Defining Surface to Ambient Radiation To define a Surface to Ambient radiation: Do one of the following: In the Simulation study tree, right-click Thermal Loads and select Radiation . Click Simulation > Loads/Fixture > Radiation. In the Simulation toolbar, click Radiation . The Radiation PropertyManager appears. Under Type, click Surface to ambient. In the graphics area, select the faces. For models with beams or trusses, select Beams . To select all faces exposed to ambient radiation, click Select all exposed faces. To delete a face, right-click the face and select Delete. Ambient temperature is the environment temperature surrounding a model. Under Radiation parameters, do the following: Select the required unit and enter a value for the Ambient Temperature . To associate a time curve with the ambient temperature, click Use Time Curve , then click Edit, and import or define a time curve. The value of the ambient temperature at any time instant is calculated by multiplying the specified ambient temperature value by the corresponding Y value of the time curve. This option is available for transient thermal studies only. Set the Emissivity . To associate a temperature curve with the emissivity, click Use Temperature Curve , then click Edit, and import or define a temperature curve. The value of the emissivity at a given temperature is calculated by multiplying the specified emissivity value by the corresponding Y value of the temperature curve. Set the View Factor . Click . Parent topicRadiation Defining Surface to Surface Radiation Selecting All Exposed Faces Time Curve Radiation Emission from Real Surfaces Temperature Curve Radiation View Factors