Balance and Change

For Earth’s surface temperatures to remain steady, heat gain from sunlight must equal heat loss to the atmosphere. Energy equilibrium occurs when incoming energy equals outgoing energy.

Incoming Sunlight

Outgoing Heat

Borrowing the concept of an accountant's ledger with accounts payable and account receivable, the balance of incoming and outgoing energy is the atmosphere's energy budget.

Because of Earth's orientation to the sun, solar radiation is directed at the equator more so than to the poles. Evaporation, convection, rainfall, winds, and circulation are all processes working non-stop in the atmosphere and in the oceans to redistribute energy from incoming solar radiation.

Any phenomena that disturb the balance of incoming or outgoing energy (i.e., atmospheric energy budget) changes Earth’s net energy. Surface temperatures rise or fall accordingly.

In a state of energy equilibrium, mean temperatures would not change.

“It ever was, and is, and shall be, ever-living fire, in measures being kindled and in measures going out.”
― Heraclitus, (535-475 BC)

REFERENCES

• Climate and Earth's Energy Budget, Rebecca Lindsey, Earth Observatory, 2009.
• Diagram of the Earth's Energy Budget, Wikipedia.
• Earth’s Energy Budget, Earth Observatory.