Why is the greenhouse effect only one way?

Question

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?

In: 950

Answer 1

Sunrays heat the earth, which then radiates heat out, and due to the greenhouse gasses can’t get out. It’s very symilar to how actual greenhouses work (hence the name) or most forms of insulation, by trapping heat.