Historically, when the sun has been shining on the Arctic in the summer, 24 hours a day, most of the sunlight has been reflected by multiyear ice, which takes quite a while, many years to grow and become really bright.

从历史上看，当太阳在夏天一天 24 小时照射北极时，大部分阳光都被多年冰层反射了，而冰层需要相当长的时间，许多年才能变厚并变得真正明亮。