Mainly by convection.
By convection and radiation.
Conduction, convection and radiation are the three modes of heat transfer.
Conduction is heat transfer through a solid (that does not apply in this case).
Convection is heat transfer through a liquid or gas, this applies and most heat will transfer this way.
Radiation is the only transfer mode that can move through a vacuum -- but some heat will still move through the atmosphere via this mode.
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Kano - I agree, for all practical purposes I'd say all the heat transfers within the troposphere by convection. The air molecules are pressed against each other. Barometric pressure is 14.7 pounds per square inch at sea level. So no heat, or almost no heat would ever transfer by radiation. It will convect.
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pegminer - Learn NOT to use stuff from the propaganda site SkepticalScience.com, the site where even it's name is a lie. Not only does that Energy Budget diagram NOT address the question, because it does not address how the energy moves. But the diagram is also outdated and WRONG. Even NASA has removed greenhouse gas back radiation from it's diagram of the earth's energy budget because it defies the 2ed Law of thermodynamics. Heat can NEVER move toward warmer. http://science-edu.larc.nasa.gov/EDDOCS/...
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Well, most of us see conduction, convection and radiation as the likely options. I find that quite reassuring!
Conduction: Likely to be minimal because air is a good insulator.
Radiation: Some IR radiation is not blocked by the GHGs so that will be able to leave the pinball machine that is planet earth without let or hindrance. Other IR radiation will encounter GHGs quite soon after leaving earth's surface and will excite the various vibration modes of ther GHGs which willl not be quick enough to re-emit so they will pass the heat to nearby non-GHG molecules by conduction. Some visible light must also escape otherwise wou would not be able to see the earth from space. I believe that most UV is blocked higher up causing heating at the top of the atmosphere.
Convection: This has to be the biggie in my view. The air warmed by the GHGs will convect as will any water vapour with its latent heat. Any air that does warm by conduction from the earth will also be able to convect.
It’s by all three processes.
The Earth radiates head out in a similar way to a fire or a radiator, this thermal radiation enters the atmosphere and heats all the different layers of it.
The atmosphere itself is fluid, it moves in similar ways to water in that it has currents, eddies and it swirls around. This movement of the air transports heat from Earth through convection.
There is also a small amount of conduction, although as you know, the air isn’t particularly conductive so there’s limited transport of heat by this method.
http://www.skepticalscience.com/pics/Fig...
EDIT for Maxx the Liar: You can get the same diagram from hundreds of sites and from Trenberth's paper. This was taken directly from a post by Trenberth. The energy budget diagram absolutely addresses the equation since it breaks down the energy flow into upward and downward components (your NASA diagram does not do that but instead looks at the net flow). Your idea that it defies the second law is laughable. It's too bad that Planck is not alive for you to inform him that his radiation law is in conflict with his formulation of the Second law.
EDIT for Kano: 40 Wm-2 is what makes it through the entire atmosphere and out to space. 396 Wm-2 is what is emitted upward by the surface. Without the greenhouse effect from the atmosphere and clouds there would not be the 333 Wm-2 of back radiation.
Long wave radiation rises due to convection
All of the above. However, heat can only leave the planet through radiative processes.
Its because you left the damn door open.
Is it by conduction, convection or radiation.
