Friday, 22 May 2020

Missing figures - how to make the IPCC's figures add up

Their 'energy budget' was the topic of my two previous posts. If you summarise it, you get the following table:

That is the average for any 24-hour period in total. Problems arise if you try to dis-aggregate it into 'day' and 'night' (see previous post).

1. I think they didn't understand latent heat of evaporation (they show that the surface gives 80 W/m2 to the atmosphere) and the heat/potential energy transfers (they refer to this as 'thermals' and show that the surface gives 17 W/m2 to the troposphere).

Latent heat and potential energy can't be expressed in W/m2, they are expressed in Joules! They can't be measured with light sensitive equipment or with a thermometer! Some heat at the surface is converted to other forms of stored energy entirely.

Like trees - they capture a lot of light and some heat from the sun and convert it to stored energy i.e. chemical energy. This type of energy cannot be measured with light sensitive equipment or a thermometer! You can however convert this stored chemical energy back to a lot of heat and some light by burning it.

So while the surface is losing some its W/m2, those W/m2 are not being added to the troposphere, and they just drop out of the equation. When water condenses or there is a down draft (to match a rising thermal elsewhere), the energy is converted back to heat, which warms the surface, enabling it to radiate more Wm/2 again. There is no one-way transfer from surface to atmosphere, the W/m2 disappear from the surface and re-appear at the surface when and where the condensation and down drafts happen.

2. There are at least three more or less mutually exclusive theories as to what happens when infra red radiation hits a 'greenhouse gas' molecule and the diagram mixes and matches. It can't do all three things at once, and none of them actually increases the amount of energy:

A. Absorption
Molecule briefly absorbs the photon which increases the molecule's kinetic energy; before it has time to re-emit the photon, it collides with an N2 or O2 molecule, and increases the kinetic energy of those. We are told that all warm objects emit infra red except N2 and O2, so they are stuck with the higher kinetic energy*. This leads to warming. Fine, we know you can warm things up by shining infra red at them, so this in isolation makes sense.

(* Which leads me to a different train of thought, if N2 and O2 can only warm up - conduction and convection from the surface - but never radiate infra red, how would they ever cool down, even at the top of the atmosphere? If you think this through, the atmosphere would actually be a lot warmer than it is if it had no 'greenhouse gases'. Which is almost certainly nonsense, but shows up the theory to be nonsense as well.)

But, as with the conversion from actual heat to latent heat or potential energy, conversion from infra red radiation to heat takes those W/m2 out of the equation and parks the energy sideways in a different equation (same as latent heat, potential energy or trees). Temperature is measured in K, not in W/m2.

The diagram does not take this into account, so it actually shows no warming effect.

B. Scattering or re-radiation
The molecule absorbs and re-emits the infra red photon, so it scatters it or re-radiates it at random in all directions. Fine, this also makes sense in isolation.

If you start with a random photon somewhere in the troposphere moving in a random direction, you know that there are slightly more molecules per unit volume beneath it than above it. Therefore - you would reasonably assume - it is ever so slightly more likely that it will be bounced upwards by a molecule below it than being bounced downwards by a molecule above it.

Analogy - in the pub, people crowd round the bar. You are standing quietly drinking your pint. If you move away from anybody who jostles you, you will end up at the other side of the room. But I don't know how to adjust for this - the atmosphere is radiating a total of 199 W/m2 to space, so let's assume it is also radiating 199 W/m2 back to the surface.

C. Reflection
The theory appears to be that the molecule reflects the infra red photon directly back down again, the same way that is gets noticeably warmer (and slightly brighter, if you are in a back-lit urban area) on a clear night when a large thick cloud passes you at the right altitude.

This seems the least plausible theory.

But the diagram relies heavily on the theory of reflection. Out of the 332 W/m2 'back radiation', 199 W/m2 can be explained by theory B. above, meaning the average extra 133 W/m2 must be reflected - it is the only way to reconcile their figures.

It's worse when you dis-aggregate it into day/night: by day, the atmosphere is reflecting 13% straight back down, which seems just about plausible. But at night, the atmosphere is reflecting 45% straight back down, which is clearly nonsense.

Put the two together, and that's why they show an ugly grey band of 'greenhouse gases' at cloud level which appears to bounce 85% of the radiation from the surface straight back down again.

3. But never mind, I'm assuming that enough of their numbers are honestly and accurately measured or calculated for my version to be plausible - at least on their terms. I have used their figures as far as possible, but I had to change thermals from 17 W/m2 to 31 W/m2.

If the table looks a bit blurry, click it to see it clearly.


Graeme said...

You would do better to ask Sooty than a climate scientist. Actually, since they must be living easy at the moment, why not email someone at CRU or one of those places that teach climate astrology?

Mark Wadsworth said...

G, climate scientists don't answer questions. You might as well talk to a brick.

Dinero said...
This comment has been removed by the author.
Dinero said...

On the Ipcc diagram What is the physical meaning of 333 circulating between ground and atmosphere when the total radiation going into the ground and atmosphere is a figure that is less than that , 237

Mark Wadsworth said...

Din, your guess is as good as mine.

Mark Wadsworth said...

Din, I see what you mean. I have re-written part 2 to explain that they use a weird mix of theory B and C, while their actual intention was to show theory A.

Bayard said...

"We are told that all warm objects emit infra red except N2 and O2,"

Is this actually observed behaviour, or is it one of the six impossible things you have to believe before breakfast before becoming a follower of this particular religion?

Mark Wadsworth said...

B, in the good old days, scientists used to measure IR emitted by N2 and O2. There are official figures. But they stopped doing that because it didn't fit the script.