Why atmospheric MASS, not radiation? Part 2

Be sure to read Part 1 first, now …



DEFINING THE rGHE THROUGH THE ERL.

How is the rGHE defined in the most basic way? If you have a planet with a massive atmosphere, the strength of its “greenhouse effect” is defined as the difference between its apparent planetary temperature in space and the physical mean global temperature of its actual, solid surface. The planet’s apparent temperature in space is derived simply from its average radiant flux to space, not from any real measured temperature. It is assumed that the planet is in relative radiative equilibrium with its sun, so is – over a certain cycle – radiating out the same total amount of energy as it absorbs.

If we apply this definition to Venus, we find that the strength of its rGHE is [737-232=] 505 K. Earth’s is [288-255=] 33 K.

The averaged planetary flux to space is conceptually seen as originating from a hypothetical blackbody “surface” or ‘radiating level’ somewhere inside the planetary system, tied specifically to a calculated emission temperature. This level can be viewed as the ‘average depth of upward radiation’ or the ‘apparent emitting surface’ of the planet as seen from space. Normally it is termed the ERL (‘effective radiating level’) or EEH (‘effective emission height’).

The idea behind the ERL is pretty straightforward, but does it accord with reality? The apparent planetary temperature of Venus in space is 231-232K, based on its average radiant flux, 163 W/m2. Likewise, Earth’s apparent planetary temperature in space is 255K, from its mean flux of 239 W/m2. In both of these cases, the planetary output is assumed to match its input (from the Sun), so one ‘simple’ method one could use to derive the apparent temperature of a planet is by taking the TSI (“solar constant”) at the planet’s (or moon’s) particular distance from the Sun, and multiply it with 1 – α, its estimated global (Bond) albedo, a number that’s always <1, finally dividing by 4 to cover the whole spherical surface. Determining the average global albedo is clearly the main challenge when going by this method. The most common value provided for Venus is 0.75, for Earth 0.296.

But does the resulting value really say anything about the actual planetary temperature? If the planet absorbs a mean radiant flux (net SW) below its ToA, then how this flux affects the overall system temperature very much depends on the system’s total bulk heat capacity. If it is large, the flux will have little effect, if it’s small, the flux will have a bigger effect.

Continue reading

‘To heat a planetary surface’ for dummies; Part 3

We’re still discussing Willis Eschenbach’s ‘Steel Greenhouse’.

How come the warming EFFECT of putting the shell around the sphere is real but Eschenbach’s “back radiation” EXPLANATION of how it comes about is wrong?

Simply put, it’s because the effect doesn’t violate the 2nd Law of Thermodynamics, but the explanation does.

In Part 1 and Part 2 we established some fairly basic principles of thermodynamics that we can now put to use in analysing Eschenbach’s explanation of why and how the radiating central sphere needs to warm with the steel shell surrounding it:

“In order to maintain its thermal equilibrium, the whole system must still [after the steel shell is placed around the sphere] radiate 235 W/m2 out to space. To do this, the steel shell must warm until it is radiating at 235 watts per square metre. Of course, since a shell has an inside and an outside, it will also radiate 235 watts inward to the planet. The planet is now being heated by 235 W/m2 of energy from the interior, and 235 W/m2 from the shell. This will warm the planetary surface until it reaches a temperature of 470 watts per square metre. In vacuum conditions as described, this would be a perfect greenhouse, with no losses of any kind.”

The first part of this paragraph simply describes the necessary conditions for reaching a new dynamic equilibrium upon putting the steel shell up around the radiating sphere. Nothing mysterious about it at all.

But then (in the bolded part) Eschenbach starts ‘explaining’ how he sees this new state of dynamic equilibrium to be accomplished.

And this is where any connection to basic, ordinary physics – and hence, to the real world – appears to be lost.

Let’s parse what he’s saying: Continue reading

Postma’s confusion

This could hopefully be a nice learning experience as part of our ongoing discussion on ‘how to heat a planetary surface’.

I went over to Joseph Postma’s site to see how they treat the whole sphere/shell problem there, having learned that some commenter had linked to my last post on the subject on one of his threads, evidently leading to the appearance soon after of a couple of climateofsophistry.com regulars on this blog.

What I found quite frankly appalled me.

It is just as much a cultic echo chamber as any warmist site I’ve ever visited. They live firmly and tightly packed inside their little pink bubble, completely detached from reality, but keep patting each other on the back, congratulating themselves whenever more elaborate ways are found to consolidate and entrench the cult’s profoundly absurd ideas about the world, loudly and indiscriminately thrashing everyone not agreeing with them, calling them idiots, criminals and the like. Anyone who dares question the dogma is immediately and summarily labelled a ‘sophist’. The cult leader, Postma himself, is of course first in line, the worst of the lot, a person with clear megalomaniacal tendencies, whose modus operandi when it comes to meeting a challenge consistently revolves around twisting the opponent’s every word, nitpicking on irrelevant semantic details to evade major points being made, constantly ‘misunderstanding’ opposing arguments, thus creating the opportunity to divert and build straw men to tear down, all of it sprinkled with a nice dose of mockery and verbal abuse.

In short, the perfect sophist, surely a dedicated student of the Alinsky method.

Following are a couple of exchanges from Postma’s blog exemplifying precisely what I mean, highlighting the blinkered, confused nature of Postma’s world view, plus his aggressive rhetorical tactics employed whenever he needs to escape rational – but obviously uncomfortable – counter-arguments threatening to trap and expose him, keeping his flock’s cognitive dissonance safely at bay: Continue reading

‘To heat a planetary surface’ for dummies; Part 2

For something – anything – to acquire a temperature above absolute zero (0 K), it somehow needs to be able to warm. The only real requirement for something to be able to warm is for it to possess a ‘thermal mass’, or simply ‘mass’. A thermal mass provides the thing in question with what is (a bit awkwardly) called a ‘heat capacity’, meaning a capacity to absorb and store energy from some energy source (external or internal).

We already know, from basic thermodynamic principles, how energy can be transferred to (or from) an object. It can be transferred in the form of ‘heat’ [Q] or in the form of ‘work’ [W]. Whenever energy is transferred to an object, the ‘internal energy’ [U] of that object increases as a result, which simply means that the object in question has absorbed (energy isn’t ‘transferred’ to a system until it’s actually become ‘absorbed’ by it) the energy to store it inside its mass, as microscopic kinetic and potential energy of its atoms and molecules.

We already know, from the first post in this series, how system ‘internal energy’ [U] relates to system ‘temperature’ [T]. We know that a system with a high ‘heat capacity’ will warm more slowly than a system with a low ‘heat capacity’, both systems absorbing equal energy inputs, the high-heat-capacity system simply storing a larger portion of the absorbed energy as internal/molecular PE rather than as internal/molecular KE (determining the temperature). Both systems, however, will warm, only at different rates. U and T invariably move in the same direction. Unless there is an ongoing phase transition. Then U will increase and T will not. There is no process, though, where U increases and T decreases. The two correspond.

OK. We know that to make an object warm, we must make it accumulate ‘internal energy’. If it doesn’t, it cannot warm. Continue reading