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
Yes, the sunlight warms the planet. As the planet rotates, the sunlight goes away. The warm atoms emit infrared light, actually all atoms can generate some light (what’s called black body radiation) but the greenhouse effect involves infrared.
Some of this infrared light makes it out of the atmosphere and into space, leaving the Earth forever. Some of this light is absorbed by gasses in the Earth’s atmosphere, warming those gas atoms. Those warmed gas atoms radiate some infrared light, half (approximately) going toward the Earth and half going away. Etc, etc, … .
The key to the greenhouse effect is the ratio between the light that “gets free of Earth” and the light that “goes back towards the Earth”. This ratio depends on the makeup of the gas in the atmosphere, because some molecules are much better at “catching” infrared light that others. The good catchers are called greenhouse gasses because they contribute the this rewarming effect.
Actually, this also happens on the sunny side of the Earth, but it’s not as easy to see as the night-time case.
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