问答题 In practice, this is an advantage to the plane, which is already at a good height when it reaches the polar region and so does not need to climb, while at the same time cold air keeps the clouds down low.

【正确答案】

【答案解析】实际上，这一点有利于飞机飞行。当飞机到达北极上空时，它不需要再往上飞，因为冷空气使云层变得很低。