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
When a photon strikes a molecule there are basically two options:
* It is absorbed (and a lower energy photon is remitted shortly after)
* The photon passes through
Which of these happens depends on:
* The frequency/wavelength of the photon
* The specific electron configuration of the molecule
When the photon passes through the molecule we consider it to be transparent to that wave length of light. When it is absorbed and remitted, we say that it is opaque to that kind of light. But a substance that is transparent to one kind of light might be opaque to another. For example, glass is transparent to visible light but opaque to UV light.
So, most of the light from the sun is visible, which our atmosphere is mostly transparent to. It hits the earth and is absorbed and remitted as infrared light (which we feel as heat). Our atmosphere is opaque to infrared light, and does not allow it to pass back out into space, trapping the heat on the Earth.
That is the greenhouse effect.
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