Radiation that is emitted or reflected back in response to incident radiation, or radiation that opposes the effect of other radiation.
From counter- + radiation, from Latin radiare (to shine). The term combines the prefix with the scientific term for energy emission.
Counterradiation is why the greenhouse effect works—Earth's surface radiates heat back upward, but greenhouse gases re-radiate that heat back down, creating a warming effect that's trapped in our atmosphere.
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