NCERT Class 6 - Social Science - Geography
Chapter 2 - GLOBE: LATITUDES AND LONGITUDES
Table of Contents
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GLOBE
- Globe is a true model (miniature form) of the Earth.
- On the globe, countries, continents, and oceans are shown in their correct size.
- An Imaginary line running on the globe divides it into two equal parts. This line is known as the equator.
- The northern half of the earth is known as the Northern Hemisphere and the southern half is known as the Southern Hemisphere.
- The Equator is a very important reference point to locate places on the Earth.
- All parallel circles from the equator up to the poles are called parallels of latitudes. Latitudes are measured in degrees.
- The equator represents the zero-degree latitude.
- Distance from the equator to either of the poles is one-fourth of a circle around the earth, it will measure ¼th of 360 degrees, i.e. 90°.
LATITUDES
- The equator (0°)
- The North Pole (90°N)
- The South Pole (90°S)
- Tropic of Cancer (23½° N) in the Northern Hemisphere.
- Tropic of Capricorn (23½° S) in the Southern Hemisphere.
- Arctic Circle at 66½° north of the equator.
- Antarctic Circle at 66½° south of the equator.
HEAT ZONES OF THE EARTH
- The area between the Tropic of Cancer and the Tropic of Capricorn receives the maximum heat and is called the Torrid Zone.
- 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. These are, therefore, called Temperate Zones.
- Areas 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. Therefore, called Frigid Zones.
LONGITUDES
- Longitudes are the lines of reference running from the North Pole to the South Pole. those are called the meridians of longitude.
- Distances between Longitudes are measured in "degrees". Each degree is further divided into minutes, and minutes into seconds.
- These are semi-circles and the distance between them decreases steadily until it becomes zero at the poles, where all the meridians meet. All meridians are of equal length.
- Meridian's count should begin from the meridian which passed through Greenwich. This meridian is called the Prime Meridian. Its value is 0° longitude.
LONGITUDE AND TIME
- When the Prime Meridian has the sun at the highest point in the sky, all the places along this meridian will have midday.
- 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.
- Eg:
- The time at 15° east of Greenwich :
- The earth rotates 360° in about 24 hours.
- which means 15° = 1 hour.
- => 1° = four minutes.
- When the time 12 noon at Greenwich.
- 15° east of Greenwich = 15 × 4 = 60 minutes.
- Therefore time at 15° east of Greenwich = 1 p.m. and
- Time at 15° west of Greenwich = 11.00 a.m.
STANDARD TIME
- In India, for instance, there will be a difference of about 1 hour and 45 minutes between the local times of Dwarka in Gujarat and Dibrugarh in Assam.
- So, necessary to adopt the standard time for the country.
- In India, the longitude of 82½° E (82° 30'E) is treated as the standard meridian, and time at this meridian is known as the Indian Standard Time (IST).
- India located east of Greenwich at 82°30'E is 5 hours and 30 minutes ahead of GMT.
- The earth has been divided into twenty-four time zones, and Russia has many time zones, which are eleven standard time zones.
