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

The light from the sun that heats the earth up (visible light) is different from the light the earth emits to cool down (infrared light). GHGs are opaque to infrared light but not opaque to visible light. They slow down cooling but let the earth heat up at the same rate