusions (see for example here):
- in the absence of Greenhouse Gases, there would be no lapse rate, temperature would be 255K all the way up;
- Greenhouse Gases trap thermal energy at the hard surface/sea level by reflecting/re-radiating it downwards, making and lower layers warmer and the upper layers colder;
- potential energy can be ignored completely.

Which can be illustrated as follows:

7. This appears to me to be science denial on a grand scale, and ignores and/or can't explain all the stuff we can observe and have reasonably good measurements for. If I had written the book, these would get a chapter each:

- it ignores the fact that the top of the troposphere and hence the peaks of very high mountains are a lot colder than we would calculate from solar radiation alone (see first chart). Their get-out is that Greenhouse Gases trap the heat lower down and keep the higher layers cooler, but that ignores potential energy completely and ignores the fact that mountain tops also receive solar radiation (so must be wrong);

- it ignores the fact that air is good at storing thermal energy, it warms slowly during the day and cools down even more slowly during the night. The total stored energy in the atmosphere and hard surface/ocean surface only goes up by 'a few per cent' on the day side and down by 'a few per cent' on the night side ('a few per cent' is probably about 5%). During the day, the air has a net cooling effect on the surface (like a car radiator) and vice versa during the night (like a radiator in a room);

- it ignores the fact that the oceans store more heat in their uppermost 3 meters than the entire atmosphere (let alone the thousands of metres of water below that);

- how clouds of hydrogen and helium gas contract to generate the pressure and temperature needed to kick start nuclear fusion;

- why there is a lapse rate on Jupiter or Saturn, even though their atmospheres are hydrogen and helium, which are officially not Greenhouse Gases (nitrogen and oxygen aren't officially Greenhouse Gases either). (Some astrophysicists consider Jupiter and Saturn to be failed stars - they are emitting more energy than than they receive from the sun, so must be gradually using up mass somehow);

- why the cores of Jupiter and Saturn are so hot, despite getting effectively zero solar radiation and why the hard surface of Venus is so hot, even though it only gets 17 W/m2 solar radiation (about one-tenth of what Earth's surface gets - clue - Venus' troposphere is heated from the clouds downwards using whatever the opposite of 'convection' is);

- why the Greenhouse Effect is stronger on the night side of Earth (which is getting zero solar radiation) and actually negative on the day side (which is getting all the solar radiation). The daytime temperatures on the surface of Earth are a lot cooler than the daytime temperatures on the Moon. On Venus, there is practically no difference between day and night surface temperatures;

- why the troposphere emits twice as much radiation or thermal energy towards the ground than it does out into space. The troposphere at sea level is warmer and hence emits more radiation that the layer higher up, which is colder and so emits less radiation, full stop.

- why water vapour and clouds (taken together) can't be a 'greenhouse gas', although this is based on observation as much as physics, which is really complicated.

- why the 'greenhouse effect' on Mars is barely measurable (no more than 5 degrees), even though there is twenty-five times as much CO2/m2 surface area as there is on Earth.

- why you can plot the Greenhouse Effect on Mars, Earth and Venus against the total mass of their atmospheres per m2 of surface and get a straight line, even though Earth's atmosphere is only 0.04% CO2 and Mars' and Venus' atmospheres are > 95% CO2.

- and so on and so forth.

It's all well and good having a theory or an explanation, but you have to be able to apply it to all the cases listed above and see whether they still hold. The kinetic-potential energy trade off explains 99% of all that without breaking a sweat. The Consensus have to invent all sorts of different explanations to paper over the cracks.
8. If I had a few million quid to spare, I'd settle the matter once and for all by buying an old industrial chimney or cooling tower - the taller the better - sealing it at the top, painting it white on the outside and insulating it with polystyrene on the inside walls, top and bottom - and then just measuring the temperature at top and bottom.

We would have real fun with this - we could test the theory to extremes by cutting holes near the top and bottom (on the side that gets the least solar radiation) and installing fans to pump in/suck out air; we would install radiators and cooling pipes at the top and bottom and turn them on and off; we would pump out the air and re-fill it with a mix of 80% nitrogen, 20% oxygen and zero Greenhouse Gases (H20, CO2 or methane).

I am quietly confident that, whatever you do; after you have turned off the pumps and closed the holes; or turned off whichever radiator or cooling pipes you had turned on; and left the column of air alone for long enough, the lapse rate will re-establish itself and the column of air will be cooler at the top than at the bottom by about 0.65 degrees per 100 metres of height (or nearly 1 degree if you manage to eliminate water vapour).

The only interesting thing left to resolve will be whether it takes seconds, minutes, hours or even days for the lapse rate to be re-established. If it hasn't happened after a week, if it's warmer at the top or if it's the same temperature all the way up, that's still a few million quid well spent and I shall spend a few quid more on a nice hat to eat.

I just wonder whether The Consensus would be prepare to enter into a bet and pay the costs if the explanation is correct. And I'll buy them a nice hat to eat as a consolation prize!