Linda Bateman, age 11, of Oilton, Okla., for her question:
What is the water cycle?
Our luxury planet is kept going by the laws of Nature. The earth, the atmosphere, the plants and animals all obey these laws without question, only man can question them and maybe disobey them. And only man can understand and truly appreciate them.
Nature's laws are usually simple and smooth running. Many of them run in cycles. The animal world breathes oxygen and returns waste carbon dioxide to the air. The plant world uses the carbon from this carbon dioxide and returns fresh oxygen to the air for the animal world to breathe. This is the oxygen cycle. There is also a nitrogen cycle and a carbon cycle. There is also a water cycle and all of them work on a grand world wide scale.
Most of the world's water supply is in the oceans. Every plant and animal on land needs a daily drink of fresh water, not salty ocean water. Nature solves this problem with the water cycle. It consists of a powerhouse an up elevator, a flying carpet services a down elevator and countless storage bins.
The powerhouse is the sun. It smiles down on the sear on rivers, lakes puddles and the damp soil. Its warm smile excites the tiny water particles near surface. Countless numbers of them take off into the air and become gaseous water vapor. The salty minerals in the sea are usually too heavy to evaporates so the rising water vapor is pure and fresh.
The smiling powerhouse also warms the air. Warm air rises taking its quota of water vapor with it. Up goes the elevator. Once aloft, the warm air coop and cool air must give up some of its gassy vapor. This vapor becomes a cloud of misty droplets ‑ a flying carpet.
The breezes blow the clouds over hill and dales. Vapor taken from the sea is moved over the land. Sooner or later the flying carpet becomes too heavy to stay aloft. The fine droplets gel into rain drops. Then the down elevator goes into operation. This is the power of gravity which hugs all heavy objects to the face of the earth. It pulls on the heavy clouds, and down spills the rain.
Some of the rainfall tumbles right back into the sea. Some runs down stony slope, gathering into streams. The streams meet to form rivers and the rivers flow back to join the sea. But a good deal of the rainfall sinks down through the soft soil into the rocky crust of the earth. There it is trapped in beds of gravel, in cracks and crannies. It becomes ground water.
Ground water is trapped in countless storage tanks below the surface. Some of it feeds the deep roots of the trees. When we dig a well, we reach down to it, and water seeps into the hole. Sometimes ground water breaks out in a spring. A good deal of it flows underground and finally joins a river which takes it back to the sea.
Every days millions of tons of water are evaporated from the sea and somewhere else millions of tons of water fall back to the earth as rains, snow, hail or sleet. This is the water cycle which provides a never ending supply of fresh water to the thirsty plants and animals.