Water, Water Everywhere!

If you were to travel into outer space and look back at the Earth, it would look blue. Earth is called the blue planet because it is mostly covered with water. In fact, over seventy percent of the surface is covered by ocean water.

The oceans contain ninety-seven percent of Earth's water. The other three percent is fresh water. This water is found on and under the ground. It is also contained in the polar ice caps. The atmosphere also holds a tiny fraction of Earth's fresh water.

Water on Earth is constantly changing states of matter. This happens during the water cycle. It can be a solid, which is ice. It can be a liquid. It can also be gas, which is water vapor. Water evaporates from oceans, lakes, and puddles, it condenses high up in the atmosphere, and then it falls back to Earth as rain, sleet, or snow. Even though the water on Earth is always moving, the total amount of water on Earth doesn't change. Water in a region can be tracked as it changes forms by something called a water budget.