2 days ago, Sven Groot wrote
That's because there is no heat flow from cold to hot! A little bit of radiation goes that way, but the overall heat flow is still from hot to cold, just slower! If you think that's not allowed, give me a source, any source, that states that's what the second law means. Give me any source that says "photons are completely prohibited to travel from a low energy object in the direction of a higher energy object". I can't find any. By contrast, here's a source that supports my position:
I've always claimed in this thread and in the previous, that this was exactly the case. But not just for warming, also for cooling. Mass creates a slowness in the system. It's not due to the composition of the atmosphere, but due to it's mass. Also the mass explains what the average temperature on earth's surface should be, not some radiation balance sheet.
(Emphasis theirs) They use the description "sole result" rather than the word net, but it's the same thing. No one who understands both thermodynamics and the greenhouse effect would claim that its sole result is the transfer of hear from a cooler to a hotter body.
You misunderstand the context of the word sole, it's used in the form of; only. The only result can be from hot to cold,.
Without additional work, heat cannot flow from cold to hot. For instance a compressor in a fridge, then heat will flow from cold to hot, when it's forced by the compressor.
Try this one:
We have a brick, let's call it brick A, with a temperature of 30C. We place it in a vacuum, isolated from anything else. This brick radiates infra-red in all directions, right?
Now we place a second brick, brick B, with a temperature of 10C, next to it. The radiation of brick A reaches brick B, right?
Now we place a third brick, brick C, with a temperature of 50C, next to brick A. According to you, the radiation of brick A somehow does not reach brick C. Which process or force is stopping the radiation from reaching it? And don't say it's because of the second law: the second law is a description of what happens, not why it happens. I'm asking you what is physically blocking the radiation from going that direction after brick C was added.
No, no heat from brick A, radiation flows freely. Heat is absorbed radiation turned into work. I'm sorry if I confused you in the past comments. Radiation flows freely, but radiation will not get absorbed and add additional heat. You are quite right that the rate off energy loss will change when you introduce new bricks and that they will transfer heat to one another, till a stable situation is reached (till they are all the same temperature, regardless of type of material or mass).
What actually happens is that the radiation from brick A does reach brick C, and therefore brick C does receive energy from A. However, because brick C was already at a higher temperature, it loses energy itself at a higher rate than brick A, and brick A receives more energy from brick C than it's radiating. Therefore, the actual flow of heat is still from C to A. That's the same thing that happens with the back radiation in the greenhouse effect.
No, there you are just plain wrong.
Let's say radiation does reach the brick. The brick is vibrating at a higher frequency (as the sun is relative to our earth, that's why we absorb them and release a lower wavelength of light, this is discussed in describing entropy). The incoming photons vibrate at a lower frequency. So in order to absorb the photon, the brick first must speed the photon up to it's own frequency. Where is this energy coming from? The brick would have use it's own energy to speed up the incoming photon, in order to absorb it. Using your own energy will decrease the vibration of the brick and it will cool down. So either they drain energy or do not get absorbed at all, they clearly cannot add energy.
You can perform this thought experiment;
I run two identical tires at different speeds. I run one tire up to 15 kph and the other to 25 kph. I rotate them both anti clockwise. If I put the two tires in contact with one another, it's folly to claim that the 15 kph tire will add energy to the 25kph tire. Kinetic energy went from the 25 kph tire to the 15 kph tire and they are both now rotating at 20kph.
There is no positive flow of heat from A to C, it's impossible. Radiation? Yes,. Absorption? Maybe,.. Raising the temperature? Hell no.,. Heat flows from C to A.
You cannot decrease entropy without performing additional work. That's what the second law is all about, none of this net or sole mumbo jumbo.
Show me where in the climate system this additional work is taking place, then we can discuss the back radiation.