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Atmospheric Halos

Walter Tape (Editor)

ISBN: 978-1-118-66793-4 March 2013 American Geophysical Union 144 Pages


Published by the American Geophysical Union as part of the Antarctic Research Series, Volume 64.

Archdeacon Stuck was seeing halos formed in moonlight. Their daytime counterparts are surprisingly common, not only in the arctic but in temperate climates as well. Many halos are possible, forming arcs of colored or white light almost anywhere in the sky. Their occasional brilliance, variety, and exotic shapes have impressed skywatchers for centuries.

This book introduces halos and tries to convey some of their beauty. It tells much of what is known about them: how they arise, how so many are possible, and why some are rare, while others occur every few days or so. No such insights, of course, are necessary for the enjoyment of a halo display; indeed, an elaborate display is one of Nature's wonders. Nevertheless, understanding can add to enjoyment, especially since the makings of a great display turn out to be as remarkable as the display itself.


Chapter 1. Halos From Plate Crystals   1

Chapter 2. Halos From Column Crystals   13

Chapter 3. Halos From Parry Oriented Crystals   29

Chapter 4. The 220 and 460 Halos   45

Chapter 5. Why Are the Rare Halos Rare?   53

Chapter 6. The Role of Sun Elevation   58

Chapter 7. Subhorizon Halos   69

Chapter 8. Cold Weather Halos   77

Chapter 9. Organizing the Halos   78

Chapter 10. Pyramidal Crystals and Odd Radius Circular Halos   82

Chapter 11. Hevel's Halo and Other Mysteries   95

AppendixA . Suggestionfs or PhotographinHg Halos   105

Appendix B. Some History   106

Appendix C. Halo Simulations at Selected Sun Elevations   108

Appendix D. Ice Crystal Habit   122

Appendix E. Ray Paths for Halos   123

Appendix F. The Halo Simulation Program   132

Appendix G. Parameters of the Halo Simulations   134

Further Reading   138

References   138

Index   140