Earth’s Energy Budget

Abstract

Earth’s energy imbalance is the difference between the amount of solar energy absorbed by the Earth and the amount of energy it radiates to space as heat. If the imbalance is positive, more energy coming in than going out, we can expect Earth to become warmer. If the imbalance is negative, then more energy is going out than is being received and the Earth will cool. Earth’s energy imbalance is the single most crucial measure of the status of Earth’s climate and it defines expectations for future climate change. The Earth’s energy budget is explained in this chapter and the fact that Earth retains more of the electromagnetic radiation incident upon it from the Sun than it radiates back to space. The solar constant and aspects of solar electromagnetic radiation and the electromagnetic spectrum are discussed and illustrated. A distinction between weather and climate is made. Calculations of Earth’s temperature with and without an atmosphere are completed. Earth’s radiation laws are defined. The outgoing spectral radiance at the top of Earth’s atmosphere and the absorption at specific frequencies by greenhouse gases are illustrated.