Kamp, IngaIngaKampGALLI, DanieleDanieleGALLIRab, ChristianChristianRab2024-03-012024-03-0120249780323917469http://hdl.handle.net/20.500.12386/34853Each phase of the ISM has a temperature that results from a balance of heating and cooling. These processes differ from place to place in the Galaxy and vary with time. Under particular conditions, the resulting thermal equilibrium can be unstable and promote the separation of coexisting thermodynamic phases in pressure equilibrium with each other. Determining the temperature is a big challenge for numerical modeling as many different microphysical processes have to be considered and, usually, simplifying assumptions have to be made. This chapter discusses the most important known heating and cooling processes for various physical conditions (i.e., from the diffuse ISM to planet-forming disks). We provide the necessary equations and references to the required data but also discuss simplified methods and their assumptions for each process. We conclude with a brief description of how to solve the heating/cooling balance considering different levels of complexity.STAMPAenBook part10.1016/B978-0-32-391746-9.00019-5https://www.sciencedirect.com/science/article/abs/pii/B9780323917469000195?via%3Dihub2024asmo.book..283KFIS/05 - ASTRONOMIA E ASTROFISICA