Greenhouse Effect
The thermodynamic warming process by which atmospheric greenhouse gases absorb outgoing infrared terrestrial radiation and re-emit it in all directions, raising surface temperatures.
Governing formula
T_surface = T_effective (1 + ¾ τ_IR)^(1/4) (Radiative Equilibrium)
SI unit
°C or Kelvin (Warming Effect)
In depth
Earth's surface absorbs solar visible light and re-radiates it as thermal infrared light (~10 μm). Greenhouse gases (H₂O, CO₂, CH₄, N₂O) absorb outgoing IR radiation and re-radiate thermal heat back down, raising Earth's mean temperature from -18 °C to +15 °C.
Examples in the real world
Carbon dioxide and water vapor maintaining Earth's temperate climate, and runaway greenhouse effect on Venus.