This textbook is a first-look at radiative transfer in planetary atmospheres with a particular focus on the Earth's atmosphere and climate. It covers the basics of the radiative transfer of sunlight, treating absorption and scattering, and the transfer of the thermal infrared. The examples included show how the solutions of the radiative transfer equation are used to evaluate changes in the Earth?s energy budget due to changes in atmospheric composition, how these changes lead to climate change, and also how remote sensing can be used to probe the thermal structure and composition of planetary atmospheres. The examples motivate students by leading them to a better understanding of and appreciation for the computer-generated numerical results. Aimed at upper-division undergraduates and beginning graduate students in physics and atmospheric sciences, the book is designed to cover the essence of the material in a 10-week course, while the material in the optional sections will facilitate its use at the more leisurely pace and in-depth focus of a semester course.