Glossary term: 極圈

Description: 極圈是地球上兩條特定的緯線圈。位於北緯66°33′48.8″的極圈稱為北極圈，位於南緯66°33′48.8″的極圈稱為南極圈。由於地球自轉軸是傾斜的，北極圈以北和南極圈以南地區的冬季為“極夜”，夏季為“極晝”。極夜期間，太陽在地平線以下的時間超過24小時，暗夜可持續數月。極晝期間，太陽在地平線以上的時間超過24小時，白晝可持續數月。越靠近極點，則極晝和極夜最長。對於每個極地區域，極夜出現在冬至前後，極晝出現在夏至前後。

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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

This is an automated transliteration of the simplified Chinese translation of this term

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