What is the Earth’s Radiation Budget?

The Earth’s Radiation Budget is a concept used for understanding how much energy the Earth gets from the Sun and how much energy the Earth-system radiates back to outer space.

If the Earth system (Earth surface, atmosphere, oceans and ice mass) retains more solar energy than it radiates back to space, the Earth will warm. If the Earth-system radiates more energy to space than it receives from the Sun, the Earth will cool.

Scientists think of the Radiation Budget in terms of a see-saw or balance. If the Earth retains more energy from the Sun, the Earth warms and emits more infrared energy. This brings the Earth’s Radiation Budget into balance. If the Earth emits more of this energy than it absorbs, the Earth cools. As it cools, the Earth emits less energy. This change also brings the Radiation Budget back into balance.

Absorbed sunlight raises the Earth’s temperature. Emitted radiation or heat lowers the temperature. When absorbed sunlight and emitted heat balance each other, the Earth’s temperature doesn’t change – the radiation budget is in balance.

Earth balanced by the Sun on a see-saw.

Basic Parts of the Radiation Budget

  • Solar Incident Energy
  • Solar Reflected Energy
  • Earth Emitted Energy
Incoming solar radiation is absorbed by the Earth’s surface, water vapor, gases, and aerosols in the atmosphere. This incoming solar radiation is also reflected by the Earth’s surface, by clouds, and by the atmosphere. Energy that is absorbed is emitted by the Earth-atmosphere system as longwave radiation. The component diagram has additional details.
Light from the sun is absorbed and reflected by the earth.