Final answer:
In the surface energy budget, the term - SW reflects outgoing shortwave radiation, which includes the portion of solar energy reflected back into space from the Earth. This is distinct from the longwave radiation that the Earth emits as it re-radiates absorbed energy back into space.
Step-by-step explanation:
In the context of the surface energy budget, the term - SW typically represents the outgoing shortwave radiation. This radiation consists of the solar energy that has been reflected back into space from the Earth's surface or atmosphere. Shortwave radiation includes all forms of solar radiation, which span from ultraviolet rays, through visible light, to the shorter wavelengths of infrared. However, the energy that is not reflected and instead absorbed by the Earth is what drives crucial processes such as evaporation of water, the hydrological cycle, winds, and photosynthesis.
The absorbed solar radiation also contributes to outgoing longwave radiation, as the Earth re-radiates energy back into space in the form of heat, mostly in the infrared spectrum. This radiation can be described through the Stefan-Boltzmann law, which states that a body emits radiation in relation to its temperature and surface area. In the surface energy budget, the balance between the incoming shortwave radiation from the sun and the outgoing longwave radiation from the Earth is crucial in maintaining the Earth's energy equilibrium and thus its temperature.