Chill!

[MacG]

So you are telling me that the greenhouse effect is not the explanation for the very high surface temperature of Venus, and your reason is that Venus shines brightly because it reflects a lot of sunlight. This tells me that you don't know what the greenhouse effect is - that you do not understand the chemistry and physics behind the mechanism. Before I go on, would you please confirm that this is the case?

You made a claim about the cause of the conditions on Venus, I asked for some support for that claim.

No, MacG, I actually asked you a question. This one:

Are you trying to suggest that the greenhouse effect doesn't exist? (i.e. that this is not the explanation for the surface temperature of Venus?

You did not quite say "yes", but your answer certainly implied "maybe." I then asked you another question, which you haven't answered. This one:

This tells me that you don't know what the greenhouse effect is - that you do not understand the chemistry and physics behind the mechanism. Before I go on, would you please confirm that this is the case?

I am asking you whether or not you believe you understand the basic chemistry and physics underlying the theory of the greenhouse effect on planetary climate systems. I strongly suspect you do not, but I am waiting for you to answer the question. Trying to put the ball back in my court by asking me to support the implied claim that the greenhouse effect is real (i.e. that the physics and chemistry in question is sound, and the GE is the correct scientific explanation for the surface temperature of venus) will not work. I could explain this physics and chemistry to you if I wanted to, but I first want to give you an opportunity to tell us what you believe your own current state of knowledge to be.

Just to make this crystal clear: I want you either to admit you do not know what you are talking about (scientifically) or commit yourself to the claim that you do already understand the science and that you think there is something wrong with it. Your move.

Sorry, your lack of content can not be compensated by an overload of words. It is you who know nothing about the climate on Venus. I let this stand for the bypassers to look at.

[UndercoverElephant]

You made a claim about the cause of the conditions on Venus, I asked for some support for that claim.

No, MacG, I actually asked you a question. This one:

Are you trying to suggest that the greenhouse effect doesn't exist? (i.e. that this is not the explanation for the surface temperature of Venus?

You did not quite say "yes", but your answer certainly implied "maybe." I then asked you another question, which you haven't answered. This one:

This tells me that you don't know what the greenhouse effect is - that you do not understand the chemistry and physics behind the mechanism. Before I go on, would you please confirm that this is the case?

I am asking you whether or not you believe you understand the basic chemistry and physics underlying the theory of the greenhouse effect on planetary climate systems. I strongly suspect you do not, but I am waiting for you to answer the question. Trying to put the ball back in my court by asking me to support the implied claim that the greenhouse effect is real (i.e. that the physics and chemistry in question is sound, and the GE is the correct scientific explanation for the surface temperature of venus) will not work. I could explain this physics and chemistry to you if I wanted to, but I first want to give you an opportunity to tell us what you believe your own current state of knowledge to be.

Just to make this crystal clear: I want you either to admit you do not know what you are talking about (scientifically) or commit yourself to the claim that you do already understand the science and that you think there is something wrong with it. Your move.

Sorry, your lack of content can not be compensated by an overload of words. It is you who know nothing about the climate on Venus. I let this stand for the bypassers to look at.

Ah. So you aren't willing to answer the question "Do you understand the basic science behind the greenhouse effect?"

I think that will tell passers-by everything they need to know about the value of MacG's opinions on climate change. If you answer "no", then you've admitted your opinion isn't based on science. If you answer "yes" then you're going to have to explain what is wrong with the scientific explanation for the atmospheric conditions on Venus.

Rock ->> MacG <<- Hard Place

[kenneal - lagger]

My understanding of the Venusian climate is that it should have a very hot side, facing the sun, and a very cold side, facing away from the sun. The fact that it has a very even temperature all over is because the very high level of carbon dioxide in the atmosphere retains much of the heat produced by the sun, evening out the temperature between the sun exposed side and the dark side.

The Wikipedia reason for mercury's brightness http://en.wikipedia.org/wiki/Phase_curv ... tronomy%29) is below together with the references to the scientific papers MacG wanted. I must admit that I don't know what it means. Perhaps Candy can explain.

Venus
Alternative text
The phase curve of Venus[15] compared to Mercury[1], and the brightness excess of Venus.

The relatively flat phase curve of Venus is characteristic of a cloudy planet[14]. In contrast to Mercury where the curve is strongly peaked approaching phase angle zero (full phase) that of Venus is rounded. The wide illumination scattering angle of clouds, as opposed to the narrower scattering of regolith, causes this flattening of the phase curve. Venus exhibits a brightness surge near phase angle 170°, when it is a thin crescent, due to forward scattering of sunlight by droplets of sulfuric acid that are above the planet’s cloud tops[15]. Even beyond 170° the brightness does not decline very steeply.

