SCIENCE CHAPTER 6 WATER CYCLE AND WEATHER

1. SCIENCECHAPTER 6WATER CYCLEAND WEATHER

2. Where is Earth’s Water ? Lesson 1

3. Lesson 1 • ¾ of Earth’s surface is covered with water. Ocean Water/Fresh Water • Ocean water is very salty. It is not healthy to drink. • Fresh water is found underground, or in lakes, rivers, and streams.

4. Lesson 1 • The ocean is less salty in areas where there are rivers, melting ice, or heavy rains that add plenty of fresh water. • The Baltic Sea is less salty because many rivers flow into it.

5. How do water and air affect weather? Lesson 2

6. Lesson 2 • The never-ending movement of water from Earth’s surface to its atmosphere is the water cycle. • The Sun’s purpose in the water cycle is to evaporate water. • When moist air rises, it cools and the water vapor in it condenses and forms clouds.

7. Lesson 2 • Condensation is the process of water vapor, a gas, changing to a liquid as it cools. • Air is a mixture of invisible gas that surrounds Earth. • If there is air near an area of low pressure that air will move toward the area of low pressure • Air pressure decreases as you go higher in the atmosphere. • Air pressure becomes lower

8. What are air masses? Lesson 3

9. Lesson 3 • Humidity is the amount of water vapor in the air. • The area where two air masses meet is called a front.

10. Lesson 4 • There are two types of fronts: cold front, warm front • Cold fronts form when a cold air mass bumps into a warm air mass that is not moving at all. The dense cold air sinks. The warm air is pushed upwards. Water vapor condenses into clouds. Clouds will usually form in a line along a cold front.