飛機雲：凡飛過必留下痕跡？ Contrails: More Than Just Streaks in the Sky
AUG. 14,2024 / Analytical Editors
Have you ever looked up into the sky on a clear day and seen an airplane flying high in the clouds? If so, you've probably also noticed the long white streaks it leaves behind in its path. They are called contrails, and there's more to these white lines in the sky than meets the eye.
The jet fuel that powers the engines of a plane is intensely hot, often burning at more than 500°C. In contrast, the air temperature at high altitudes where commercial flights typically cruise can reach as low as -56°C. When the hot exhaust gases, which include water vapor produced by the burning of fuel, encounter the frigid surrounding air, they cool rapidly. This rapid cooling causes the water vapor to condense into tiny water droplets or freeze into ice crystals, forming visible trails known as contrails.
你是否曾在晴朗的日子抬頭仰望天空，看到一架飛機在雲層中高高翱翔呢？如果有的話，你可能還曾注意到飛機在飛過的路徑上留下長長的白色條紋。這些條紋被稱為凝結尾，天空中的這些白色線條不像表面上所見的那麼簡單。
為飛機引擎提供動力的噴射機燃料非常熱，通常燃燒溫度超過攝氏五百度。相比之下，在商業航班通常進行平穩航行的高海拔處，氣溫可低至攝氏零下五十六度。當熱廢氣 ── 包含燃料燃燒產生的水蒸氣 ── 遇到周圍嚴寒的空氣時，會迅速冷卻。這種快速冷卻導致水蒸氣凝結成微小的水滴或凍結成冰晶，形成稱為凝結尾的可見軌跡。
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- leave behind... / leave... behind 留下...
- There's more to N than meets the eye. ...不如表面所見的那麼簡單。
- intensely adv. 極度地，強烈地
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