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halo
- Definição1
- A ring or arc that encircles the sun or moon. Halos are caused by the refraction of light through the ice crystals in cirrus clouds.
- Fonte1
- SPELLMAN, Frank R. The Handbook of Meteorology. Lanham, Maryland: Scarecrow Press, Inc., 2013. 237 p. ISBN 978-0-8108-8613-1.
- Fonte2
- MAUNDER, Michael. Lights in the sky: identifying and understanding astronomical and meteorological phenomena. London: Springer, 2007. 233 p. (Patrick Moore’s Practical Astronomy Series). ISBN 978-1-84628-761-9.
- Fonte3
- GRÃ-BRETANHA. Meteorological Office. The meteorological glossary. 2nd ed. London: H. M. Stationery Office, 1930.
- Nota Adicional1
- The term halo, which might be applied to any circle of light round a luminous body, is restricted by meteorologists to a circle produced by refraction through ice crystals ; in contrast to coronae which are produced by diffraction. All the optical phenomena produced by reflection and refraction of light by ice crystals are sometimes grouped together as halo phenomena. The most common halo is a luminous ring of 22° radius surrounding the sun or moon, the space within the ring appearing less bright than that just outside. The ring, if faint, is white ; if more strongly developed the inner edge is a pure red, outside which yellow may be detected. The halo of 22° In England it can be seen by an assiduous observer is very common. about one day in three.
- Contexto
- Persistent sun dogs with what are often called “tails” pointing outward and associated with a quite definite halo are created by ice crystals usually associated with a weather front. That’s usually a nasty one lasting a day or two.
- Subárea
- Meteorology
- Français
- halo