This comprehensive text describes the atmospheric processes, numerical methods, and computational techniques required for a scientist to study successfully air pollution and meteorology. The book has been developed from the author's graduate courses at Stanford University and contains homework and computer programming assignments. The text includes several numerical techniques for simulating gas and aerosol processes not available in any other text. This will be a valuable textbook for graduate and upper-level undergraduate courses in atmospheric sciences and meteorology departments. It will also be useful for courses in earth sciences, environmental sciences, and applied mathematics.