I have a plethora of questions regarding thermodynamics and all of them came to my mind while I was thinking about how the greenhouse effect actually works. (hence the title)
The sun emits radiation, which after 8 minutes hits the surfaces on planet earth. Here this radiation is reflected OR absorbed and turned into thermal energy.
Now from my understanding, thermal energy is kinetic energy on the particle level. For this form of energy to be transferred or absorbed, the particles would have to hit less energetic particles and thus energize them, which then would make them “warm” right?
Assuming that my explanation is mostly correct, why does space around us not heat up? By that logic, the particles in an imperfect vacuum would have to be highly energetic because of constant unshielded exposure to the light of millions of stars.
Would that also mean that sunlight consists of extremely fast particles that energize surfaces when they hit them? (If not, how does sunlight energize particles.
Why exactly does the thermal energy not just escape into space? Earth seems to be more energetic than space around us. Normally two asymmetric thermodynamic systems would balance out.
Sorry if I’m way off. I’m merely an ignorant student.
In: Physics
You’ve asked a few different questions all wrapped up in one here. Let’s go step by step.
First off, energized particles smacking into other energized particles is not the only way energy transfer can occur. You may have heard that heat can transfer 3 ways: conduction, convection, and radiation. Both conduction and convection requires particles to smack into each other. Radiative heat transfer does not. Particles can absorb electromagnetic radiation (just a fancy word for light) to gain energy, and particles can lose energy by emitting electromagnetic radiation.
> Would that also mean that sunlight consists of extremely fast particles that energize surfaces when they hit them?
So as explained above, no. Sunlight is electromagnetic radiation. It is absorbed by particles which causes them to heat up.
> Assuming that my explanation is mostly correct, why does space around us not heat up?
There’s nothing in space to heat up. Space is empty (well mostly, but for the sake of heat transfer, it’s empty). There is no conductive or convective heat transfer between Earth and space. Only radiative heat transfer. Energy is absorbed by the earth from the sun, and is radiated back out into space as infrared. The system is more or less an equilibrium.
Climate change occurs when increasing amounts of greenhouse gases decrease the amount of infrared radiation emitted by the earth that escapes into space.
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