2. Water and Weather

3. Chapter Four: Water and the Water Cycle
4.1 Water on Earth’s Surface
4.2 The Water Cycle

4. Investigation 4A The Water Cycle
How is a model of the water cycle in your classroom like the Earth’s water cycle?

5. 4.1 Water on Earth’s Surface
About 70 percent of Earth’s surface is covered with water.
This water is found in oceans, rivers, lakes, under the ground, and as ice.

6. 4.1 The hydrosphere
All the water on Earth is part of a large system called the hydrosphere.
On Earth, water occurs in all three phases.

7. 4.1 The distribution of water on Earth
About 97% of Earth’s water is salt water found in oceans.
If all the water on Earth could fit into a one-liter bottle, only 17 milliliters would be fresh water.

8. The distribution of water on Earth

9. 4.1 Places where water is found
Surface water on Earth refers to water that collects on the ground.
This water includes oceans, lakes, rivers, streams, and reservoirs.
A reservoir is a protected artificial or natural lake that is used to store water.

10. 4.1 Places where water is found
A glacier is a huge mass of ice that forms on land when snow and ice accumulate faster than they melt.
Most of Earth’s fresh water is in the form of glacier ice.

11. 4.1 Places where water is found
Groundwater is water that collects under ground.
Some of the water on Earth’s surface moves down through the soil to the water table (the upper level of underground water).

13. 4.1 Water as a resource
The temperature range on Earth’s surface is just right for water to exist in all three phases—liquid, solid, and gas.

14. 4.1 Water as a resource
One of the reasons why water is so useful is that it can dissolve many things.
Water dissolves nutrients found in food, gases such as oxygen, and minerals found in rocks.

15. 4.1 Water as a resource The human body is 60% to 75% water.
When you eat food, water in your body dissolves nutrients so they can be carried through your bloodstream.

16. 4.1 Uses for water
Water is necessary for all forms of agriculture and farming.
For example, water is needed to grow grain for bread and to grow fruits and vegetables.
Water is also used in industry and in many ways in your home.