Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 An overview
- 2 The interaction of energetic solar photons with the upper atmosphere
- 3 The interaction of energetic electrons and ions with the upper atmosphere
- 4 Collisions and reactions
- 5 Ion and neutral composition of the upper atmosphere
- 6 Temperatures in the upper atmosphere
- 7 Spectroscopic emissions
- 8 Dynamics of the thermosphere and ionosphere
- Appendices
- Index
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 1 An overview
- 2 The interaction of energetic solar photons with the upper atmosphere
- 3 The interaction of energetic electrons and ions with the upper atmosphere
- 4 Collisions and reactions
- 5 Ion and neutral composition of the upper atmosphere
- 6 Temperatures in the upper atmosphere
- 7 Spectroscopic emissions
- 8 Dynamics of the thermosphere and ionosphere
- Appendices
- Index
Summary
Introduction
The definition of the term ‘upper atmosphere’ is not agreed upon by all scientists. To meteorologists it usually refers to the entire region above the troposphere, where the daily weather evolves. With this interpretation the upper atmosphere would include the stratosphere, mesosphere, and thermosphere, regions identified by their temperature structure, density, composition and the degree of ionization. Figure 1.1.1 illustrates schematically the altitude variation of these atmospheric parameters. Logarithmic scales are used for the abscissae and the ordinate to accommodate the large range of densities and heights.
The same laws of physics apply throughout the atmosphere, of course, but the relative importance of various processes varies widely between regions, accounting for the different behaviour of the characteristic parameters as a function of altitude. Thus, the temperature structure is governed by the absorption of solar radiation, and different wavelength bands are absorbed by various constituents in the region. For example, absorption by O3 specifically accounts for heating in the stratosphere. Radiation transfer and terrestrial albedo also contribute to the temperature structure. Each region identified in Figure 1.1.1 warrants a book length treatment. In this work we study that portion of the upper atmosphere labelled the thermosphere and ionosphere.
For centuries, man's perception of the thermosphere was limited to the splendour of the Aurorae Borealis and Australis. It was the need for the propagation of radio waves over long distances that provided a practical stimulus to investigations of the thermosphere and the physical processes that cause and control the ionosphere.
- Type
- Chapter
- Information
- Physics and Chemistry of the Upper Atmosphere , pp. 1 - 7Publisher: Cambridge University PressPrint publication year: 1989
- 1
- Cited by