GEOGRAPHY (VI)-LESSON 2 GLOBE-LATITUDE AND LONGITUDE (LESSON NOTES)

GEOGRAPHY (VI)-LESSON 2

GLOBE-LATITUDE AND LONGITUDE

(LESSON NOTES)

____________________________________________________

v INTRODUCTION

Ø The shape of the earth is Geoid which means it is slightly flattened at the North Pole & South Pole.

Ø So Globe is the true miniature form or the model of our earth. In this lesson we read completely about the globe, its lines and also correlate with time.

v GLOBE

Ø 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.

GLOBE

v FEATURES OF GLOBE

Ø Globe can rotate on its axis like the earth.

Ø It is tilted 23.5 degrees from a vertical 90 degrees.

Ø It is inclined by 66.5 degrees from the earth's orbital plane,

v AXIS-

Ø A needle is fixed through the center of the globe in a tilted manner, which is called as axis.

Ø Earth's axis is an imaginary line which passes through the North Pole and South Pole around which the earth spins. Earth moves from West to East.          

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

Ø Torrid Zone

§  The zone between the Tropic of Cancer and the Tropic of Capricorn is known as Torrid Zone. This area receives the maximum heat as sun is exactly overhead at least once a year.

Ø Temperate Zones.                          

§  The areas between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere and the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere have moderate temperatures. Therefore these areas are called Temperate Zones.       

HEAT ZONES OF THE EARTH

                   

Ø Frigid Zones

§  Areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere, are very cold. It is because here the sun rays are always slanting. Therefore these areas are called Frigid Zones.  

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.