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The Infrared Emissivity of an object is a measure of how efficiently the top layer of the object's atmosphere will emit infrared radiation. An object with an emissivity of one is a perfect blackbody and will absorb incoming radiation and re-emit it as thermal infrared radiation based on its temperature. Objects with lower emissivity values will emit infrared radiation at lower rates. An object with a single-layer atmosphere with an emissivity of zero will be perfectly reflective, absorbing and re-emitting none of the incoming energy as heat.

Property Details[]

Location[]

The Infrared Emissivity property is located at the end of the Atmosphere section of the Surface tab of an object's properties panel. This section is only visible for Terrestrial Planets.

Simulation Effects[]

Surface Temperature[]

The emissivity of the atmosphere, , affects the amount of heat energy that the atmosphere will radiate in all directions, including back down towards the surface of the object. The rate at which energy is added to the object's surface from this atmosphere heating, or the Atmosphere Power, is estimated as[1]

where is the Average Temperature of the object and is its Radius. The emissivity factor depends on the number of opaque layers that can represent the atmosphere, :[2]

If there is only one atmosphere layer, then

This atmosphere power contributes to the total Energy Absorption Rate of the object, which is used to calculate its Average Temperature.

  1. For example, see: American Chemical Society. A Single-Layer Atmosphere Model. ACS Climate Science Toolkit: How Atmospheric Warming Works.
  2. For example, see: American Chemical Society. A Multilayer Atmosphere Model. ACS Climate Science Toolkit: How Atmospheric Warming Works.
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