Table of Contents

1 Introduction

1.1 Purpose and Scope

1.2 Observation and Photography Tips

     1.2.1 Where and when to look

     1.2.2 Photography tips

     1.2.3 Airplane-window optical effects

1.3 Organization of the Book

References

2 Sky Colors

2.1 Clear Sky Colors

2.2 Sunrise and Sunset Colors

2.3 Scattering by Smoke and Air Pollution

2.4 Skylight Angular Distribution

2.5 The Green Flash

2.6 Mie Scattering from Rain Drops and Cloud Droplets

References

3 Coronas and Iridescence

3.1 Corona

3.2 Iridescence

References

4 Rainbows and Cloudbows

4.1 Rainbow Colors and Geometry

4.2 Cloudbows and Fogbows

4.3 Rainbow and Cloudbow Polarization

4.4 Supernumerary Bows

4.5 Red and Infrared Rainbows

References

5 Glories

5.1 Glory Geometry

5.2 Glories and Airplane Shadow

5.3 Noncircular Glories

5.4 Opposition Effect and Heiligenschein

References

6 Shadows

6.1 Eclipses

6.2 Airplane Shadows

6.3 Mountain Shadows

6.4 Contrail Shadows

6.5 Cloud Shadows

6.6 Crepuscular and Anti-crepuscular Rays

6.7 Earth's Shadow

References

7 Water Colors and Glitter

7.1 Water Colors

7.2 Water Waves

7.3 Water Reflections

7.4 Glints and Glitter

References

8 Halos and Pillars

8.1 Refraction in Ice Crystals

     8.1.1 Sundogs or parhelia

     8.1.2 22-deg halo

     8.1.3 Upper and lower tangent arcs

8.2 Reflections from Ice Crystals

8.3 Other Ice Crystal Optical Effects

     8.3.1 Subparhelia

     8.3.2 Refraction in 90-deg prism ice crystals

     8.3.3 Bottlinger's rings

References

9 Noctilucent Clouds and Aurora

9.1 Midnight Sun

9.2 Noctilucent Clouds

9.3 Aurora

References

10 Colors from Polarization

10.1 Skylight Polarization

10.2 Colors from Birefringent Airplane Windows

References

11 Scenery and Interesting Sights

Appendix: International Airport Codes

Preface

This book is a result of curiosity about the optical world around us. I have always found the natural optical world interesting, and this interest was nurtured by my scientist father, who would take young me outside at night to see the rings of Saturn or to photograph the aurora, and who taught me by example through his constant experimenting. One way or the other, I had to be affected by growing up in a home where everyday life included the house getting cold because my father had turned off the furnace in the middle of the Alaskan winter night so that he could better measure the gravitational field of a grapefruit in his basement laboratory!

The lessons at home were followed by my own professional experiences of curiosity-driven learning. For example, as an undergraduate student at the University of Alaska I worked as an assistant for a Japanese film crew who made the world's first color video of the aurora. I spent hours being taught by the American engineer how a video camera works while the Japanese engineer taught me the Japanese vocabulary so I could serve as interpreter in a discussion of how the Japanese camera worked and how the Alaskan scientists could get one of their own. Growing up under the aurora was a special treat!

Later, when I was a Ph.D. student studying optical sciences at the University of Arizona, I remember being frustrated one evening when I realized I could not clearly explain the source of the beautiful colors I was seeing in a cloud while I waited at a bus stop near the university. I remember vowing right then to learn everything possible about natural optical phenomena so that I could understand and help others understand the optical beauty visible to all who learn to look and see. This vow led me to carefully study a book on this topic, written by Aden and Marjorie Meinel. Aden was the founding director of the Optical Sciences Center where I was a Ph.D. student, and I appreciate his kind response to my letter thanking him for his wonderful book. This was followed with books by Robert Greenler and Marcel Minnaert, and later with books by David Lynch and William Livingston, Syun Akasofu, and others. As my library and understanding grew, so did my collection of photographs. It was my love of photography that led me to study optics in the first place, so this was a natural evolution. Soon I was carrying a camera everywhere I went, meeting with the "light and color in the open air" community every few years, and traveling the world to share my photographs and their explanations with everyone from elementary school students looking in awe at my photographs of the aurora to graduate students and optics professionals who wanted to learn more about this inspiring field.

Because I travel the world for research and presentations, my collection grew to include more and more photographs taken from airplanes. I eventually realized this was a fitting niche for my own book, which I now offer with the hope that it might help inspire others to better see, appreciate, and understand the optical world.

This book would not exist without the contributions of many people and organizations. It is my sincere pleasure to acknowledge and thank my colleagues and friends in the "light and color in the open air" community for teaching, inspiring, and encouraging me: specifically, Michael Vollmer, Kathy Creath, and Stan Gedzelman for reading and helping improve chapters; Les Cowley for helping me identify and better understand some of the phenomena in my photographs; and Robert Greenler for graciously encouraging me in this project. The book is much better because of their help, but any flaws are still my own.

I offer my sincere thanks to Montana State University for allowing me to take a sabbatical leave, which gave me the crucial time to sort and edit photographs and write most of this book. I greatly appreciate Jed Hancock and the Space Dynamics Laboratory at Utah State University in Logan, Utah, and Kazuhiko Oka and Hokkaido University in Sapporo, Japan, for hosting my sabbatical stay; Paul Nugent for helping run my research lab during this time; and all of my students for being patient with me while I was away.

Among the many who have helped in some way, I also wish to thank the publishing team at SPIE for helping turn my idea into reality, Blake Lerner and Boeing Co. for providing information about the construction of airplane windows, and the following people who let me use their photographs to beautifully fill gaps in my own collection: Michael Vollmer, Paul Neiman, Daniel Adams, Glenn Shaw, Brad Hudson, Claudia Hinz, Brad Lee Hudson, and Dan McGlaun.

Finally, I gratefully acknowledge my parents, Glenn and Gladys Shaw, for teaching me to see the world scientifically but appreciate it spiritually and artistically; my wife, Margaret, for being by my side and giving it all meaning; and my children, Aaron, Brian, and Amy, for their constant encouragement and support. I cannot imagine completing this project without their love and help.

Joseph Shaw
December 2016