Bibliography
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Halos from Prismatic Crystals
Atmospheric Halos and the Search for Angle x Item Type Book Authors Tape, Walter; Moilanen, Jarmo Publisher American Geophysical Union Download date 06/10/2021 22:55:50 Link to Item http://hdl.handle.net/11122/6400 CHAPTER 6 Halos From Prismatic Crystals his chapter treats what might be called the classical halos—the halos arising in Tthe simplest sorts of ice crystals, namely, hexagonal prismatic crystals. These halos, then, are not the odd radius halos. The treatment is not intended to be comprehensive. More information, including ray path diagrams and many more simulations, can be found in the book Atmospheric Halos [76]. Also, at the time of this writing there was at least one halo simulation program available on the internet.1 With it, you can change the sun elevation, the crystal shapes, crystal orientations, etc., and see for yourself how the halos are expected to change. The halos in this chapter are organized according to the crystal orientations that make them (Figure 6.1). By far the most common orientations are plate orientations, column orientations, and random orientations. Parry orientations are rare, and Lowitz orientations are rarer still. Plate arcs Recall that a crystal is in plate orientation when its two basal faces are (more or less) horizontal. Numbering the crystal faces 1, 2, . , 8 as in Figure 6.1, we always assume—without loss of generality—that in plate orientation it is face 1 that is the top horizontal face. The halos that arise in crystals with plate orientations are known as plate arcs. Plate arcs from prismatic crystals are shown in Figure 6.2. -
MSE3 Ch22 Atmospheric Optics
Chapter 22 Copyright © 2011, 2015 by Roland Stull. Meteorology for Scientists and Engineers, 3rd Ed. OptiCs COntents Light can be considered as photon particles or electromagnetic waves, ei- Ray Geometry 833 ther of which travel along paths called Reflection 833 22 rays. To first order, light rays are straight lines Refraction 834 within a uniform transparent medium such as air Huygens’ Principle 837 or water, but can reflect (bounce back) or refract Critical Angle 837 (bend) at an interface between two media. Gradual Liquid-Drop Optics 837 refraction (curved ray paths) can also occur within Primary Rainbow 839 a single medium containing a smooth variation of Secondary Rainbow 840 optical properties. Alexander’s Dark Band 841 Other Rainbow Phenomena 841 The beauty of nature and the utility of physics come together in the explanation of rainbows, halos, Ice Crystal Optics 842 and myriad other atmospheric optical phenomena. Parhelic Circle 844 Subsun 844 22° Halo 845 46° Halo 846 Halos Associated with Pyramid Crystals 847 ray GeOmetry Circumzenith & Circumhorizon Arcs 848 Sun Dogs (Parhelia) 850 Subsun Dogs (Subparhelia) 851 When a monochromatic (single color) light ray Tangent Arcs 851 reaches an interface between two media such as air Other Halos 853 and water, a portion of the incident light from the Scattering 856 air can be reflected back into the air, some can be re- Background 856 fracted as it enters the water (Fig. 22.1), and some can Rayleigh Scattering 857 be absorbed and changed into heat (not sketched). Geometric Scattering 857 Similar processes occur across an air-ice interface. -
Atmospheric Halos
Atmospheric Halos Rings around the sun and moon and related apparitions in the sky are caused by myriad crystals of ice. Precisely how they are formed is st11l a challenge to modern physics by David K. Lynch }tyone who spends a fair amount of halo and is bilaterally symmetrical with different length and is perpendicular to time outdoors and keeps an eye it. At the top and bottom the two are the plane of the a axes. on the sky is likely to see occa tangent. The circumzenith arc appears Although many forms of ice can oc sionally a misty ring or halo around the as an inverted rainbow centered on the cur. only about four are important in sun or the moon. The phenomenon is zenith. facing the sun. meteorological optics. The others are well established in folklore as a sign that Many other phenomena of this kind either too rare or do not have smooth. a storm is coming. Actually the halo is have been identified. and I shall describe regular optical faces. The important only one of a number of optical effects a number of them. As the optical effects forms are the plate. which resembles a that arise from the same cause. which is of atmospheric ice crystals are enumer hexagonal bathroom tile. the column. the reflection and refraction of light by ated. however. a point is reached where the capped column and the bullet (a col crystals of ice in the air. Whenever cir their existence and properties become umn with one pyramidal end). rus clouds or ice fogs form. -
Atmospheric Phenomena in Physics Teaching
Physics Competitions Vol 12 No 2 2010 Atmospheric Phenomena in Physics Teaching Ibolya Ságodi Dömény Garay János Grammar School Szekszárd, Hungary Abstract According to International researches, physics teaching has difficulties all over the world. The majority of students do not like physics. It is an important object to find those topics that stir enough the curiosity of the students. In our opinion, some interesting topics chosen from the field of atmospheric physics could be an appropriate tool of that. More precisely atmospheric optics would be perhaps one of the possibly best choices. The topic used by us is the phenomenon of halos, which has certainly been proved to be an interesting subject for high school teenagers. Several tens of individual halo forms are known because the various shapes and orientations of tiny hexagonal ice prisms allow light to take numerous different paths in an encounter with a crystal, ranging from simple refraction paths through a wedge to complex ray paths with several internal reflections. In this article the physics of halos and the results of a project made by Hungarian students will be shown. 1. Motivation The Earth’s atmosphere and processes occurring in it are very interesting and our everyday life is highly influenced by them. Clouds, thunderstorms, lightning and rainbows are beautiful, sometimes frightening and exciting phenomena. There are numerous people fanatically observing, taking photos and videos of them almost on daily basis. In spite of that, mainly due to the complexity of the processes mentioned above, curriculums deal with this field of physics only very modestly. However, it is not difficult to excite the curiosity of the students by these admirable spectacles.