The painting illustrates how water travels from the ocean to the air and then to land in a natural process called the water cycle. The three main stages are shown on the diagram. Seawater evaporates, falls as rain and eventually flows back into the ocean. Starting from the evaporation phase, we can see that 80% of the water vapor in the air comes from the oceans. The heat of the sun causes water to evaporate, and the water vapor condenses to form clouds. In the second stage, labeled 'precipitation' on the diagram, water falls as rain or snow. In the third stage of the cycle, rainwater can follow many different paths. Some may fall into lakes or return to the ocean through 'surface runoff'. Otherwise, rainwater can filter through the ground, reaching the impermeable layer of the earth. Saltwater intrusion is believed to occur just before groundwater flows into the ocean to complete the cycle.
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