Water exists on Earth in various forms that make up the hydrosphere, including rivers, lakes, oceans, glaciers and underground water. Rivers flow from their source in the upper course, develop meanders in the middle course, and empty into another body of water at their mouth in the lower course, receiving water from tributaries along the way. The Nile River is over 6,853 km long and flows north from tropical Africa to the Mediterranean Sea.

1. Water on Earth: THE HYDROSPHERE
UNIT 3

2. reservoir

3. river
discharge

4. upper course
middle course
lower course
source
mouth

5. length6.853 km

6. meanders

7. tributary

8. salt water
Types of water:
fresh water

9. precipitation

10. water cycle