This meteorology manual is first intended for aeronautical users. As it is an initiation for many students, it is not weighed down with in-depth theoretical developments, or with meaningless equations. It is really intended to help you understand the essentials, the most basic atmospheric principles and mechanisms. You will see that it is not too simplistic or popular. The atmosphere is complex and you will perhaps discover this. It goes without saying that this book includes all the knowledge required for the FCL European programme in its most complete version, the Air Transport Pilot Licence. The language and symbols used, as the illustrations, are essentially aeronautical. Additional information (yellow boxes) or anecdotes (blue boxes) are added to the subject. This manual is not intended to bore you, but to give you good knowledge of meteorology and help to improve safety and efficiency in aviation.» This manual has been written by Mr H. Hallot, Mr D. Labyt and Mr JH. Robres, teachers in the French national university for meteorology (ENM) and in the French national university for aviation (ENAC).