TeXes Science Practice Test

What type of electromagnetic radiation reaches the Earth and is emitted back into space as heat energy?

1. Ultraviolet

2. Microwaves

3. Visible light

4. Infrared

The correct answer is: Infrared

The type of electromagnetic radiation that reaches the Earth and is emitted back into space as heat energy is infrared radiation. When the Sun's energy reaches the Earth, it is primarily in the form of visible light, which is absorbed by the Earth’s surface. This energy is then re-radiated in the form of infrared radiation, which is associated with heat. Infrared radiation has longer wavelengths than visible light and is not visible to the human eye, but it plays a crucial role in the Earth's energy balance. The Planet absorbs solar energy during the day and releases it at night as infrared radiation, which contributes to the earth's temperature regulation. In contrast, ultraviolet radiation is mostly absorbed by the ozone layer and does not reach the Earth's surface in significant amounts, while microwaves are generally used for communication and do not play a substantial role in the Earth's radiative properties. Visible light, while influential in warming the planet, does not provide the primary mechanism for re-radiation of heat energy back into space. Thus, infrared effectively captures this process of energy absorption and re-emission.