Chapter 11 Fresh Water

11.1 The Water Cycle Identify how Earth’s water is distributed among saltwater and freshwater sources. Describe how Earth’s water moves through the water cycle.

Engage/Explore Have a student describe a rainstorm. Where does the water come from that falls as rain? How does the water get into the clouds?

Discover - Where Does the Water Come From? Fill a glass with ice cubes and water, being careful not to spill any water. Wait 5 minutes. Observe the outside of the glass and the surface it was sitting on.

Introduction - Notes Why is Earth called the “water planet”? From space, this is the image that astronauts see. Oceans cover nearly 71 percent of Earth’s surface.

I. Water on Earth - Demo

Most of Earth’s water is 97% percent salt water that is found in oceans. Only 3% is fresh water. 76% ice masses .037% atmosphere (water vapor in a gaseous form. Less than 1% is fresh water available for human use. Some of the Earth’s fresh water is deep underground.

A. Oceans All Earth’s oceans are connected to form a single world ocean.

B. Ice - Artic and Antarctica Icebergs are formed from frozen fresh water.

C. Rivers and Lakes - St. Lawrence Seaway to the Great Lakes

D. Below Earth’s Surface Groundwater - water that fills the cracks and spaces in underground soil and rock layers . Far more fresh water is located underground than in all Earth’s rivers and lakes.

II. The Water Cycle Water Cycle - the continuous process by which water moves through the living and nonliving parts of the environment. All the water on Earth has been through the water cycle.

II. The Water Cycle In the water cycle, water moves from bodies of water, land, and living things on Earth’s surface to the atmosphere and back to Earth’s surface. The sun is the source of energy that drive the water cycle. Prentice Hall video and activity

A. Water Evaporates Exploring the water cycle p. 363. Evaporation - the process by which molecules at the surface of a liquid absorb enough energy to change to the gaseous state. Ocean water that evaporates isn’t salty because the salt remains in the ocean.

Plants Plants take in water by drawing in water form the soil through their roots. Transpiration - water given off through the leaves as water vapor. Plants give off a large amount of water.

B. Clouds Form Condensation - clouds form when condensed droplets of water clump together around tiny dust particles in the air, forming clouds. Water vapor condenses when it travels up in the air because the air is colder. Cold air holds less water vapor than warm air, so some of the water vapor condenses.

C. Water Falls as Precipitation Precipitation - water that falls to Earth as rain, snow, hail, or sleet. Precipitation occurs when water droplets in a cloud grow larger and larger. They become so heavy that they fall to Earth.

Most water falls in the ocean which may stay there for many years. Some water falls on land & evaporates immediately. Some water runs off into rivers and lakes. Some water trickles down into the ground.

Precipitation is the source of all fresh water on and below Earth’s surface. The water cycle renews the usable supply of fresh water on Earth. The total amount of water on Earth has remained fairly constant and balanced. Water cycle song - “Clementine”

Questions What are the three processes in the water cycle? Answer: evaporation, condensation, precipitation Which process begins the cycle? Answer: a cycle has no beginning and no end. The water cycle is continuous.

How Do People Use Water?

Ch. 11.2 Icebergs - p. 376 P. 376 in text Titanic movie clip

Icebergs Titanic movie clip Glaciers move over land and when they hit water they become an iceberg. 10,000 form every year from Greenland. Only about 10 percent of an iceberg is visible. 90% of an iceberg lies below the surface.

Iceberg The underwater part is a hazard to ships because it is often much wider than the visible part of the iceberg. The International Ice Patrol is now set-up to track icebergs.