The history of observation and analysis of the phase curve of Venus is similar to that of Mercury. The best set of modern observations and interpretation was reported by A. Mallama, D. Wang and R. Howard[15]. They used the LASCO instrument on SOHO and ground based CCD equipment to observe the phase curve from 2 to 179°. As with Mercury, these new data are the major source of the phase curve used in the Astronomical Almanac[13] for predicting apparent magnitudes.

In contrast to Mercury the apparent brightness of Venus as seen from Earth does not occur at phase angle zero. Since the phase curve of Venus is relatively flat while its distance from the Earth can vary greatly, maximum brightness occurs when the planet is a crescent, at phase angle 125°, at which time Venus can be as bright as magnitude -4.9[14]. Near inferior conjunction the planet typically fades to about magnitude -3[14] although the exact values depends on the phase angle. The typical range in apparent brightness for Venus over the course of one apparition is less than a factor of 10 or merely 1% that of Mercury.

13 a b Hilton, J.L. (2005). "Improving the visual magnitudes of the planets in the Astronomical Almanac. I. Mercury and Venus". Astron. J. 129: 2902-2906.
14 a b c d e f g h i Mallama, A. (2011). "Planetary magnitudes". Sky and Telescope 121(1): 51-56.
15 a b c Mallama, A.; Wang, D.; Howard, R.A. (2006). "Venus phase function and forward scattering from H2SO4". Icarus 182: 10–22. doi:10.1016/j.icarus.2005.12.014.

It does mention that Venus has a cloudy atmosphere with sulphur dioxide at high level which reflects sunlight. This might suggest that Venus should be cool. But Venus is much closer to the sun than we are and so the sun's radiation is more intense. Also given the high insulation value of the Venusian atmosphere, the planet can reflect a much greater proportion of the incident radiation and still maintain a much higher temperature than earth.

Got any arguments with that, MacG?

[UndercoverElephant]

double post

[UndercoverElephant]

That Venus argument is pretty annoying.

Not for me it isn't.

Do you have ANY support for assuming that some "greenhouse effect" is responsible for the environment on Venus? Could you in that case explain why Venus is so bright? Is it because it absorbs so much sunlight???

"Why is Venus so bright?" is a shortened version of "Why is Venus so much brighter than most of the other objects in the sky?" And the answers are:

(1) It is close to the Earth, often very close.
(2) It is close to the Sun, which is the source of the light.
(3) It has thick clouds which reflect a lot (70%) of the visible electro-magnetic waves which reach it from the sun.

What does this have to do with the Greenhouse effect? Absolutely nothing. The greenhouse effect is this:

Step #1) visible light (and other EM radiation) enters the atmosphere of a planet
Step #2) it heats up material in the atmosphere and on the ground
Step #3) this heat is then re-emitted at non-visible infra-red wavelenghts
Step #4) light at these long wavelengths interacts with greenhouse gases and so rather than escaping back into space, is trapped inside the atmosphere.

Now ask yourself the following question: Does it make any difference to the existence of the greenhouse effect whether the amount of visible light reflected is 20%, 50% or 80%? The answer is NO, MacG. Altering the amount of visible light which initially enters the atmosphere makes a difference to how quickly the Greenhouse effect operates, but it makes no difference at all to whether or not it exists. Even if only 1% of the visible light gets through, a "greenhouse super-blanket", such as exists on Venus, will still be operating.

[PS_RalphW]

This discussion reminds me of my daughter when she 'goes reptilian' to use a technical term. (As she did at 8am this morning).

It is when the higher functioning areas of the brain (the prefrontal cortex and all) are locked out as the lower (evolutionary reptilian) brain takes over due to excessive stress hormones. Further reasoning becomes impossible until the hormone balance is restored.

In my daughter's case every attempt at reasoning is thrown back with flat contradiction, even if that contradiction is itself a direct contradiction of her previous utterance.

This morning I had to man handle her, without coat or shoes, into the car. Sans breakfast, for my wife to get her to school. Of course, if we had got two mouthfuls into her, the sugar rush would have restored her to sweetness and light in 30 seconds.

It is a transformation you wouldn't believe until you see it yourself.

[biffvernon]

From here you can do you own leg work.

At that point, this morning, I tried to find a google image for legless troll but there didn't seem to be a suitable one. Maybe MacG is the first.
Anyway, I spent the afternoon doing something more useful.

However, reading through MacG's nonsense at least roused my curiosity regarding the albedo of Venus. Here's what I found:

Albedo is a measurement of the reflectivity of an object. A theoretically perfect reflecting object would have an albedo of 1, and reflect 100% of the electromagnetic radiation that falls upon it. While an object that was perfectly black and doesn’t reflect any light would have an albedo of 0. In real life, objects in the Solar System have albedo values between 0 and 1. And in the case of Venus, the albedo is 0.75.

