天脈
The Veins of Heaven
來源：Clear Skies｜發表日期：2025-07-11
7 月 10 日，隨著天色逐漸變暗，太陽光也隨之變暗，瑞典斯德哥爾摩附近的瓦倫圖納湖平靜的水面上倒映著這一奇特的夜光雲。從距離地球表面約 80 公里的太空邊緣看去，儘管從地面上看太陽已在地平線以下，但冰雲本身仍然反射著陽光。夜光雲通常在夏季出現在高緯度地區，迄今為止，在北方短暫的夏夜，夜光雲已經大顯身手。據瞭解，夜照雲也被稱為極地中層雲，是由於水蒸氣進入寒冷的高層大氣，在流星或火山灰解體後產生的微塵顆粒上凝結而形成的。
原文：Transfusing sunlight as the sky grew darker, this exceptional display of noctilucent clouds was captured on July 10, reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds themselves still reflect sunlight, even though the Sun is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months, the night shining clouds have made a strong showing so far during the short northern summer nights. Also known as polar mesopheric clouds they are understood to form as water vapor driven into the cold upper atmosphere condenses on the fine dust particles supplied by disintegrating meteors or volcanic ash.
※ 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。