The greenhouse effect
The Earth receives energy from the Sun in the form of radiation. To the extent that the Earth is in a steady state, the energy stored in the atmosphere and ocean does not change in time, so energy equal to the incident solar radiation must be radiated back to space.
Radiation leaving the Earth takes two forms: reflected solar radiation and emitted thermal infrared radiation. Earth radiates energy into space as black-body radiation, which maintains a thermal equilibrium. This thermal, infrared radiation increases withincreasing temperature. One can think of the Earth's temperature as being determined by the infrared flux needed to balance the absorbed solar flux.
