If a stratum of air saturated with moisture meets a very cold one, the fog begins to freeze, and becomes specks of snow.

如果含水量达到饱和状态的空气遇到了非常冷的另一团空气，空气中的原先呈雾状的水分就开始凝结变成小的雪粒。

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Within about a millimeter of the water, air temperature is close to that of the surface water, and the air is nearly saturated with water vapor.

在离水不到一毫米的地方，空气的温度接近于地表水的温度，空气中的水蒸气几乎饱和了。

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For each degree Celsius of warming, 7% more water is available to rain down from saturated air masses.

气温每升高一摄氏度，就可能从饱和空气团里多降7%的水。

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That means building futuristic structures that use wastewater and solar power to produce hydroponic (grown in a nutrient-rich water, without soil) and aeroponic (grown in water-saturated air) crops.

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These are boxes containing air that is super-saturated with water vapour.

ECONOMIST: Global warming

Without such particles, clouds would be rare: the air would need to be freakishly saturated with water vapour or strangely cold for condensation to occur.

ECONOMIST: Aerobiology