SST (VI)-LESSON-1 LOCATING PLACE ON THE EARTH (LESSON NOTES)

 

SST (VI)-LESSON-1

LOCATING PLACE ON THE EARTH

(LESSON NOTES)

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v INTRODUCTION

Ø Imagine that you are visiting a city for the first time. How would you find the places you want to visit? You might ask a local person for help, or you might look at a map of the city.

Ø So, in this lesson we will find the answers of these questions as

§  What is a map and how do we use it? What are its main components?

§  What are coordinates? How can latitude and longitude be used to mark any location on the Earth?

§  How are local time and standard time related to longitude?

 

v MAP

Ø A representation or a drawing of the Earth’s surface or a part of it drawn on a flat surface according to a scale is known as Map. Book of maps is known as  Atlas.

v COMPARISION OF MAP AND  GLOBE

GLOBE	MAP
Globe is used to study the whole Earth.	Map is used to study the whole Earth as well as its part.
It is not easy to carry.	Maps are easy to carry.
Globe is three three-dimensional sphere.	Map is a simple drawing on paper.

v TYPES OF MAPS

There are mainly three types of maps-

v PHYSICAL OR RELIEF MAPS

Ø The map which shows natural features of the earth like Mountains, rivers, plateaus, plains, rivers, oceans etc. are called physical or relief maps.

v POLITICAL MAPS 

Ø The Maps which showing cities, towns and villages, and different countries and states of the world with their boundaries are called political maps.

v THEMATIC MAPS

Ø The maps which focus on specific information; such as road maps, rainfall maps, maps showing distribution of forests, industries etc. are known as thematic maps.

 

v COMPONENTS OF MAPS

There are three components of maps—distance, direction and symbol.

v SCALE OR DISTANCE

Ø The ratio between the actual distance on the ground and the distance shown on the map is known as scale.

 

v By the scale we can calculate the distance between any two places on a map.     

v For example, the distance between your school and your home is 10 km. If you show this 10 km. distance by 2 cm on a map, it means, 1 cm on the map will show 5 km. on the ground. The scale of your drawing will be 1cm = 5km.

LARGE SCALE	SMALL SCALE
It is used to show small area like village or town in map	It is used to show large area like continents or continents in map.
It provide more information	It provide less information
Example- 5 cm=500 km	Example- 5 cm=500 m

 

v DIRECTION

  Ø Every map contains an arrow marked with the letter ‘N’ at the upper right hand corner. This arrow shows the north direction. It is called the north line.

  Ø There are four major directions, North, South, East and West. They are called cardinal points.

  Ø There are four intermediate directions—north-east (NE), south-east (SE), south-west (SW) and north-west (NW)

    Ø We can find out the direction of a place with the help of a

magnetic compass. 

 

 v SYMBOLS

  Ø The certain letters, shades, colours, pictures and lines used on maps to show the different features as such as buildings, roads, bridges, trees, railway lines or a well of the Earth are called as conventional symbols.

  Ø These symbols are internationally approved. 

  Ø The conventional symbols give a lot of information in a limited space.

  Ø  The blue colour is used for showing water bodies, brown for mountains, yellow for plateau and green is used for plains.

v Mapping the Earth

  Ø Mapping the Earth is a little difficult because our planet is not a flat surface. It nearly has the shape of a sphere that is slightly flattened at the poles. It is called as Geoid.

  Ø Here we will study the globe representing the Earth’s geography. Because the globe and the Earth have the same spherical shape.

  Ø GLOBE:- The true model of the earth is called as globe. It can be rotate like Earth. On the globe, countries, continents, and oceans are shown in their correct size.

  Ø Understanding Coordinates

§  Coordinates are the place which are related to a stationery place. For example, if you ask your friend Meet me at 6 pm at the 7th shop in the 5th row from the entrance. Same as in chess board your pawn as on d2.

§  A similar system of coordinates is used in the world of maps to determine the location of any place on a map.

  v PARALLELS OF LATITUDES

Ø All parallel lines from east to west around the Earth are called as Latitudes. Latitudes are measured in Degrees. There are 180 latitudes lines. 0 degree latitude lines is largest. As we move away from this 0 degree latitude, the size of the parallels of the latitude decreases.

v IMPORTANT PARALLELS OF LATITUDE

  Ø Equator(0°)

  §  The 0 degree latitude line which divides the earth into two equal parts running through the middle of the globe is called Equator. It divided the earth into 2 equal parts as Northern Hemisphere and Southern Hemisphere.

  Ø Tropic of Cancer (23½° N) in the Northern Hemisphere

  Ø Tropic of Capricorn (23½° S) in the Southern Hemisphere

  Ø Arctic Circle at 66½° north of the equator

  Ø Antarctic Circle at 66½° south of the equator

  Ø The North Pole (90°N)

  Ø  The South Pole (90° S)

LATITUDE AND LONGITUDES

  

v HEAT ZONES OF THE EARTH

    

                   

 

  v LONGITUDES OF THE EARTH

  Ø The lines which runnings from the North Pole to the South Pole are called meridians of longitude.

  Ø Features of meridians of longitudes

       § Longitudes are measured in degrees and each degree is further divided into minutes, and minutes into seconds.

  §  They are semi-circles and the distance between them decreases steadily toward poles.

  §  All the meridians are of equal length.

 

  Ø Prime meridian (Greenwich Line). 

  §        The meridian which passed through Greenwich, where the British Royal Observatory is located is called the Prime Meridian (Greenwich Line). Its value is 0° longitude.

  §  The Prime Meridian divides the earth into two equal halves, the Eastern Hemisphere and the Western Hemisphere.

  §  180° East and 180° West meridians are on the same line. It is known as International Date Line.  

 

  Ø LONGITUDE AND TIME

§              The local time is decided by the position of Sun on the Earth.

§  The international time is decided according to the Greenwich line.

  §  As the earth rotates from west to east, those places east of Greenwich will be ahead of Greenwich Time and those to the west will be behind it.

  §  The rate of difference can be calculated as follows.

   The earth rotates 360° in about 24 hours, which means 15° an hour or 1° in four minutes.

 

  v NEED FOR STANDARD TIME

  Ø The local time of the places are different.

Ø So it will be difficult to prepare a time-table for trains which cross several longitudes.

  Ø Indian Standard Meridian

  §  In India there will be a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam.

  §  It is, therefore, necessary to adopt the local time of some central meridian of a country as the standard time for the country.

  §  In India, the longitude of 82½° E (82° 30'E) is treated as the standard meridian.

  §  The local time at this meridian is taken as the standard time for the whole country. It is known as the Indian Standard Time (IST).                                                                                                              

Ø Some countries have a great longitudinal extent and so they have adopted more than one standard time.

§  For example, in Russia, there are as many as eleven standard times.

§  The earth has been divided into twenty-four time zones of one hour each. Each zone thus covers 15° of longitude