Why is the greenhouse effect only one way?

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So what I’m reading is that these gas absorb the light from the sun and keeps it trapped on the earth.

What I don’t get is how is it letting the light and heat in from the sun in, but not the light and heat reflected from the Earth out? If it’s a barrier, shouldn’t it block both ways? If it’s not a barrier, how is it trapping the heat?

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Anonymous 0 Comments

A few things to note:

1. You know how you can’t see CO2? Like it’s completely invisible to you? This is because it’s very bad at absorbing visible light. It’s basically invisible to it for our purposes.
2. You know how when you wear a black shirt in the sun vs a white shirt, you get a LOT hotter. This is because you are absorbing a LOT more visible light which then warms you up.
3. When objects get warm, they emit heat either by warming the air/other stuff around them. They also emit light, but a much higher percentage of this light is emitted on the low end of the spectrum. It’s infrared light.
4. It turns out that infrared light can see CO2 quite readily and a lot of it is absorbed on the way back out of the planet.

Considering that the planet is always getting warmer from sun exposure, the only place for that heat to go is away in the form of light because you can’t conduct heat into a vacuum. So, anything that reduces the amount of light that radiates away from Earth will result in the planet retaining more heat.

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