Notes-Class 6th-Geography-Chapter-1-The Earth and The Graticule-Maharashtra Board

Topics to be Learn :

The Graticule
Angular Distance
Parallels of Latitude
Meridians of Longitude

The Graticule : The parallels and meridians on the globe form a net that is called a graticule . This facilitates determining the location of a place.

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Limitations of determining the location of a place on the earth :

Limitations of determining the location of a place on the earth :

Any monument is located at a particular place on the earth. However, when people from different places tell its direction from their respective places, their answers vary.
Thus, the use of directions and sub-directions alone does not help us to accurately describe the location of a particular place on the earth.
Therefore, it becomes necessary to use the exact system to state the precise location of any place on the earth.

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Earths huge size and making of a globe :

Earth's huge size and making of a globe :

The length of the east-west diameter of the earth is 12,756 kilometres and the length of the north-south diameter of the earth is 12,714 kilometres.
There are forests, uneven lands, and innumerable islands of different size, buildings, and oceanic waters on the surface of the earth. Therefore, to determine the location of a place. it is practically impossible to draw some horizontal and vertical lines on the earth.
In order to overcome this difficulty, geographers developed a miniature model of the earth. It is known as a globe. One can draw horizontal and vertical lines on a globe. Thus. a globe can be used to determine the locations on the earth.

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Angular distance :

Click here to View Figure-2

The location of any place on the earth is determined with reference to the centre of the earth.
Any point on the earth makes an angle with the plane of the equator. The measure of this angle is used in determining the location of that point.

Parallels of latitudes :

The east-west circles created at some angular distance from the centre of the earth are called parallels of latitudes.
The angular distances of all parallels are measured in degrees and are called latitudes
The parallels of latitudes are parallel to one another.
Parallels of latitudes are imaginary horizontal lines.

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Equator : The equator is considered as a 0° parallel. It is the largest parallel, and also known as a Great Circle.

Hemisphere : The equator bisects the earth into north and south parts. The one to the north is called the Northern Hemisphere and the one to the south is called the Southern Hemisphere.

Towards the north and the south of the equator, parallels of latitudes progressively become smaller and smaller in size but their angular value goes increasing.

North Pole and the South Pole : At the north and the south ends of the earth's axis, the parallels appear as points These are called the North Pole and the South Pole.

The total number of parallels on the earth :

The total number of parallels on the earth :

At 0°, there is the equator. One can draw 90 parallels in the Northern Hemisphere from 1° N to 90° N. Similarly, one can draw 90 parallels in the Southern Hemisphere from 1° S to 90° S.
Thus, one can draw 181 parallels on the earth at the interval of 1°. [1+90+90]

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Labelling of a parallel :

While labelling the value of a parallel, it is necessary to mention whether it is in the Northern Hemisphere or in the Southern Hemisphere.
Th6 parallels from the Northern Hemisphere are referred to as 5°N, 35°N, etc. Similarly, the parallels from the Southern Hemisphere are referred to as 5°S. 30°S, etc.

Meridians of longitudes :

The north-south semicircles created at some angular distance from the centre of the earth, are called meridians of longitudes.
The angular distances of all meridians are measured in degrees and are called longitudes.
Meridians of longitudes are imaginary vertical lines.

Click here to View Figure-4

0° Meridian : 0° meridian is also known as the Prime Meridian. The angular distances of the other meridians are measured from the Prime Meridian.

180° Meridian : 0° meridian and 180° meridian lie opposite on the globe, forming a circle, This circle divides the earth into east and west parts. The one to the east is called the Eastern Hemisphere and the one to the west is called the Western Hemisphere.

The total number of meridians on the earth :

The total number of meridians on the earth :

At 0°, there is the Prime Meridian. There is 180° meridian lying opposite to the
Prime Meridian. One can draw 179 meridians in the Eastern Hemisphere from
1° E to 179° E. Similarly, one can draw 179 meridians in the Western Hemisphere from 1° W to 179° W.
Thus, one can draw 360 meridians on the earth at the interval of 1°. (1+1+179+179 )

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Labelling of a meridian :

While labelling the value of a meridian, it is necessary to mention whether it is in the Eastern Hemisphere or in the Western Hemisphere.
The meridians from the Eastern Hemisphere are referred to as 10° E, 25° E, etc.
Similarly, the meridians from the Western Hemisphere are referred to as 10° W 25° W. etc.
0° meridian is known as the Prime Meridian. Therefore, 0° meridian is not labelled as 0° E or 0° W. It is labelled only as 0° meridian.

The distance between parallels and meridians :

The distance between parallels and meridians :

The distance between any two adjacent parallels is the same everywhere and it is 111 km.
The distance between any two adjacent meridians is not the same everywhere.
The distance between any two adjacent meridians is the maximum on the equator and goes on reducing towards the poles.
It is 111 km on the equator and zero at the poles.

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The values of parallels and meridians in degrees, minutes and seconds :

The values of parallels and meridians in degrees, minutes and seconds :

The distance between any two adjacent parallels is 111 km on the surface of the earth. Similarly, the distance between any two adjacent meridians is 111 km on the equator.
To locate the places within this distance of 111 km exactly, the unit of degree is further divided into minutes, and minutes are further divided into seconds.
Thus, conventionally latitudes and longitudes are expressed into degrees, minutes and seconds. Their values are expressed using the symbols of degrees (°), minutes (_') and seconds (_”) Example: 5°3’35” N etc..

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Various systems for determining locations on the earth :

Various systems for determining locations on the earth :

The method of latitudes and longitudes is used even in today’s modern age quite effectively for determining locations.
Geographical Information System (GIS), Global Positioning System (GPS), Google Maps, Wikimapia, etc. are some other systems for determining locations. All these systems make use of latitudes and longitudes for determining the locations on the earth.

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Indian Regional Positioning system :

Indian Regional Positioning system :

India has achieved self-reliance in Global Positioning Technology.
With the help of IRNSS (Indian Regional Navigation Satellite System). locating any place in the Indian subcontinent, in the region of South Asia and in the Indian Ocean is going to be easy.
For this. India is launching its own series of 7 satellites.

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