All things with a temperature above
absolute zero emit radiation. Everything, your body, your desk, your house, grass, snow, the atmosphere, the moon, they all emit a wide range of radiation. The source of this electromagnetic radiation are vibrating electrons that exist in every atom that makes an object.
Emitted radiation can be:
- Absorbed
Increasing the internal energy of the gas molecules.
- Reflected
Radiation is not absorbed or emitted from an object but it reaches the object and is sent backward. The Albedo represents the reflectivity of an object and describes the percentage of light that is went back.
- Scattered
Scattered light is deflected in all directions, forward, backward, sideways. It is also called diffused light.
- Transmitted
Radiation not absorbed, reflected, or scattered by a gas, the radiation passes through the gas unchanged.
The temperature of an object can tell us something about the emitted radiation.
- The Stefan-Boltzmann law tells us that as the temperature of an object increases, more radiation is emitted each second.
E = σT4
where σ is a constant, T is the temperature of an object in Kelvin and E is the maximum rate of radiation emitted per meter2.
- Wien's law describes the maximum wavelength that an object emits based on it's temperature.
- where λmax is the wavelength in micrometers (μm) at which the maximum radiation emission occurs, θ is a constant equal to 2897 μm K, and T is the temperature in Kelvin.