The Optical Aurora

1 The Occurrence and Cause of Auroras: a Short Introduction.- 1.1 Local Auroral Forms.- 1.2 Auroral Morphology.- 1.3 Particle Behaviour: Reflection, Absorption and Scattering.- References.- 2 The Electron Aurora: Main Characteristics and Luminosity.- 2.1 Introduction.- 2.2 N2+ Emission and Ionization.- 2.3 Theoretical Height Distribution of the First Negative N2+ Bands.- 2.4 Height Distribution of Other Emissions.- 2.5 Electron Energies Inferred from Height Distribution of Auroral Luminosity.- 2.6 Geometry and Motion of the Electron Aurora.- 2.7 Latitude Variations in Auroral Heights.- References.- 3 The Proton Aurora.- 3.1 Introduction.- 3.2 Theory of Hydrogen Line Emission.- 3.3 Observations on Hydrogen Lines.- References.- 4 The Optical Spectrum of Aurora.- 4.1 Description.- 4.2 Local Variations in the Spectrum.- 4.3 Latitudinal and Zonal Variations.- References.- 5 Physics of the Optical Emissions.- 5.1 Excitation.- 5.2 Deactivation.- 5.3 Interpretation of the Spectrum.- 5.4 The Lifetime of Metastable Oxygen Atoms.- 5.5 Helium Emissions.- 5.6 Sunlit Aurora.- Appendix (References to Data on Cross-Sections).- References.- 6 Temperature Determinations from Auroral Emissions.- 6.1 Introduction.- 6.2 Doppler Temperatures.- 6.3 Rotational Temperatures.- 6.4 Conclusions and Prospects.- References.- 7 Pulsing Aurora.- 7.1 Introduction.- 7.2 Pulsating Aurora.- 7.3 Flaming Aurora.- 7.4 Flickering Aurora.- 7.5 Streaming Aurora and Horizontal Waves.- 7.6 Correlation with Pulsations in the Magnetic Field and Telluric Currents.- 7.7 Correlation with Pulsations in X-Rays.- 7.8 Morphology of Pulsating Aurora.- References.- 8 Optical Aurora and Radio Observations.- 8.1 Introduction.- 8.2 Radio Absorption.- 8.3 E-Layer Ionization.- 8.4 Radio Auroras.- 8.5 VLF Radio Emissions and Radio Noise.- 8.6 Polar Cap Absorption (PCA) Events.- References.- 9 Auroral X-Rays.- 9.1 Production of X-Rays in Aurora.- 9.2 Observations.- References.