The reader may be surprised to learn that the word "aeronomy" is not found in many of the standard dictionaries of the English language (for exam ple, Webster's International dictionary). Yet the term would appear to exist, as evidenced by the affiliations of the two authors of this volume (Institut d' Aeronomie Spatiale, Brussels, Belgium; Aeronomy Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA). Perhaps part of this obscurity arises because aeronomy is a relatively new and evolving field of endeavor, with a history dating back no farther than about 1940. The Chambers dictionary of science and technology provides the following defini tion: "aeronomy (Meteor. ). The branch of science dealing with the atmo sphere of the Earth and the other planets with reference to their chemi cal composition, physical properties, relative motion, and reactions to radiation from outer space" This seems to us an appropriate description, and it is reflected throughout the content of this volume. The study of the aeronomy of the middle atmosphere experienced rapid growth and development during the 1970's and 1980's, particularly due to con cern over the possibility of anthropogenic perturbations to the state of the middle atmosphere and its protective ozone layer. As a result, much has been learned regarding both the natural behavior of the atmosphere and the impact of man's activities upon it. In this book we shall attempt to describe the current state of the art as we see it.

Zusammenfassung
`... an important book at the right time. it is intended as an introduction to the field of middle atmosphere chemistry and physics and as a reference book for researchers in this area as well. There is no doubt that it can and will fulfil both tasks very well... Rich and solid material is presented for the evaluation of thermal and photochemical effects of radiation... outstanding and stimulating review... The authors themselves have made numerous important contributions to this development, a fact well reflected by the content and quality of their review.'
rBeiträge zur Physik der Atmosphäre, 58:1 (1985)
`... the material is up-to-date, presented in an illustrative manner, and is referenced extremely well.'
Pageoph, 1988
`*Aeronomy of the Middle Atmosphere is an interesting and well-written overview of the current status of our knowledge of the composition of the middle atmosphere and the basic radiative, dynamical and photochemical processes which maintain it. I am not aware of another book which addresses the middle atmosphere from such a broad interdisciplinary perspective ... Many atmospheric scientists will wish to add this book to their personal collections.*'Bulletin American Meteorological Society**

Inhalt

1. The Middle Atmosphere and Its Evolution.- 1.1 Introduction.- 1.2 Evolution of the Earth's atmosphere.- 1.3 Possible perturbations.- References.- 2. Chemical Concepts in the Atmosphere.- 2.1 Introduction.- 2.2 Thermodynamic considerations.- 2.3 Elementary chemical kinetics.- 2.3.1 Collision theory of bimolecular reactions.- 2.3.2 Unimolecular reactions.- 2.3.3 Termolecular reactions.- 2.4 Term symbols and their use.- 2.4.1 General.- 2.4.2 Selection rules for electronic radiative processes.- 2.5 Photolysis processes.- 2.6 Excited species in the middle atmosphere.- References and bibliography.- 3. Structure and Dynamics.- 3.1 Introduction.- 3.2 Vertical structure and some observed dynamical characteristics.- 3.3 Fundamental description of atmospheric dynamics.- 3.3.1 The primitive equations.- 3.3.2 The quasi-geostrophic potential vorticity equation.- 3.4 Effects of dynamics on chemical species.- 3.5 General circulation models.- 3.6 Dynamics of the stratosphere in two dimensions: a conceptual view.- 3.6.1 Zonal means and eddies.- 3.6.2 Descriptions of the mean meridional stratospheric circulation.- 3.7 The importance of wave transience and dissipation.- 3.8 One dimensional representations of the atmosphere.- References.- 4. Radiation.- 4.1 Introduction.- 4.2 Solar radiation at the top of the atmosphere.- 4.2.1 The sun as a black body.- 4.2.2 The observed solar spectrum.- 4.3 The attenuation of solar radiation in the atmosphere.- 4.3.1 Absorption.- 4.3.2 Scattering by molecules and aerosol particles.- 4.4 Radiative transfer.- 4.4.1 General equations.- 4.4.2 Solution of the equation of radiative transfer for wavelengths less than 4 µm: Multiple scattering.- 4.4.3 Solution of the radiative transfer equation at wavelengths longer than 4 µm: Absorption and emission of infrared radiation.- 4.5 The thermal effects of radiation.- 4.5.1 Heating due to absorption of radiation.- 4.5.2 Cooling by radiative emission.- 4.6 Photochemical effects of radiation.- 4.6.1 General.- 4.6.2 Absorption cross sections of the principal atmospheric molecules.- 4.6.3 Numerical calculation of photodissociation coefficients.- References.- 5. Composition and Chemistry.- 5.1 General.- 5.2 Oxygen compounds.- 5.2.1 Pure oxygen chemistry.- 5.2.2 The odd oxygen family and some observations.- 5.3 Carbon compounds.- 5.3.1 Methane.- 5.3.2 Methane oxidation chemistry.- 5.3.3 Some end products of methane oxidation: carbon monoxide and dioxide.- 5.4 Hydrogen compounds.- 5.4.1 General.- 5.4.2 Odd hydrogen chemistry.- 5.4.3 The odd hydrogen family and some observations.- 5.5 Nitrogen compounds.- 5.5.1 Sources of stratospheric nitrogen oxides.- 5.5.2 Chemistry of odd nitrogen and nitric acid in the stratosphere.- 5.5.3 The odd nitrogen family: lifetimes and observations.- 5.5.4 Chemistry of odd nitrogen in the lower thermosphere and mesosphere.- 5.5.5 The odd nitrogen family in the lower thermosphere and mesophere.- 5.6 Chlorine compounds.- 5.6.1 General.- 5.6.2 Chlorine chemistry.- 5.6.3 The odd chlorine family: lifetimes and observations.- 5.7 Other halogens.- 5.8 Sulfur compounds and formation of aerosols.- 5.9 Generalized ozone balance.- References.- 6. The Ions.- 6.1 Introduction.- 6.2 Formation of ions in the middle atmosphere.- 6.2.1 Effect of solar radiation.- 6.2.2 The effect of energetic particles.- 6.2.3 Comparison of different ionization processes.- 6.3 Positive ion chemistry.- 6.3.1 Positive ions in the E region.- 6.3.2 Positive ions in the D region.- 6.3.3 Positive ions in the stratosphere.- 6.4 Negative ion chemistry.- 6.4.1 Negative ions in the D region.- 6.4.2 Negative ions in the stratosphere.- 6.5 Effect of ionic processes on neutral constituents.- 6.6 Radio waves in the lower ionosphere.- References.- 7. Possible Perturbations and Atmospheric Responses.- 7.1 Introduction.- 7.2 The importance of coupling in the study of perturbations.- 7.3 The effect of changes in the solar irradiance.- 7.4 Particle precipitation.- 7.5 Volcanic emissions.- 7.6 Anthropogenic emissions.- 7.6.1 Carbon dioxide.- 7.6.2 Methane.- 7.6.3 Nitrous oxide.- 7.6.4 Aircraft in the troposphere and lower stratosphere.- 7.6.5 The chlorofluorocarbons (CFC's).- 7.6.6 Simultaneous perturbations 412.- References.- Appendix A. Numerical values of physical constants and other data.- Appendix B. Conversion factors.- Appendix C. Reaction rate constants.- Appendix D. Estimated mixing ratio profiles.