(相关资料图)
因为昼夜长短的变化是由于地球倾斜自转，同时绕太阳做公转运动造成的。从夏至后，太阳对地球的直射点逐日南移；秋分后太阳直射点移到赤道以南，分布到北半球的阳光逐日减少，因此北半球到冬天白昼时间就逐日缩短，而黑夜却逐步加长。
(相关资料图)
因为昼夜长短的变化是由于地球倾斜自转，同时绕太阳做公转运动造成的。从夏至后，太阳对地球的直射点逐日南移；秋分后太阳直射点移到赤道以南，分布到北半球的阳光逐日减少，因此北半球到冬天白昼时间就逐日缩短，而黑夜却逐步加长。
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