The Water cycle Where does the water come from, where does it go, and what does it do when it gets there?

The Water Cycle When Sir Isaac Newton tossed an apple in the air he observed “What goes up, must come down.” The same could be said for the water cycle. We could also add, “What comes down, must go up.”

The Water cycle has no beginning, and no end. Water has been moving up, down, and all over our world since we have had water on our planet.

Where did we get all of this water?

The water on our planet has been here for a very long time. There are several theories on where it came from.

Some say that it came from the volcanic activity back when our planet first formed. At this point our planet is covered in lakes of lava, and is full of volcanoes.

When volcanoes erupt they release many different types of gasses. Two of which are Hydrogen, and oxygen.

When the oxygen released from the volcano combined with the hydrogen in the air it made water.

When two molecules of hydrogen bond with one molecule of oxygen it forms a single molecule of water. That is why water is sometimes referred to as H 2 O.

The other theory is that the water came from outer space. Some scientist think that a comet, or several comets, crashed into our planet when it was very young.

The ice from the comets melted and in time formed the oceans, lakes, and rivers.

How much water do we have?

We have an estimated 332,500,000 cubic square miles of water on our planet. Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp

How much water do we have? If I were to build a box. Making it one mile tall, one mile wide, and one mile long, and filled it with water, that would be one cubic mile of water.

Now build 332,500,000 more boxes and you have our worlds water supply. But you can’t drink it all?

Of the 332,500,000 million cubic square miles of water only 2 ½ percent is drinkable. Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp

How much water do we have? Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp There is an estimated 8,400,000 million cubic square miles of fresh drinking water on our planet.

How much water do we have? An estimated 75% of the fresh water on our planet is frozen at the north and south poles, in the form of glaciers.

That is to say that 6,300,000 cubic square miles of fresh water is frozen at the poles.

That leaves approximately 2,100,000 cubic square miles of fresh potable drinking water on our planet, for all living things to drink.

What is the water cycle?

At its core the water cycle has four steps: Evaporation Condensation Precipitation Run Off

Evaporation, occurs when the sun shines on our rivers, lakes, and oceans, causing the water to evaporate and turn into vapor. Evaporation Transportation Condensation Precipitation Run Off

Evaporation means when water is turned into water vapor. Or when a liquid is turned into a gas. Evaporation

The water vapor begins to rise up through the atmosphere. As it gets higher in the air, the air cools and the water vapor begins to condense. Condensation

When a gas condenses it turns from its gaseous form to a liquid form. In this case from water vapor, into tiny droplets of water.

What is the water cycle? These droplets then form clouds in the sky. As the air gets cooler the droplets get bigger, until the wind can no longer hold them up. They begin to fall to the ground.

When water falls to the ground it is called precipitation. Precipitation Condensation

We commonly think only of rain as precipitation, but snow, sleet, hail, and even fog are all forms of precipitation.

When the rain hits the ground, the ground begins to absorb the water. This is known as saturation. Precipitation Saturation or Run Off

Saturation reefers to how much water is being held in the ground.

Once the ground is totally saturated and can not hold any more water, it will begin to pool into puddles.

The water begins to run off into rivers and streams. Rivers and streams flow into larger bodies of water such as lakes, and oceans.

Once precipitation stops and the clouds clear, the sun comes out, and begins to evaporate the water on the ground.

And so the water cycle renews. It has no beginning and no end. It simply is...