按照常理来判断，你会觉得夏天一定是离太阳最近的时候。事实却正好相反。在每年1月初，地球运行到离太阳最近的位置，叫近日点。在7月初，地球离太阳最远，叫做远日点。既然1月初地球离太阳这么近，为什么我们却感受不到温暖呢？我们国家位于北半球。由于地轴倾斜的原因，在近日点的时候，太阳对北半球的日照时间短，因此北半球为冬季，南半球为夏季；在远日点的时候，北半球因日照时间长为夏季，南半球为冬季。走进下面文章，谜底即将揭开！
Leaning Toward Winter
Earth’s tilt causes the cold season
地轴倾斜与冬季的关联
By Ken Croswell, Ph.D. • Art by Josh Lewis
In December, Earth is more than a million miles closer to the Sun than usual. In early January, we’re the closest we ever get. That’s why the weather is so hot right now.
What’s that you say? The weather’s not hot? It’s freezing cold? With snow on the way? Hmm . . . There must be more to winter than our distance from the Sun.
Indeed there is. As Earth spins, it’s not straight up and down. Instead, it’s tilted. As Earth goes around the Sun, the North Pole always points the same way in space, toward a distant star called the North Star. This tilt of Earth causes the seasons.
During the half of the year we’re in now, the northern half of Earth points away from the Sun. That makes the weather cold for two reasons. First, the time from sunrise to sunset is shorter. So the northern half has fewer hours to soak up heat from the Sun. Second, the Sun doesn’t rise as high in the sky as it does in summer. As a result, winter sunlight is weaker, spread over more area. So even though Earth is closer to the Sun in winter than it is in summer, the planet’s tilt reduces sunlight enough to bring cold weather.
December 21 is the first day of winter. That’s when the northern half of Earth leans the most away from the Sun. But Earth’s northern half started leaning away from the Sun months ago. So wintry weather often arrives long before the official start of winter.
Don’t like the cold? Head to the southern half of the planet. Down there, summer starts on December 21 because that’s when the southern half of Earth leans the most toward the Sun.
HOW COLD IS YOUR WINTER?
1 COLDEST IN THE U.S.A.
Utqiagvik, Alaska
Average January Temperature: -8°F
Shortest Day (Amount of Daylight): 0 hours2 COLDEST, CONTINENTAL U.S.A.
International Falls, Minnesota
Average January Temperature: 0°F
Shortest Day: 8 hours, 17 minutes
3 WARMEST IN THE U.S.A.
Honolulu, Hawaii
Average January Temperature: 76°F
Shortest Day: 10 hours, 50 minutes
本文刊登在《英语沙龙》（原版阅读）
2022年12月刊
责任编辑：Zan
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