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Atmospheric Halos and the Search for Angle x

Atmospheric Halos and the Search for Angle x

Walter Tape, Jarmo Moilanen

ISBN: 978-0-875-90727-7

Jan 2006, American Geophysical Union

238 pages

Select type: Hardcover

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Published by the American Geophysical Union as part of the Special Publications Series.

Atmospheric halos are visible phenomena of much beauty and fascination. From our earliest known records, dating from the Sumerian-Babylonian culture of 4-5,000 years ago, to modern researchers, halos have kept us looking skyward. Caused by light refracted through ice crystals floating in the atmosphere, they can appear at nearly any time and place. What do the ice crystals look like, especially those that make the exotic "odd radius" halos? What is the value of the elusive angle x, so critical to determining the shapes of these crystals? What halo displays do we understand well and what displays do we not understand at all?

This book responds to such questions, and more, with a multifaceted view of halo science. Experts and novices alike will find this book the definitive resource on the subject. Features include:

  • The "how to" in halo observation and photography
  • Carefully analyzed photos of rare halo displays and pyramidal ice crystals
  • The early history of halo science
  • Elegant new explanations of how halos form
  • Authoritative discussion of odd radius halos

We invite you to gaze up and discover the world of halos.

Preface vii

1 Introduction 1

2 Ice Crystal Gallery 9

3 The Beginnings of Halo Science 21

4 How Halos Form 33

5 Halo Simulations 43

6 Halos From Prismatic Crystals 51

7 Odd Radius Halos Are Real 65

8 Odd Radius Circular Halos 71

9 Some Crystallography 91

10 Pyramidal Ice Crystals 101

11 The Search For Angle x 113

12 Refraction Halos and Wedge Angle 129

13 The Spin Vector 133

14 A User's Guide To Halo Poles 137

15 Odd Radius Plate Arcs 145

16 Odd Radius Column Arcs 165

17 Odd Radius Parry Arcs 179

18 Other Wedge Angles? 183

Appendix A: Pattern for Crystal Model 195

Appendix B: Halo Terminology 197

Appendix C: Halo Observation and Photography 199

Appendix D: From Pixels to Degrees 203

Appendix E: More Crystallography 211

ppendix F: Living on the (w)Edge 219

Bibliography 227

Index 233