With significant advances in the field of atmospheric radiation and remote sensing in recent years, the need for an up-to-date treatment of radiation and cloud physics has become evident. This monograph addresses these advances, focusing on the physical principles and approximations required to develop specific subjects. In addition to its scientific value, the information presented here is essential for the development of better weather prediction models for medium- and long-range forecasting. It is also critical for achieving accurate retrieval of temperature and humidity profiles from satellite measurements, since new techniques for monitoring global biogeochemical changes rely on radiation theory and a precise knowledge of clouds and their role in radiative transfer.