北回归线

例句：

1. 1. The sun sets over the South Pole, marking the end of summer in the Northern Hemisphere.
   太阳在南极落下，标志着北半球夏季的结束。
2. 2. During the winter months, the North Polar Region experiences long periods of darkness.
   冬季，北极地区长时间处于黑暗中。
3. 3. The Arctic Circle is a line that demarcates the latitude where the Sun's rays reach their northernmostextent.
   北极圈是一条界限线，界定了太阳光线到达最北端的纬度。