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

Sunlight that comes in is largely in the visible spectrum of light.
The earth radiates heat out as light in the infrared spectrum.

Greenhouse gasses absorb a lot of infrared light, but little to no light in the visible spectrum, creating a one way mirror for heat. (methane for instance is completely transparent to our eyes, but is pitch black through an IR-camera)

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