2.22 凝聚
Section outline
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This beautiful beaded net is something very common in nature: a spider web. The “beads” on the spider web are actually drops of water. The drops of water are not raindrops, and they weren’t there on the previous day. Where did they come from?
::这个美丽的珠子网在自然界非常常见:蜘蛛网。 蜘蛛网上的“珠子”实际上是水滴。 水滴不是雨滴,而是前一天的雨滴。 它们从哪来的?From Gas to Liquid
::从天然气到液体The drops of water on the spider web are dewdrops. They formed overnight when warm moist air came into contact with the cooler spider web. Contact with the cooler web cooled the air. When air cools, it can hold less water vapor, so some of the water vapor in the air changed to water. The process in which water vapor—or another gas—changes to a liquid is called condensation . Another common example of condensation is pictured in the Figure .
::蜘蛛网上的水滴是露水滴,当温暖潮湿空气与更冷的蜘蛛网接触时,它们一夜之间形成; 与更冷的网接触使空气冷却; 当空气冷却时,它能吸收较少的水蒸气,因此空气中的一些水蒸气变成了水; 水蒸气——或另一种气体——改变液体的过程被称为凝结过程; 图中描绘了另一个凝结的常见例子。This picture shows the contrail ( con densation trail ) left behind by a jet. Water vapor in its exhaust gases condensed on dust particles in the air.
::该图显示喷气式喷气机留下的抗体(凝结道),水蒸发器的废气凝结在空气中的粉尘颗粒上。Dew Point
::下点When air is very humid, it doesn’t have to cool very much for water vapor in the air to start condensing. The at which condensation occurs is called the dew point. The dew point varies depending on air temperature and moisture content. It is always less than or equal to the actual air temperature, but warmer air and moister air have dew points closer to the actual air temperature. That’s why glasses of cold drinks “sweat” more on a hot, humid day than they do on a cool, dry day.
::当空气非常潮湿时,对于空气中的水蒸气来说,它不必冷却太多才能开始凝结。 发生凝结的地方被称为露点。 露点因空气温度和湿度含量而异。 露点总是低于或等于实际的空气温度,但更暖和的空气和潮湿的空气的露点更接近实际的空气温度。 这就是为什么冷饮杯在炎热、潮湿的一天比冷干燥的一天更“润湿 ” 。Q: What happens when air temperature reaches the dew point?
::问题:当空气温度达到露点时会怎样?A: When air temperature reaches the dew point, water vapor starts condensing. It may form dew (as on the spider web in the opening image), clouds, or fog. Dew forms on objects on the ground. Clouds form on tiny particles in the air high above the ground. Fog is a cloud that forms on tiny particles in the air close to the ground.
::A:当空气温度达到露水点时,水蒸气开始凝结。它可能形成露水(如开阔图像中的蜘蛛网)、云或雾。在地面物体上形成阴暗形态。在地面高处的空气中微小颗粒上形成云。雾是靠近地面的空气中微小颗粒上形成的云。Condensation and the Water Cycle
::凝聚和水循环The water cycle continuously recycles Earth’s water. Condensation plays an important role in this cycle. Find condensation in the water cycle Figure . It changes water vapor in the atmosphere to liquid water that can fall to Earth again. Without condensation, the water cycle would be interrupted and Earth’s water could not recycle.
::水循环不断回收地球的水。 凝聚在这一循环中起着重要作用。 在水循环中找到凝聚点 图表 。 它将大气中的水蒸气改变为可能再次落到地球的液态水。 没有凝聚,水循环就会中断,地球的水也无法循环。Q: In the water cycle, what happens to water after it condenses?
::问:在水循环中,水凝结后会怎样?A: After water condenses, it may form clouds that produce precipitation such as rain.
::A:在水凝结后,它可能形成云层,产生雨水等降水。Summary
::摘要-
The process in which water vapor or any other gas changes to a liquid is called condensation.
::水蒸气或任何其他气体改变液体的过程称为凝结过程。 -
The temperature at which condensation of water vapor occurs is called the dew point. The dew point varies depending on air temperature and moisture content.
::水蒸气凝结的温度称为露点,露点因空气温度和水分含量而异。 -
Condensation plays an important role in the water cycle. Without it, Earth’s water could not recycle.
::凝聚在水循环中起着重要作用。 没有凝聚,地球的水就无法循环利用。
Review
::回顾-
What is condensation? Give an example.
::什么是凝聚?举个例子。 -
Define dew point. What factors influence dew point?
::确定露水点。哪些因素影响露水点? -
In the water cycle, how does water vapor in the atmosphere change to liquid water on the ground?
::在水循环中,大气中的水蒸气如何变成地面的液体水?
Resources
::资源 -
The process in which water vapor or any other gas changes to a liquid is called condensation.
