Well... Today, some of us begin to become ecologist. We are going to speak about the water cycle, to understand how can we save the water, maybe the main issue of this century.
Because it's a cycle, we need to arbitrary chose a start point!
First, a large amount of water is available in seas and oceans. Under the warm of the sun, the water evaporates and becomes invisible to us (water steam is not visible).
Then, when molecules of water are cooled by a upper cold atmosphere, they condense in big clouds.
Next, the wind pushes theses clouds over a continent. The next step is precipitations in two main ways : snow and rain. The first one when the water is under 0 degree, the other when it is over. The snow is usually store on mountains. The rain is everywhere else.
Subsequently, the precipitations are divided in two parts : surface run-off (rivers, lakes...) and ground water which infiltrate the ground.
The next stage is the return of all this water into the sea by the gravity action. Simultaneously the water in the surface evaporates(liquid to steam) or sublimates(solid to steam) in part and regenerates a bit the clouds.
Finally we are is the start point, the sea or ocean!
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