Contrail Shadow X
Contrail Shadow X
來源：Fatih Ekmen｜發表日期：2024-04-23
是什麼在雲層中形成了這個巨大的 "X"？那是從下面照亮的飛行軌跡的陰影。飛機飛行時，潮溼的發動機廢氣可能會形成水滴，這些水滴可能會在地球寒冷的高層大氣中結冰。 這些持續不斷的水流和冰流會散射來自上方太陽的光線，因此從下方看會很亮。不過，在極少數情況下，當太陽接近地平線時，會從下方照到忌霧。 這些忌霧向上投下長長的影子，除非雲層很高，否則這些影子通常是看不見的。本月初，土耳其伊斯坦布林上空就出現了這種情況。一般來說，當煙塵捕捉紅外線時會使地球變暖，而當它們有效地反射太陽光時則會使地球降溫。這張圖片是一位攝影師在早晨上班途中驚訝地拍攝到的。
原文：What created this giant X in the clouds? It was the shadow of contrails illuminated from below. When airplanes fly, humid engine exhaust may form water droplets that might freeze in Earth's cold upper atmosphere. These persistent streams of water and ice scatter light from the Sun above and so appear bright from below. On rare occasions, though, when the Sun is near the horizon, contrails can be lit from below. These contrails cast long shadows upwards, shadows that usually go unseen unless there is a high cloud deck. But that was just the case over Istanbul, Türkiye, earlier this month. Contrails occur all over planet Earth and, generally, warm the Earth when the trap infrared light but cool the Earth when they efficiently reflect sunlight. The image was taken by a surprised photographer in the morning on the way to work.
※ 本文由萌芽機器人自動轉貼自每日一天文圖（Astronomy Picture of the Day，APOD），原文為英文，正體中文是透過 DeepL 翻譯及 OpenCC 進行自動處理，內容僅供參考，若有任何錯誤之處還請見諒！
關於每日一天文圖：每日一天文圖網站是美國國家航空暨太空總署與密西根理工大學提供的服務，網站每天提供一張影像或圖片，並由天文學家撰寫扼要說明其特別之處。