DISCUSS WATER SOURCES.

Hydrosphere

Life on earth is dependent on water. As you know, water can be found in the air, the ground, streams, rivers, and oceans, as well as in all living things, including you. The water that is found in living things is called biological water. Clean water is critical to our survival. In this segment of the lesson you will learn where the earth's water is stored. As you might know, there are many government organizations that monitor and evaluate our natural resources, including water. The following information was produced by the United States Geological Survey.

Where is Earth's water located?

Water is continually moving around, through, and above the earth as water vapor, liquid water, and ice. In fact, water is continually changing its form. The earth is, for the most part, a "closed system" like a terrarium, which is a transparent container that is used to create a miniature, self-contained ecosystem. That means that the earth, as a whole, neither gains nor loses much matter, including water. Although some matter, such as meteors from outer space, are captured by Earth, very little of Earth's substances escape into outer space. This is certainly true about water, which means that the same water that existed on Earth millions of years ago is still here. Thanks to the water cycle, the same water is continually being recycled all around the globe. It is entirely possible that the water you drank for lunch was once used by Mama Allosaurus to give her baby a bath.

By the way, there is a theory that much of Earth's water came from comets hitting the planet over billions of years.

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. For more information about this and other OCW projects at BYU, visit http://ocw.byu.edu.