Heat is a branch of thermodynamics that occupies a unique position dueto its involvement in the field of practice. Being linked to themanagement, transport and exchange of energy in thermal form, itimpacts all aspects of human life and activity.Heat transfers are, by nature, classified as conduction, convection (whichinserts conduction into fluid mechanics) and radiation. The importanceof these three transfer methods has resulted justifiably in a separatevolume being afforded to each of them. This second volume is dedicatedto radiation. After recalling photometry, the calculation of luminance isaddressed using the theory of the black body and associated laws: Stefan,Wien. The reciprocal radiation of two surfaces in total influence isdiscussed extensively, and the case of finished surfaces is alsoconsidered.Heat Transfer 2 combines a basic approach with a deeper understandingof the discipline and will therefore appeal to a wide audience, fromtechnician to engineer, from doctoral student to teacher-researcher.