The latitude of a pole is considered to be the distance of a place from north and south of the equator. This is measured as an angle. If all places having the same latitudes are joined by a straight line which will run with equator 0o. They are used to join two poles namely, north and south. Their length may vary but their distance remains constant some of the important latitude and longitude are: –
|1||Tropic of Cancer||23½o North|
|2||Tropic of Capricorn||23½o South|
|3||Arctic Circle||66½o North|
|4||Antarctic Circle||66½o South|
There are various zones — the parallels a mentioned under: –
- Tropical zones – Between tropic of cancer and tropic of Capricorn. Here lies the hot area.
- Temperature zone – This zone lies between the 66½o to 90o (near about in both the hemisphere). This area is a cold area.
- Frigid Zone – This zone lies between 66½o to 90o both in northern and southern hemisphere. This area is said to be very cold one.
- Longitude – The longitude is used to show the distance of a point from east or west of two prime meridian which at 0o and passes through Greenwich near London. Here, an observatory is placed to measure the 0o time difference. There are 360o longitude and these join pole to pole. These lines of longitude are called meridians. The longitude is measured from 0o to 180o degree. These move towards either in the east or in the west direction. The west longitude is termed positive and the east longitude is considered to be negative. Since the earth completes one rotation on its axis in 24 hours. Therefore, the time gap of one degree longitude rotation is four minutes. As per general rule, places on eastwards sides due to reference point have a time ahead. This also observes the lagging behind of time on westward side.
Standard time: – it refers to the time zone of an area like a country or town. This is time of a meridian which is centrally located. Furthermore, it refers to the same time which is given to a place or whole area or a country. The region assigned to the whole area is known as time zone. These time zones differ on the basis of division of Greenwich Mean Time. India is situated on the longitude of 82o 30o east. This longitude passes through Naini, Allahabad. This local meridian sets the Indian standard time. The standard time of India is about 5½ hours ahead of Greenwich Mean Time. This is somewhat halfway around the globe from Greenwich meridian. This is because 1800 longitude is said to be international date time. This is an imaginary line following the 180th meridian. If a person was crossed this imaginary line from the direction of east towards west, he will gain one day and vice versa.
Dava Sobel in his book, “Longitude : The true story of a Lone Genius who solved the Greatest Scientific Problem of his Time” observes, “one degree of longitude equals four minutes of time the world over, but in terms of distance, one degree shrinks from sixty-eight miles at the equator to virtually nothing at the poles.