Wednesday, 15 July 2020

One of these explanations is correct; one is complete nonsense.

It is agreed that in the absence of gravity and 'Greenhouse Gases', Earth's atmosphere would be the same temperature (about 255K, or -18C) all the way up. (The air would have to be held in with a very thin Perspex sphere to stop it floating off into space):

What we actually observe is this temperature profile. Air is warmer lower down and cooler higher up (the average is pretty close to 255K):

[So the much vaunted 33C Greenhouse Effect is only at the surface, it's zero half-way up and negative at the top]

There are two competing explanations as to why this is (why the troposphere isn't 'isothermal' to use a fancy phrase).

From the late 1800s to the 1970s, it was explained using physics. You can explain it in layman's terms in a few sentences. Or you can go on for several hundred pages with endless equations and invoke Ideal Gas Laws, quantum physics at sub-molecular level, concepts like entropy, enthalpy and The Second Law of Thermodynamics. See links in widget 'Gravity and the Greenhouse Effect' in the side bar.

That's all unnecessary for real life purposes. What it boils down is that total energy (thermal energy + potential energy) is the same all the way up. PE must be highest at the top and zero at sea level. While PE adds to total energy, it doesn't increase total thermal energy, it just displaces it from high up to low down. Whether the atmosphere contains 'Greenhouse Gases' or not is entirely irrelevant because they make no difference (except to the extent that their molecular mass and specific heat capacities are different to those of N2 and O2). Of course, you don't measure potential energy in degrees K, but this is just to illustrate the principle:

This has been airbrushed out of mainstream teaching since the 1980s. They don't even mention it as a flawed and superseded theory (like the geocentric model of the solar system or the aether).

The common explanation nowadays is that 'Greenhouse Gases' trap thermal energy lower down and increase the amount of energy radiated from higher up, hence the lapse rate:

These two explanations are mutually exclusive. There is no mix and match. It's either one or t'other. Either you accept that the atmosphere is shaped by gravity and that temperature, pressure and density decline as you go up to balance out total energy (interesting but not very exciting); or you believe that a gas which makes up 0.04% of the atmosphere does all this.

There are even people at the more moderate end of the Warmenist spectrum (Clive Best or Roy Spencer) who insist that there has to be both gravity AND 'Greenhouse Gases' for there to be a lapse rate. Go figure.

Had the Warmenists refined the old explanation and split it into "mainly due to gravity" and "a bit more due to due to CO2 and methane" (as some of them do, to be fair), this would be 'at least plausible' and would not have aroused the suspicions of the layman:

But they are claiming the whole 33C for themselves and even worse, they usually gloss over the fact this is only true at sea level. They went all-or-nothing and have lost. This is why I have shifted from Skeptic to flat-out Denier.


Lola said...

I don't trust governments. Hence it's nice to see my prejudice that MMGW is a scam, is confirmed.

Mark Wadsworth said...

L, on balance, it looks like an absolute scam, doesn't it? Proper physics professors who do boring stuff like explain gravity (and yes it is boring in a nice safe way) got completely side lined from the 1980s onwards. They weren't geared up for political counter-campaigning, they have all retired, and the next cohort knows to keep their mouths shut or lose their jobs.

Andrew Carey said...

Has this been verified at the level of the garden greenhouse? I'm not going to run the experiment myself, but if I add say Chlorine gas to my greenhouse will it raise the temperature by a greater amount than if I add nothing and it just displaces nitrogen. Will propane with its four carbons and higher molecular weight increase the temperature by more than adding CO2?

Bayard said...

AC, the answer is yes, but you couldn't possibly afford instruments sensitive enough to measure the difference, even such instruments exist.

Mark Wadsworth said...

AC, B has given you the same answer I would have given you.

Lola said...

MW et al. The analogy I have with MMGW is the medieval catholic church selling indulgences. It's all about power, control and extortion. People like St Greta are the Leninist 'useful idiots'. And other enforcers of the faith are analogous to commissars.

This is the perennial battle. in fact the only battle that matters, between the Common Man and the latent rent seeking extractive class. Or as they were called in an earlier time, our elders and betters.

Bollocks to the lot of them I say.

Mark Wadsworth said...

L, ultimately yes. That's one of Bayard's themes. Climate denier in chief Joseph Postma has a separate blog category for The Religion of Climate Change.

BTW, Greta is Joan of Arc.

Lola said...

Joseph has stolen my criticism. The world is drowning in sophistry.

ontheotherhand said...

What hope have we got to understand when the BBC runs stories like this? What is the 'hook' for the story? A new research paper or something? No. Who are they quoting "too hot for humans" from?

Mark Wadsworth said...

OTOH, that one is an absolute classic of Climate Porn. They interview the man wearing the hottest clothing in the hottest building in one of the hottest countries, and he moans about how hot he is. Wow.

Bayard said...

"This is the perennial battle. in fact the only battle that matters, between the Common Man and the latent rent seeking extractive class."

The class struggle makes much more sense when you put it that way, as the struggle between the Productive Classes and the Extractive Classes, a much more accurate division than, say, Capital and Workers.

Mark Wadsworth said...

B, "the struggle between the Productive Classes and the Extractive Classes, a much more accurate division than, say, Capital and Workers"

Owners of proper productive capital, workers and consumers are all on the same side, with the same basic goal (to consume as much as possible for as little human effort as possible) and are ultimately the same thing.