下面的照片是所謂的「火彩虹 (Fire Rainbow 的直譯 )」的照片；「火彩虹 」是發生在大
氣層中罕見的一種自然現象。
這張照片拍攝於美國愛達荷州與華盛頓州邊界處，照片上的「火彩虹」持續了1個小時
之久。
「火彩虹 」特殊現象產生的條件是：高空中捲雲層所在的高度至少要有 20,000英呎，
捲雲層裡有足夠的冰晶數量，另外就是太陽照射捲雲層的角度正好為58度。
氣層中罕見的一種自然現象。
這張照片拍攝於美國愛達荷州與華盛頓州邊界處，照片上的「火彩虹」持續了1個小時
之久。
「火彩虹 」特殊現象產生的條件是：高空中捲雲層所在的高度至少要有 20,000英呎，
捲雲層裡有足夠的冰晶數量，另外就是太陽照射捲雲層的角度正好為58度。
| Special Websites Recommended By Friends: Set 026 |
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| 火彩虹 Photo in the News: Rare "Rainbow" Spotted Over Idaho http://news.nationalgeographic.com/news/2006/06/060619-rainbow-fire.html received from 黃碧端 Pi-Twan Huang |
June 19, 2006—It looks like a rainbow that's been set on fire, but this phenomenon
is as cold as ice.
Known in the weather world as a circumhorizontal arc, this rare sight was caught on
film on June 3 as it hung over northern Idaho near the Washington State border
(map of Idaho).
is as cold as ice.
Known in the weather world as a circumhorizontal arc, this rare sight was caught on
film on June 3 as it hung over northern Idaho near the Washington State border
(map of Idaho).
The arc isn't a rainbow in the traditional sense—it is caused by light passing through wispy, high-altitude cirrus clouds. The sight occurs only when the sun is very high in
the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to
the ground.
When light enters through a vertical side face of such an ice crystal and leaves from the bottom face, it refracts, or bends, in the same way that light passes through a prism.
If a cirrus's crystals are aligned just right, the whole cloud lights up in a spectrum of colors.
This particular arc spanned several hundred square miles of sky and lasted for about an hour, according to the London Daily Mail.
—Victoria Gilman
the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to
the ground.
When light enters through a vertical side face of such an ice crystal and leaves from the bottom face, it refracts, or bends, in the same way that light passes through a prism.
If a cirrus's crystals are aligned just right, the whole cloud lights up in a spectrum of colors.
This particular arc spanned several hundred square miles of sky and lasted for about an hour, according to the London Daily Mail.
—Victoria Gilman
