For the atmospheric layer between 30 and 170 km, the radiative heat influx in vibrational CO₂ bands is refined. The refinement is based on (1) the most comprehensive model currently available for the system of vibrational states and corresponding optical transitions, (2) updated data on the rates of vibration-translation and vibration-vibration processes, and (3) a computational procedure providing a high accuracy of the results. For the rate of nighttime radiative cooling, two trends are revealed. (a) A significant increase in the rate of lower-thermosphere cooling is possible in the 15-μm band under consideration. This increase is due to collisions between CO₂ molecules and O atoms, which are accompanied by multiquantum ν₂-mode transitions. (b) The contribution of cooling in the 4.3-μm CO₂ band reaches 0.2-0.35°C/day at the stratopause. For daytime conditions, the contribution of each individual CO₂ band between 15 and 1.05 μm to the integral radiative heating in CO₂ bands and the dependence of this heating on the solar zenith angle are studied. The parametrization of the rate of nighttime atmospheric radiative cooling in the 15-μm CO₂ band is improved.