This companion provides a collection of frequently needed numerical data as a convenient desk-top or pocket reference for atmospheric scientists as well as a concise source of information for others interested in this matter. The material contained in this book was extracted from the recent and the past scientific literature; it covers essentially all aspects of atmospheric chemistry. The data are presented primarily in the form of annotated tables while any explanatory text is kept to a minimum. In this condensed form of presentation, the volume may serve also as a supplement to many textbooks used in teaching the subject at various universities.