What rate of speed does heat travel away from the earth?

Question

More specifically, IR travels at the speed of light, how much lag is caused by the atmosphere when greenhouse gases absorb and re-emit the energy?

Answer 1

In order to maintain thermal equilibrium, the rate at which Earth is emitting radiation to space must be the same at which it's receiving it. In this case, the rate is approximately 240 W/m^2 at Earth's surface.

If the ratio of incoming to outgoing energy changes, the temperature of the planet must also change to compensate for it. That's actually what's happening now; you and l know it as "global warming."

Note, though, that Earth actually receives much more energy than is absorbed by the surface. Only about 30% of total insolation (INcoming SOLar radiATION) reaches Earth's surface. Much is reflected off of clouds, aerosols, and ice. And some is absorbed directly into the atmosphere.

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Edit:

There isn't any lag. The gases reemit the energy almost immediately. A common misconception is that greenhouse gases "trap" energy in the atmosphere. What they're actually doing is slowing the rate at which energy is able to flow to space.

Think of it this way. Earth gets energy from the sun, which is reemitted as long wave radiation. In order to escape to space, this energy has to pass through the atmosphere. The greenhouse gases in the atmosphere absorb this energy, and reemit it again.

For this simple explanation, you can think of the atmosphere as radiating both up and down. Thus, when the greenhouse gases release their absorbed energy, half is radiated out to space, and half is radiated back toward the ground.

Since we know that the planet is absorbing 240 W/m^2 from the sun, and half of that amount from the atmosphere, it must now be receiving a total of 360 W/m^2. This progresses until Earth's surface is emitting a total of 480 W/m^2.

In order to radiate this much energy back to space, Earth's temperature has to go up. This is essentially how the greenhouse effect warms the planet's surface. Of course, real life is a lot more complicated than this simple radiative model, but this should give you a general idea. Check out chapter 2 of the IPCC AR4 for a much better explanation. Wikipedia also has an excellent explanation you might want to check out.

http://ipcc-wg1.ucar.edu/wg1/wg1-report.html

http://en.wikipedia.org/wiki/Greenhouse_effect

Answer 2

To travel away from the earth, heat has to travel outside the atmosphere; effectively through a vacuum. The only way heat can be transferred through a vacuum is via the electromagnetic spectrum (in the case of heat, via infrared radiation).
This means that any heat loss will be transferred away at the speed of light (about 300,000 km/second).

The other means of heat transfer (convection and conduction) are not possible through the near-vacuum outside the earth's atmosphere.

Answer 3

I wonder - Would that depend on the Specific Heat of the Earth?

Clearly a hot piece of metal doesn't cool down at the speed of light, even though it's giving off IR energy.

Answer 4

it would want to take you 10 years to get there relative to an intruder observer. in case you've been vacationing on the speed of sunshine you would possibly want to detect the completed go back and forth time as precisely 0, this is between the numerous causes you may not genuinely attempt this.

Answer 5

The speed of light. It's infrared radiation.

The big "slowdown" thing in global warming is the oceans. Deep ocean water is slow to warm.

Answer 6

same as it came to earth !