Just for comparison, the bond albedo of the Moon is only 0.12. That’s actually pretty dark. The brightest albedo in the Solar System is Saturn‘s moon Enceladus, with an albedo of 0.99. It reflects almost all of the light that falls onto it.

One of the reasons that Venus is so bright in the sky is because of its high albedo. This albedo comes from the permanent cloud layer that surround the planet. These clouds are made up of sulfuric acid that reflect much of the radiation that falls upon them.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to NASA’s World Book on Venus, and here’s NASA’s Solar System Exploration Guide to Venus.

Of course it was James Hansen who did the main work on the atmosphere of Venus, early in his scientific career, before he turned his attention towards Earth climate science. In his recent book, Storms of my Grandchildren, he concludes that if we burn all the oil and the coal and the oil shales and the tar sands then we will end up wit a climate similar to Venus.

It kinda emphasises the importance of saving the planet.

[emordnilap]

Dear Sir,

Could you consider lowering yourself to such a level that you provide a link to the climate models used by the IPCC? Not a blog, please, but a real peer reviewed journal. I have access to all library services needed to retreive a copy if you just provide a reference.

Sincerely

Dear sir/madam

Could you consider lowering yourself to such a level that you search the web, starting (just two suggestions, to help you out) here and here?

Why not get in touch with the IPCC, if you have some sort of dispute with them?

Faithfully.

Naughty boy! That was Wikipedia and Google. Not quite a peer reviewed paper.

Of course not.

[Blue Peter]

Of course, if we had got two mouthfuls into her, the sugar rush would have restored her to sweetness and light in 30 seconds.

It is a transformation you wouldn't believe until you see it yourself.

We see something similar (but perhaps not quite as extreme) with our elder son. Of course, one of the "flat contradictions" is that they won't eat, even though they need to (and possibly want to). Plates with biscuits on have been left, so that they can be taken without being seen to be forcing food onto him.

Though we fear that our attempts to keep blood sugar level up (equals being keen to offer food at most occasions) may lead (is leading to) weight issues,


Peter.

[emordnilap]

I let this stand for the bypassers to look at.

A-ha. Code for "I'm in a hole. I'll stop digging."

[JohnB]

I let this stand for the bypassers to look at.

A-ha. Code for "I'm in a hole. I'll stop digging."

Or he gets his information from Fux News, and has been shocked by this revelation
http://www.guardian.co.uk/media/2010/de ... ange-email

[MacG]

I let this stand for the bypassers to look at.

A-ha. Code for "I'm in a hole. I'll stop digging."

Or he gets his information from Fux News, and has been shocked by this revelation
http://www.guardian.co.uk/media/2010/de ... ange-email

Uh.. "exhausted" and "bored" is more relevant. Look, I want do discuss the (in)accuracy of the IPCC computer simulations, but are faced with a complete mess of assumptions. Including Fox News which I have never watched more than 3-4 seconds in a row.

[clv101]

A-ha. Code for "I'm in a hole. I'll stop digging."

Or he gets his information from Fux News, and has been shocked by this revelation
http://www.guardian.co.uk/media/2010/de ... ange-email

Uh.. "exhausted" and "bored" is more relevant. Look, I want do discuss the (in)accuracy of the IPCC computer simulations, but are faced with a complete mess of assumptions. Including Fox News which I have never watched more than 3-4 seconds in a row.

In case you haven't realised yet, there are no GCM developers posting on PowerSwitch. If you really are interested in how the models work I suggest (as I have a couple of time before) you take up your concerns with the people responsible directly, or at the very least find an online community where model developers do post.

[MacG]

Or he gets his information from Fux News, and has been shocked by this revelation
http://www.guardian.co.uk/media/2010/de ... ange-email

Uh.. "exhausted" and "bored" is more relevant. Look, I want do discuss the (in)accuracy of the IPCC computer simulations, but are faced with a complete mess of assumptions. Including Fox News which I have never watched more than 3-4 seconds in a row.

In case you haven't realised yet, there are no GCM developers posting on PowerSwitch. If you really are interested in how the models work I suggest (as I have a couple of time before) you take up your concerns with the people responsible directly, or at the very least find an online community where model developers do post.

I merely find it interesting that people can show such an agressive mob behaviour over an issue they dont have any deeper insights in.

[caspian]

In case you haven't realised yet, there are no GCM developers posting on PowerSwitch. If you really are interested in how the models work I suggest (as I have a couple of time before) you take up your concerns with the people responsible directly, or at the very least find an online community where model developers do post.

But he's not really interested in the models at all. He's just trying to wind us up. Much like a TROLL in fact.