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發表於 2012-9-3 00:23:17
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資料分享 
A light pillar(光柱) is a visual(視覺的) phenomenon(現象) created(造成) by the reflection(反射) of light(光) from ice crystals(冰晶) with near horizontal(橫) parallel(並行) planar(平面) surfaces(表面). The light can come from the Sun(光可以來自太陽) (usually at(通常在) or low to the horizon(從低到地平線)) in which case the phenomenon(現象) is called a sun pillar(太陽光柱) or solar pillar(太陽光支柱). It can also come from the Moon(它也可以來自月球) or from terrestrial sources such as streetlights(從陸地來源，如路燈).
February 18, 2009--Oddly(奇怪) extraterrestrial(外星人)-looking, "broken(破碎)" light pillars(光柱) glow(發光) over Ath, Belgium, on November 20, 2006.
Refer above picture''Belgium, on November 20, 2006'' .Here the ice crystals(冰晶) have clumped(成群) into layers in an ice fog(在冰霧層) (see diagram)--rather than(而不是) spreading(傳播) out evenly(平等地)--according to physicist Les Cowley(根據物理學家萊斯考利) on his Web site Atmospheric Optics(大氣光學). As a result, light shining(閃亮) up from artificial sources(人工光源), such as streetlights(街燈), is turned into(變成) dotted(點線的) lines in the sky(天空).
Pillars
Look for sun pillars(尋找太陽的光柱) near to sunset(日落) or sunrise(日出).
They are narrow columns(狹小柱) of light apparently(表面上) beaming(聚束) directly up(直接上去) and sometimes downwards(向下) from the sun. They can be 5 -10º tall and occasionally(偶爾) even higher.
Pillars are not actually vertical rays(垂直陽光), they are instead the collective glints(集體閃閃發光) of millions of ice crystals(冰晶).
Pillars take on the colours of the sun and clouds(太陽和雲彩的顏色), they can appear(出現) white and at other times shades(色調) of yellow, red or purple.
Sometimes they appear(出現) as several vertically(垂直) strung(串) patches of light depending(根據) on the locations of the cloud(雲) crystals(晶體).
Ice Plates
Pillars often lengthen(加長) and brighten(變亮) after sunset(日落). Watch them creeping(爬行) northwards(向北) (southwards(向南) in the Southern Hemisphere(南半球), following the sun's movement(移動) below the horizon(地平線), for up to 30 to 60 minutes after it has set(集) at ground(地面) level.
Reflection of Light from Crystal Surface(從晶體表面的反射光)
Light pillars
Columns(柱) of light apparently(表面上) beaming(聚束) directly upwards(直接上去) from unshielded(非屏蔽) (and wastefully polluting) lights are sometimes visible(可見) during very cold weather(寒冷的天氣). Plate(碟) shaped(形) ice crystals(冰晶), normally only present in high clouds(通常只出現在高雲), float in the air close to the ground(漂浮在空中接近地面) and their horizontal(橫) facets(面) reflect light(反射光) back downwards(向下).
Pillar Formation from Low Sun
The pillars are not physically(物理) over(以外) the lights or anywhere(無論何處) else in space(空間) for that matter(事情) ~ like all halos they are purely the collected light beams(像所有的光環，它們是純粹收集到的光束) from all the millions of crystals(晶體) which just happen to be reflecting light towards your eyes or camera. (這恰好是對你的眼睛或相機的反射光。)
Artificial(人造的) light pillars can be much taller(遠高於) than their natural counterparts(自然同行) because rays(光) from the lights are not parallel(平行) and plate(碟) crystals(晶體) with small tilts(傾斜) can still reflect(反映) them downwards(向下). The crystals producing the pillars(晶體生產的柱) are roughly halfway(大約一半) between you and the lights.
Pillar Formation from Setting Sun
When ice crystals(冰晶) float(浮動) in the air(空氣) around you(在你周圍), pillars (and other halos(光環)) can even be seen(看到) around streetlights(路燈) a few metres away(數米之遙).
Light pillars(光柱) appear(呈現) when artificial(人造的) light (shown in diagram above) or natural light(自然光) bounces off(反彈) the facets(面) of flat(平) ice crystals(冰晶) wafting(信號) relatively(相對) close to the ground(靠近地面的).
When the light source is close to the ground(當光源是接近地面), the light pillar appears above the floating crystals(光柱會出現在浮動結晶上). When the light comes from the sun or moon(當光線來自太陽或月亮), the light pillar can appear beneath(在...下方) them, too, as the light refracts(折射) through(通過) the crystals.
Unlike(不像) the crystals(晶體) producing(產生) sun pillars(太陽光柱), those(那些) making tall artificial(人造的) light pillars(光柱) need not be strongly tilted(強烈傾斜). The column(柱子) producing pillars(柱) are approximately(大約) midway(半途) between the eye and the light source(光源). The higher(較高) the crystals(晶體) in the atmosphere(大氣層), the taller(高大) is the pillar(光柱). When the crystals are very high(當晶體是非常高) - or the light sources are close(或光源是接近) - the pillars(光柱) seem(似乎) to radiate(發光) from overhead(在上邊), the zenith(頂點).
Broad Pillar Formation from Street Light
Pillar Formation from Street Light
Summary
Ice crystals form in a wide variety of shapes and sizes(冰晶體形成各種各樣的形狀和大小): stars, needles(針), columns(柱) and plates(碟). When bright light passes from the sun, moon or an artificial light source(當明亮的光從太陽，月亮或通過人工光源部分) through a portion of the sky containing a concentration of ice crystals(通過局部的天空，含有冰晶的濃度), magical apparitions often appear(神奇的幻象往往會出現). The crystals focus(晶體焦點), scatter(分散), bend(彎曲), split(分裂) and reflect(反映) the light rays into a kaleidoscope(萬花筒) of optical phenomena(光現象): arcs(弧), glories(輝煌), halos(光環), pillars(柱) and sun dogs.
One particularly interesting form is the light pillar(一個特別有趣的形式是光的柱). They are most commonly seen as sun pillars; however, moonlight and strong artificial light such as street lamps can also form light pillars. (他們是最普遍被認為是太陽的光柱，但是，月光和強烈的人造光如路燈也可以形成光柱。)The pillar(柱) appears(出現) as a feather of light that extends vertically(垂直延伸) above and/or below the light source(光源).Most sun pillars(太陽光柱) are seen when the sun is low on the horizon(當太陽在地平線上) (generally no more than 6 degrees above) or just below(在...下面) it.
另一個可能原因是被稱為光柱（light pillar）的自然現象，此現象系由冰晶（ice crystal）反射光線所引起。然而，在目前炎熱的天氣下，空氣中可能沒有足夠的冰晶可以產生如此巨大而且清楚的光柱。
Sun and moon pillars are not restricted to the cold season since high altitude clouds can contain ice crystals.(太陽和月亮的光柱不限於寒冷的季節，因為高空雲層含有冰晶。) At times pillars(柱) occur simultaneously(同時發生) with other optical phenomena generated(其他光學現象的產生) by ice crystals(冰晶體) such as(比如) halos(光環) and sun dogs. However, blowing snow(風雪), ice fog(冰霧) and diamond dust(星塵) can not only produce(生產) interesting pillars(柱) with sun or moon light(太陽或月亮的光), but also generate(產生) very interesting effects(效果) around strong artificial light sources(強大的人工光源).
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