Question

Discuss the energy balance of the Earth as a whole: What form of energy does it primarily absorb?

What form of energy, if any, does it primarily emit? Does it emit substantially less than it absorbs?

Which has more entropy, the energy absorbed or the energy emitted?

Answer 1

Primarily Earth absorbs energy in the form of short wave radiation from the sun. When sun rays reach the Earth, some is reflected back to space by clouds, some is absorbed by the atmosphere, and some is absorbed at the Earth's surface. However, since the Earth is much cooler than the Sun, its radiating energy is much weaker (long wavelength) infrared energy. We can indirectly see this energy radiate into the atmosphere as heat, rising from a hot road, creating shimmers on hot sunny days. The earth-atmosphere energy balance is achieved as the energy received from the Sun balances the energy lost by the Earth back into space. In this way, the Earth maintains a stable average temperature and therefore a stable climate. Since change in entropy is directly proportional to the Heat absorbed, and energy absorbed is more than energy emitted so entropy in case of energy absorbed will be more.