Class 7 chapter_5_water_surrounding_the_earth

DAV Class 7 Geography Chapter 5 Water surrounding the earth

1. WATER SURROUNDING THE EARTH BY KAMLESH KHANNA

2. Oceans are the largest reservoirs of water on the earth

3. Major five oceans of the world P A I S A

4. WHAT IS WATER CYCLE?

5. THE PROCESS OF WATER CYCLE

6. VARIOUS MOVEMENTS OF OCEAN WATER

7. WAVES A wave is an up and down movement of the ocean surface.It is important to note that water actually does not travel with the wave. Most waves are caused by wind . When the wind blows, it pushes on The Ocean surface, causing the water to lift. The height of a wave depends on the speed of wind and the duration of wind blowing from a particular direction. Together, it determines the size of a wave.

8. OCEAN CURRENTS

9. The ocean currents originate due to Solar heating Difference in density of oceanwater. The rotation of the earth. The Planetary winds.

10. Solar heating

11. Difference in density of oceanwater Cold water is denser than the warm water. Due to the higher density of cold water, it sinks down below the warm water. Thus, the cold water of the polar region moves slowly towards the equator along the bottom of the ocean. The warm water near the equator moves along the surface of the ocean towards the poles.

12. Coriolis force

13. Winds

14. Effects of ocean currents Warm ocean currents and cold ocean currents affect weather and climate in different ways. Regions near warm ocean currents are often warmer and wetter than regions near cold ocean currents. Areas where the warm and cold currents meet provide the best fishing grounds of the world.Ex. seas around Japan and the eastern coast of North America. The ocean currents help in navigation.

15. TIDES

16. Causes of tides

17. Types of Tides SPRING TIDES Rise very and fall very low. New moon days and full mood days. Sun, moon and earth are in straight line NEAP TIDES Neither rise very high nor fall very low. Quarter moon days Sun, moon and earth are in right angle

18. Effects of Tides

19. Importance of oceans to man The ocean is one of Earth's most valuable natural resources. the oceans facilitate countries and regions to trade with one another. cheaper than any other mode of transport. plant life for food and trade in abundance. The valuable mineral resources are found in the ocean floor example Mineral oil, manganese, gold, platinum, copper and cobalt.

20. Case study of Tsunami Huge sea waves are called Tsunami which is a Japanese name. These waves are caused by the earthquake, underwater volcanic eruption or any other such severe disturbance. 26 December 2004, gigantic waves, crashed into the coastal region in many parts of the world, washing away people, animals and homes. There were unprecedented losses and the whole world watched in horror.

21. Government agencies, Non-Governmental Organisations and Resident Welfare Associations, business organisations, shopkeepers, schools and colleges provided relief to the victims by donating money clothes medicines beddings tents etc. Media played an important role in mobilising public help for the victims.