A cloud is a condensation of water vapour in the atmosphere.

云是由大气中的水蒸气凝结成的.

《现代汉英综合大词典》

Clouds are formations of condensed water vapour.

云是由凝聚的水蒸气构成的.

《简明英汉词典》

Water vapour condenses to form clouds.

水蒸气凝结形成云。

辞典例句

When water changes to water vapour, we say it evaporates.

当水变成水蒸气时, 我们把这个过程叫做蒸发.

英语晨读30分（初三）

When water vapour changes to water, we say that it condenses.

当水蒸气变成水时, 我们把它叫做冷凝.

英语晨读30分（初三）

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

这是一些装有水汽过饱和空气的容器.

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This water vapour rises, condenses on cooling, and falls as rain.

水蒸汽升入空中, 遇冷凝成雨滴而下降.

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Humidity: Quantity of water vapour in unit volume of air.

湿度: 在单位容积内的水气数量.

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This causes more and more water vapour to condense.

这就使越来越多的水蒸气凝结.

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There are nitrogen, oxygen, a little carbon dioxide and water vapour.

它们分别是氮气, 氧气, 少量的二氧化碳和水蒸汽.

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That moves out from the stomata is oxygen and water vapour.

而走出气孔的气体是氧气和水蒸气.

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To allow the water vapour to escape from the crucible.

容许水汽从坩埚中离开.

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Quantity of water vapour in unit volume of air.

在单位容积内的水气数量.

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Compressed air entering the air net is always 100 % saturated with water vapour.

通常进入空气网的压缩空气都含有百分之百的水蒸汽.

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The water vapour from her breathe condensed on the cool window.

她呼出的水蒸气在冰冷的窗户上凝结成了雾.

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