By Walter Tape
Published through the yankee Geophysical Union as a part of the Special courses Series.
Atmospheric halos are noticeable phenomena of a lot attractiveness and fascination. From our earliest identified documents, courting from the Sumerian-Babylonian tradition of 4-5,000 years in the past, to fashionable researchers, halos have saved us taking a look skyward. brought on by mild refracted via ice crystals floating within the surroundings, they could look at approximately any time and position. What do the ice crystals seem like, specifically those who make the unique "odd radius" halos? what's the worth of the elusive perspective x, so severe to opting for the shapes of those crystals? What halo monitors will we comprehend good and what monitors will we no longer comprehend at all?
This booklet responds to such questions, and extra, with a multifaceted view of halo technology. specialists and newcomers alike will locate this e-book the definitive source at the topic. positive aspects include:
- The "how to" in halo statement and photography
- Carefully analyzed images of infrequent halo screens and pyramidal ice crystals
- The early heritage of halo science
- Elegant new motives of the way halos form
- Authoritative dialogue of wierd radius halos
We invite you to gaze up and notice the realm of halos.
Chapter 1 creation (pages 1–8):
Chapter 2 Ice Crystal Gallery (pages 9–20):
Chapter three The Beginnings of Halo technological know-how (pages 21–32):
Chapter four How Halos shape (pages 33–42):
Chapter five Halo Simulations (pages 43–50):
Chapter 6 Halos From Prismatic Crystals (pages 51–64):
Chapter 7 strange Radius Halos are actual (pages 65–70):
Chapter eight extraordinary Radius round Halos (pages 71–89):
Chapter nine a few Crystallography (pages 91–100):
Chapter 10 Pyramidal Ice Crystals (pages 101–112):
Chapter eleven the quest for attitude x (pages 113–128):
Chapter 12 Refraction Halos and Wedge attitude (pages 129–132):
Chapter thirteen The Spin Vector (pages 133–136):
Chapter 14 A User's consultant to Halo Poles (pages 137–144):
Chapter 15 ordinary Radius Plate Arcs (pages 145–164):
Chapter sixteen unusual Radius Column Arcs (pages 165–178):
Chapter 17 peculiar Radius Parry Arcs (pages 179–182):
Chapter 18 different Wedge Angles? (pages 183–194):
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Additional info for Atmospheric Halos and the Search for Angle X
T h e responsible crystals are oriented columns, and the ray paths are those that enter and exit alternate prism faces. T h e sun elevation is 20°. Wegener used stereographic projection from the zenith, w h i c h gives the halo a slightly unfamiliar look. T h e significance of the t w o red segments is explained on page 52. 2 C o m p u t e r s i m u l a t i o n s s h o w i n g halos f r o m oriented c o l u m n s . 1. (Left) Allowing only ray paths for the tangent arc, that is, ray paths that enter and exit alternate prism faces.
This ray path contributes to the circumzenith arc. 2. 1. W h a t would an observer see in t h e sky? T o answer such questions, you always need t o think about t h e way light rays from t h e sun pass through t h e crystals. 1. T h e r a y from t h e sun enters t h e upper basal face of t h e crystal and exits a prism face. T h e r a y is refracted downward as it enters t h e crystal and is refracted once more as it exits. T h e chance t h a t t h e outgoing ray from this particular crystal reaches t h e eye of our fixed observer is nil.
9]. F o r m a n y years the Memoire was quite literally t h e last word on halo theory, with virtually no important halo publications appearing again until t h e beginning of t h e t w e n t i e t h century. Today, a century a n d a half after its publication, t h e Memoire remains a classic reference. 8 (Opposite) OF HALO SCIENCE Evidence that halos are caused by ice crystals. In this low level halo display, discrete sparkles from nearby crystals are seen in the directions of the upper and lower tangent arcs.