DAV Class 7 Geography Chapter 5 Water surrounding the earth

1. WATER
SURROUNDING THE
EARTH
BY KAMLESH KHANNA

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

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

6. WHAT IS WATER CYCLE?

7. THE PROCESS OF WATER CYCLE

13. VARIOUS MOVEMENTS OF OCEAN WATER

14. 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.

15. OCEAN CURRENTS

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

17. Solar heating

18. 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.

19. Coriolis force

20. Winds

24. 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.

27. TIDES

28. Causes of tides

29. 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

30. Effects of Tides

32. 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.

33. 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.

34. 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.