If Type is set to Convection, then the dialog will look as shown below.
Convection loads can only be applied in heat transfer analyses. When attempting to add a convection load to a structural analysis, a warning will be issued. Convection can be applied to curves and surfaces.
The ambient temperature can be time dependent when the analysis type is set to nonlinear transient heat transfer. The convection coefficient can only be temperature dependent if the analysis type is set to nonlinear steady state heat transfer.
Convection loads can have custom display properties such as color, size, and density.