When they re-enter the troposphere, they are rapidly washed out of the atmosphere by rain and snow.

当重新回到对流层时，它们将很快被大气中形成的雨雪所洗刷殆尽。

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Above the troposphere, seen as a light blue band with white clouds, is the stratosphere, part of the Earth's atmosphere where airplanes fly and some hardy bacteria float.

对流层上面，淡蓝色有白色云的是平流层，飞机飞行所在的地球大气层，某些顽强的菌类在这里漂浮。

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Troposphere — the atmosphere which is closet to the earth. Its depth ranges from about 10 miles over the equator to about 5miles over the poles.

对流层——接近地表的大气层。它的距赤道深度超过10英里距两极超过5英里。

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Ozone in the lower atmosphere (troposphere) is regarded as a serious pollutant that can cause respiratory problems, and even damage masonry and agricultural crops.

BBC: London's clue to stubborn ozone levels

For instance, clouds rising in the troposphere, the lower level of the atmosphere where air mixes freely, will bump up against the boundary of the much more stable stratosphere, forming ripples in the process.

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