What happens to solar energy once it is absorbed by the Earth's surface?

• A. It heats the surface and is then re-radiated at a longer wavelength
• B. It heats the atmosphere directly
• C. It is reflected back into space untreated
• D. It is stored as chemical energy

Answer: (A)

Absorbed solar energy heats the surface and is then released as infrared radiation. When sunlight is absorbed by the ground, water, or vegetation, it raises the temperature of the surface. Any object at that temperature emits radiation, and for the Earth's surface this emission falls in the infrared, a longer wavelength than the incoming visible sunlight. So the energy taken in from the Sun is mainly converted to heat and re-emitted as infrared radiation. Some energy can go into processes like evaporation or, in plants, chemical storage via photosynthesis, but the immediate and general fate of absorbed solar energy at the surface is heat plus infrared emission.