Book contents
- Frontmatter
- Contents
- Introduction to first edition
- Introduction to second edition
- 1 Foundation of radiation theory
- 2 Radiative transfer
- 3 Interaction of radiation with matter
- 4 The emerging radiation field
- 5 Instruments to measure the radiation field
- 6 Measured radiation from planetary objects up to Neptune
- 7 Trans-Neptunian objects and asteroids
- 8 Retrieval of physical parameters from measurements
- 9 Interpretation of results
- Closing remarks
- Appendices
- References
- Abbreviations
- Index
9 - Interpretation of results
Published online by Cambridge University Press: 07 September 2009
- Frontmatter
- Contents
- Introduction to first edition
- Introduction to second edition
- 1 Foundation of radiation theory
- 2 Radiative transfer
- 3 Interaction of radiation with matter
- 4 The emerging radiation field
- 5 Instruments to measure the radiation field
- 6 Measured radiation from planetary objects up to Neptune
- 7 Trans-Neptunian objects and asteroids
- 8 Retrieval of physical parameters from measurements
- 9 Interpretation of results
- Closing remarks
- Appendices
- References
- Abbreviations
- Index
Summary
The preceding chapter demonstrates how the basic thermal, compositional, and cloud structures of planetary atmospheres can be inferred from infrared measurements. Some information on surface properties is also available. So far, however, there has been no discussion of how underlying physical processes cause these structures to develop and evolve. That is the purpose of this chapter.
We divide the discussion into four topics. In Section 9.1 we are concerned with the one-dimensional thermal equilibrium configuration of an atmosphere in the absence of internal motion. In Section 9.2 we expand the temperature field to three dimensions and investigate the dynamical properties of atmospheres. In Section 9.3 we address the question of how determinations of chemical composition imply the evolution of planets and the Solar System as a whole. Finally, in Section 9.4 we review measurements of the excess heat emitted by the planets, and discuss the importance of these measurements for determining the status of planetary evolution in the present epoch.
Radiative equilibrium
The absorption of solar radiation leads to heating within the atmosphere, while cooling is achieved by the emission of infrared radiation. Thermal gradients are established, and the magnitudes and directions of these gradients, coupled with the forces of gravity and planetary rotation, give rise to imbalances in local pressure fields that lead to atmospheric motions. These internal motions are responsible for additional energy transport, and it is the balance of the dynamical and radiative heating and cooling rates that determines the ultimate thermal structure of the atmosphere.
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- Chapter
- Information
- Exploration of the Solar System by Infrared Remote Sensing , pp. 405 - 464Publisher: Cambridge University PressPrint publication year: 2003