Tuesday, 11 August 2020

Daily energy budget for 1 m2 dry land

This has taken me several months to understand and work out, but here it is. The total of the three main forms of energy in the atmosphere above every 1 m2 of dry land, the thermal energy stored rocks/soil that warm up and cool down every day is in the order of 3.5 billion (to the nearest half a billion).

That dwarfs the incoming solar radiation of 21 million Joules, or the net 10.5 million Joules which are absorbed every day and re-emitted again every night. The daily "flow" is 0.3% of the total "stock".

Click to enlarge:

This whole exercise was prompted by the IPCC 'global energy budget' which is a) flawed at worst and b) misleading at best.

a) The most obvious flaw is averaging incoming radiation over a 24-hour period rather than splitting it up and doing two charts, one for the 12 hours of the day (all the radiation) and one for 12 hours of the night (none of it). Average surface temperatures are largely dictated by peak day time incoming radiation - Earth rotates quite fast so it doesn't have time to cool down much at night.

b) So they then mislead by sticking in a balancing figure for extra "back radiation" plucked - almost literally - out of thin air to boost day time temperatures back up to what they actually are (or would be, had they not stripped out half of day time solar radiation by the crude averaging).


James Higham said...

Insane amount of work, Mark.

Mark Wadsworth said...

JH, thanks, yes it was.

Like everything, "it's easy when you know how", it's the working out "how" which is tricky.

Why isn't this type of chart the first thing you find when you Google it? You have to piece it all together slowly and painfully from dozens of different sources.

Dinero said...

Looks OK except do you not want to include any heating from the warm atmosphere at all , Infra Red radiated from the atmosphere towards the ground. There is the Gravity induced lapse rate , but also water vapour heats up and radiates IR towards the ground warming the ground , or do you not think so.

Mark Wadsworth said...

Din, can we get away from this IR nonsense?

The ground and the air/water droplets are at a similar temperature, there is little to no IR radiation between things of a similar temperature. That way lies madness and double-counting.

The only source of energy (in all its forms) is the Sun and the only place it can escape to is space. That must in the form of radiation (UV, vis, IR). The atmosphere is not a source of energy to heat the air (or vice versa). They don't heat each other! The Sun heats them both!!

Dinero said...

" there is little to no IR radiation between things of a similar temperature"
The amount of IR is not dependent on the temperatures of the things. Warm objects emit IR.
The physics of how an absorber/emitter heats up with a given amount of incoming radiation does not include the presence of an adjacent absorber/ emitter receiving the emitted IR and re-radiating it, therefore the IR that does come from from a secondary absorber/emitter has to be included as an extra source in the calculation of temperature.

Mark Wadsworth said...

Din, nope.

Take a large red-hot glowing log from the fire. It is clearly emitting IR.

Chop it in two and put the pieces near each other, do they become even hotter because they are radiating at each other?

Chop each piece into two and you have four objects emitting IR at each other. Do they then become even hotter again?

The answer to both questions is a hard "no" (if you adjust for more surface area = more oxygen = burns a bit better, but for a shorter time).

This is one of the IPCC's tricks - chopping up the atmosphere into horizontal chunks and pretending that they are all radiating at each and heating each other up.

IR is just another form of energy, or a particular manifestation of thermal energy.

Dinero said...

As I have said before Analogy is the enemy of science. The two half logs still obey the physics of radiation and heat and so they do not get any hotter. The heat equation for an absorber / emitter includes the re-radiation of the subject object but does not include back radiation from an adjacent object and so the back radiation where it is precent has to be included an an additional term in the heat calculation.

Robin Smith said...

Did you check into Prof. David Mackay's calculations from his book 'Energy Without the Hit Air' 10 years back?

Dinero said...

> Mark

I am going to look into this, the physics of heat between a source and what it heats , I am open mined about it at the moment.

Dinero said...

My description above is my take on what the IPCC seem to be saying and I am not saying it is correct.

Are you saying that for the purpose of heat, the surface and the atmosphere are all one body with a gradient going hot ground to cool troposphere and that is it, there no back heating in the other direction.

Mark Wadsworth said...

Din: "Are you saying that for the purpose of heat, the surface and the atmosphere are all one body with a gradient going hot ground to cool troposphere and that is it, there no back heating in the other direction?"

Yes, that is exactly what I am saying.

Imagine it like a pan full of hot water. It's one thing in equilibrium.

Once you take it off the stove, the pan is not warming the water and the water is not warming the pan. They start the same temperature and cool down at same speed (even though metal has quite different properties to water).

Robin Smith said...

Truth, in a world where facts no longer matter.

Come on guys this is so irrelevant. You can't change people's religion.

Why not focus on the far more interesting black women soon to be president

Robin Smith said...

Facts, in a world where truth no longer matters.

You've been doing this for decades. I know ancient men who've been doing it all their lives, are bitterly unfulfilled and their grand children do not respect them. Not to mention their sons and daughters.

When will you realise that all you have, are facts? And that facts are not what persuade people. Especially large groups of people.

LVT as a classic exposition of this denial.