What is the water cycle?

April 23, 2008 1:13:29 PM PDT
The water cycle is the natural movement of water in our ecosystem. The water cycle not only involves the way water gets transported, but also the different types, or phases, of water (i.e., solid, liquid and gas).

Erica's Answer:

The water cycle has 4 stages: Evaporation, Condensation, Precipitation, and Collection. In order to simplify, I'll focus on the water cycle for rain, though it's pretty much the same for all types of precipitation.

Evaporation is when liquid water (in rivers, lakes, ponds, oceans, puddles, etc.) turns into gas. This gas, called water vapor, rises and cools, which leads to the next step.

Condensation occurs when water vapor cools down so much that it cannot remain in gas form anymore- it loses too much heat energy. So, it forms into tiny liquid water droplets that we see as clouds. Eventually, these clouds will become so thick and heavy with tiny water droplets that they need to go somewhere, leading to the next step.

Precipitation (in this case, rain) will fall from a cloud down into the atmosphere below. Some of the rain gets soaked up into the ground, helping plants grow. Some other rain moves further below the Earth's surface, ending up in underground lakes and rivers called aquifers. The rest of the water enters the final stage of the water cycle.

Collection occurs when the precipitation enters any body of water in which it unites with other raindrops. This could be as big as the Atlantic Ocean, or as small as your swimming pool.

The water cycle continues and repeats itself when the collected water evaporates back into the atmosphere!

- Erica


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