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Frequently Made Errors in Climate Science - The Greenhouse Effect - Comments
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[QUOTE="Bandersnatch, post: 5517929, member: 399360"] Sorry for the late response to my part of the conversation. I didn't want to make this a wall of quotes (and kinda hoped haruspex would take over my bit as well), but I couldn't figure out any other way to go about it. I'll try to summarise the crux of the issue as what I think it is first, and then address some of the particular misconceptions in the spoiler. The last sentence here seems to be the culprit here. You're seeing the atmosphere as an additional heat sink - i.e., the idea seems to be that since for a set amount of incoming radiation Z, surface radiates X energy to space, then if we add a medium that will remove extra Y energy from the surface, and carry it away where it will then escape into space, it should mean that we've added another sink, so that the energy escaping is X+Y, meaning the radiative emissions have to go down, meaning the equilibrium temperature at the surface must become lower. The issues with this picture are: - the atmosphere is for the most part not transparent to the outgoing radiation, so it can't just escape into space - it gets absorbed and reradiated in all directions, including downwards. The actual atmospheric window for escaping radiation is just about 40 W/m^2. - the thermal heat transfer (conduction, convection, evaporation) from the surface is 1. small when compared with radiative transfer, and 2. ends up being reradiated in upper parts of the atmosphere, again including back to the surface. This could still be a valid objection if the energy balance at the surface was a net removal of energy, and would require quantifying - if it hasn't been done many times already. E.g. see the following paper (with its inforgraphic reproduced below): [URL]http://journals.ametsoc.org/doi/pdf/10.1175/2008BAMS2634.1[/URL] [ATTACH=full]189084[/ATTACH] All that energy that was removed from the surface and then returned in the form of back radiation changes the energy balance at the surface so that there is more incoming energy Z, and the equilibrium has to change to increase radiation (or thermals, but their magnitude is secondary), meaning increase in temperature of the surface. So, looking at the atmosphere as a heat sink is faulty reasoning - it is an insulator. But all you really needed, in order to [I]know[/I] that the atmosphere is raising the surface temperature, is to do the calculations for the blackbody equilibrium temperature for an airless barren planet at 1 AU around the Sun. Since that is [U]lower[/U] than what we've got here, it is a clear indication that the atmosphere is responsible for [U]raising[/U] the temp. All that remains is to figure out how (which the paper linked above does nicely). I'll put the rest into spoilers, since it's all a bit tangent to the main issue, I believe. [spoiler] The Stefan-Boltzman law concerns only radiative energy transfer from a black body. You can't use it for thermals. No! The violation would be if there was colder atmosphere heating up hotter surface, whereas what we've got is the [I]hot Sun[/I] heating up the surface. When considering the Earth+atmosphere system, you don't get any NET heat flow inward. Heat is always flowing away from the hot source (surface) to colder surroundings (including space). But there is extra energy coming inward from the atmosphere that wouldn't be there without air, which means that the NET heat flow is lower and the equilibrium temperature at the surface has to self-adjust to re-emit that extra energy. You should forget everything you wrote about GR there and there on after, since it's completely misappropriated, and just wrong. Forget about the c^2 in the equation, it's confusing you. It's just a unit conversion factor, and you can freely choose units in which it's equal to 1, so that all the equation says is that mass of a body at rest has some associated energy. You're mostly talking about energy conservation anyway, which is not violated when putting CO2 into the atmosphere (because the mass was already there, only not in the atmosphere) nor when increasing temperature, because the system is not closed - i.e. the Sun provides energy. If you would design a rather implausibly good insulation system for the planet, you could raise its temperature as high as the temperature of the Sun's surface, and it wouldn't violate any conservation nor thermodynamic laws. And yes, that means that a hotter Earth has more energy stored, i.e., is more 'massive', i.e., curves space-time more. Why would CO2 on Earth heat the Sun? It doesn't make any sense. No, that is a tell-tale sign of a good insulator. This might be another significant issue - what you seem to consider 'cooling' is just heat transfer from hot to cold. Remember that we're talking about systems in thermal equilibrium with their surroundings, which include heat sinks and heat sources. In such a system there will always be temperature gradients, but this doesn't necessarily mean there is cooling. E.g. if you put on a sweater in winter, a steep gradient from your skin to the air will set up. By your usage of the term, the sweater is 'cooling' your skin, because you're loosing heat through it. For something to be cooling a body heated by an external source, it has to increase energy transfer from the body, so that more net heat is removed than without it, and the equilibrium temperature drops as a result. E.g., if you put a radiator on your processor, it'll remove more energy by increasing surface area in contact with air, reducing its temperature - i.e. a cooling effect. Conversely, if you glue a block of fibreglass to the processor, it'll slow down heat transfer, heating it up. The second case will have a steeper temp gradient than the first, but it will be undoubtedly heating. I might have skipped a few points, but this response is already way too bloated. [/spoiler] [/QUOTE]
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