| 词条 | Anticrepuscular rays |
| 释义 |
Anticrepuscular rays are most frequently visible around sunrise or sunset. This is because the atmospheric light scattering that makes them visible is larger for low angles to the horizon, backscattering, (see Mie theory) than at most other angles. Anticrepuscular rays are dimmer than crepuscular rays because backscattering is less than forward scattering. Anticrepuscular rays can be continuous with crepuscular rays, curving across the whole sky in great circles.[4] Mountain shadowA common example of a single anticrepuscular ray is provided by the shadow of a mountain at sunset, when viewed from the summit. It appears to be triangular, whatever the shape of the mountain, with the apex at the antisolar point.[4] Wagon-wheel spokesAnticrepuscular rays are sometimes seen enclosed by a rainbow (see picture). In this case they can be called wagon-wheel spokes.[4] References1. ^{{cite web|url = http://www.atoptics.co.uk/atoptics/anti1.htm|title = Anti-solar (anti-crepuscular) rays|first = Les|last = Cowley|work = Atmospheric Optics|accessdate = March 19, 2015|mode = cs2}} 2. ^{{cite book|pages=124–127|url=https://books.google.com/books?id=0cpQGHqxQBUC&pg=PA124|author=John A. Day|title=The Book of Clouds|year=2005|publisher=Sterling Publishing Company, Inc.|isbn=978-1-4027-2813-6|mode = cs2}} 3. ^{{cite web|url = http://atoptics.co.uk/fz1113.htm|title = Antisolar rays|first = Les|last = Cowley|work = Atmospheric Optics|accessdate = March 19, 2015|mode = cs2}} 4. ^1 2 Lynch, D. K., & Livingston, W. (1995). Color and light in nature. Cambridge: Cambridge University Press. External links
1 : Atmospheric optical phenomena |
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