介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[12:21.23]The last reading.
[12:25.36]The Water Cycle
[12:27.97]The water cycle describes the continuous movement of water
[12:31.91]on, above and below the surface of the Earth.
[12:36.29]Although the balance of water on Earth
[12:38.50]remains fairly constant...

介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[12:21.23]The last reading.
[12:25.36]The Water Cycle
[12:27.97]The water cycle describes the continuous movement of water
[12:31.91]on, above and below the surface of the Earth.
[12:36.29]Although the balance of water on Earth
[12:38.50]remains fairly constant over time,
[12:41.35]individual water molecules can come and go,
[12:44.77]in and out of the atmosphere.
[12:47.75]The water moves from one reservoir to another.
[12:51.60]In so doing, the water goes through different phases:
[12:55.61]liquid, solid and gas.
[12:58.90]The water cycle involves the exchange of heat,
[13:02.43]which leads to temperature changes.
[13:05.18]For instance, when water evaporates,
[13:08.09]it takes up energy from its surroundings and cools the environment.
[13:13.43]When it condenses, it releases energy and warms the environment.
[13:19.02]These heat exchanges influence climate.
[13:22.28]By transferring water from one reservoir to another,
[13:26.34]the water cycle purifies water, provides the land with freshwater,
[13:31.47]and transports minerals to different parts of the globe.
[13:35.74]Finally, the water cycle plays a significant role
[13:39.37]in the maintenance of life and ecosystems on Earth.