7.Chapter5.Geography.Water Surrounding the Earth

Chapter 5.

Water around us.

Keywords.

Fishing ground :  An area   in the oceans and seas where fish are in plenty and fishing is usually good. 

Plankton: microscopic organisms that drift in the upper water of the sea.  Most marine creatures depend upon them directly or indirectly for food. Plankton rich zones in the ocean make good fishing grounds. 

Stream flow : a portion of run off that enters the river valleys to move towards the oceans. 

Surface run off : the part of total precipitation that flows over the ground. 

Transpiration : the transfer of water vapour to the air from plants. 

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Something to Know

A. Tick ( ) the correct option. 

1. The water cycle is –

(a) the continuous movement of water. 

(b) passage of water through a house. 

(c) the life of an organism in water. 

(d) a static system

2. The three states of water are

(a) cloud, rain, river

(b) solid, liquid, gas

(c) salt water, fresh water, rain water

(d) waves, tides, currents

3  What turns water on the earth into vapours in the water cycle? 

(a) the core of the earth

(b) global warming

(c) the sun

(d) nuclear energy

4 When clouds get too heavy to hold water

(a) the water runs off. 

(b) the water falls on the earth. 

(c) more clouds are formed. 

(d) Water gets collected. 

5.  In coastal areas, warm ocean currents cause

(a) low temperature

(b) rainfall

(c) dryness

(d) global warming

B. Fill in the blanks. 

1. The largest natural source of water is rain.

2. When the level of ocean water rises, it is a high tide. 

3.  Kolkata  port in India is an example of tidal port. 

4.  Tidal energy is a  renewable source of energy   

5.  Cold currents flow along the west coast of the oceans. 

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C. Give a technical term for each of the following statements. 

1.  The process in which water is converted to water vapors through heat of the sun Ans Evaporation

2 .The continuous circulation of water in the three spheres of the earth.

Ans Water Cycle.    

3.  A movement in the ocean in which water particles move up and down. 
Ans Wave

4.  It is the purest form of water. 
Ans Rain water.

5.  Periodic rise and fall in the level of the ocean water, 
Ans Tide

D. Answer the following questions in brief. 

1.  On what factors does the height of a wave depend?

Ans The height of the waves depend upon the speed of wind,the duration of the wind that blows in a particular direction. 

2.  Define an ocean current.

Ans.The ocean current is the regular movement of a mass of water in a specific direction.

It is of two types a.Cold currents b.Warm Currents. 

3. How are tides caused?

Ans.Tides are the periodic rise and fall in the level of ocean water.These are caused due to the gravitational pull of the moon and sun. 

4.  Name the important components of the water cycle.

Ans.The main steps  of water cycle are evaporation,transpiration,condensation,precipitation and surface runoff. 
The main sources are the heat of the Sun,water sources as ponds,rivers and oceans are the important components of the water cycle.

5. Name three valuable resources which are found in abundance in the ocean.

Ans. Oceans are the treasure of some of valuable resources that are found in the oceans floor.

These are important minerals found inside the floor of the oceans.
Oil,Manganese,Gold,Platinum,Nickel,Copper,and Cobalt etc. 

E. Answer the following questions. 

1. How are tides useful to us? 
Ans : Tides occur twice in a day with a high tide and a low tide. A high tide enables big ships to enter the harbour.Kolkata is a tidal port an example in India.
It is  one of the important renewable sources of energy.Nowadays the tidal energy is harnessed to generate electricity. 
2. How are oceans beneficial to us in improving the quality of life? 

Ans : Oceans provide us the water ways for the transportation of the essential goods.Such a transportation remains very cheaper than any other mode.
The marine environment provides the homes for the animals and different plants.
Oceans are the treasure of different mineral resources like oil,manganese,gold,platinum,nickel,copper,and cobalt.
3. Explain the water cycle with the help of a diagram. 

Ans : The sun due to its heat causes water to evaporate.
The evaporated vapours rise up and condense into tiny crystals of droplets and ice.
When the condensed ice crystal or water droplets grow in size fall down over the earth,as they remain unable to float more in air.
Falling down over the earth is known as precipation.
Such a process runs endlessly is described as the water cycle.

Picture of water cycle.

4.  Explain three effects of ocean currents. 

Ans : These are the three effects of the occean currents.
warm current raises the temperature and makes the places warmer than the surrounding area.
Similarly the cold current makes the adjoining area colder.It makes the climate cool and comfortable.
Warm current causes the rainfall that influences the climate.Then the climate stays warm and moist.
These currents serve as major fishing grounds, encouraging trade and commerce.
The confluence of cold and warm currents provide the ideal conditions for plentiful growth of plankton that is a food item for the marine lives.
5. Suggest four ways to help people affected by devastation due to Tsunami.

Ans : Tsunami always devastates the major areas.
We should take care of environmental and ecological balance.
We should give ample donations in the PM relief fund can be utilised for the facilities provided to victims in Tsunami.
Habitats should be provided for the effected persons in Tsunami.

Value Based Question

We should respect and protect our oceans and seas.  Oceans made Earth a habitable planet by giving birth to life.  But we are turning our oceans into dumping grounds of waste material. 

What steps should be taken to prevent loss of precious marine life?  Give two suggestions to ban the disposal of waste material into oceans and seas.  . 

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Map Skill

Locate and label the following on the outline map of the world. 

(a) Labrador Current

(b) Gulf Stream

(c) North Atlantic Drift

(d) Grand Banks Fishing Ground

(e) Dogger Banks Fishing Ground

Something to Do

1. Prepare a small working model of ocean currents over a thermocol sheet.  Use colored electric wires to show distribution of cold and warm currents. 

2. Collect pictures of the different marine resources present in the ocean. 

3. Collect pictures of a coastal region showing devastation of land, trees, houses and lives caused huge oceanic waves. 

4. Collect pictures of coastal region in India where corrective action has been taken to preserve water and natural vegetation and wildlife. 

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