Temperature correction frequency distribution. Shown are the dust emissivities, j_ν = κ_ν B_ν(T), prior to andafter the absorption of a single photon packet. The spectrum of the previously emitted packets is given by the emissivity at the old cell temperature (bottom curve). To correct the spectrum from the old temperature to the new temperature(upper curve), the photon packet should be re-emitted using the difference spectrum (shaded area). Image from Bjorkman & Wood (2001).