This book is intended for a semester undergraduate course in atmospheric thermodynamics. Writing it has been in my mind for a while. The main reason for wanting to write a book like this was that, simply, no such text in atmospheric thermodynamics exists. Do not get me wrong here. Excellent books treating the subject do exist and I have been positively influenced and guided by them in writing this one. However, in the past, atmospheric thermodynamics was either treated at graduate level or at undergraduate level in a partial way (using part of a general book in atmospheric physics) or too fully (thus making it difficult to fit it into a semester course). Starting from this point, my idea was to write a self-contained, short, but rigorous book that provides the basics in atmospheric thermodynamics and prepares undergraduates for the next level. Since atmospheric thermodynamics is established material, the originality of this book lies in its concise style and, I hope, in the effectiveness with which the material is presented. The first two chapters provide basic definitions and some useful mathematical and physical notes that we employ throughout the book. The next three chapters deal with more or less classical thermodynamical issues such as basic gas laws and the first and second laws of thermodynamics. In Chapter 6 we introduce the thermodynamics of water, and in Chapter 7 we discuss in detail the properties of moist air and its role in atmospheric processes. In Chapter 8 we discuss atmospheric stability, and in Chapter 9 we introduce thermodynamic diagrams as tools to visualize thermodynamic processes in the atmosphere and to forecast storm development.