Lesson 11: Energy Budget

The Earth's Radiation Energy Balance

An object will warm or cool depending on its energy imbalances. If the object receives more energy than it losses, the object will warm. If the object losses more energy than it receives it will cool, and if the energy gains equal the energy losses, there is no temperature change. Methods of transferring energy in the atmosphere include conduction, convection, latent heating, advection and radiation. The method of transferring energy through radiative processes is different from the other mechanisms in that the transfer process does not require molecules.

If we consider the planet as a whole, the Earth exchanges energy with its environment (the solar system) via radiation. The radiation balance of the planet is a fundamental parameter that determines our climate. This balance includes energy from the sun, or solar energy, which is an energy source for the planet. Any object that has a temperature emits radiation. The hotter the object, the greater the amount of energy emitted. Energy emitted by terrestrial objects is referred to as terrestrial, infrared, or longwave radiative energy.

The determination of the Earth's radiation budget is essential to atmospheric modeling and climate studies. Radiation budget experiments have used satellites to measure the fundamental radiation parameters:

1. the amount of solar energy received by the planet, (Solar incoming applet)
2. the planetary albedo (the portion of incoming solar radiation that is reflected back to space), (ERBE ALBEDO)
3. the emitted terrestrial radiation (also referred to as the outgoing longwave radiation -- OLR), and (ERBE OLR)
4. the net planetary energy balance (the difference between the absorbed solar energy and the OLR). (ERBE NET)

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