CBSE Class 6 Geo Ch 2: Globes & Coordinates

Chapter Summary

The Earth's Shape: Our Earth is not a perfect sphere. It is slightly flattened at the North and South Poles and bulges in the middle. This shape is described as a 'geoid'.
What is a Globe? A globe is a true model (miniature form) of the Earth. It shows the Earth's features like continents, oceans, and countries in their correct size and location.
Axis: A needle is fixed through the globe in a tilted manner, which is called its axis. This is an imaginary line. The Earth rotates on its own axis.
Poles: The two points on the globe through which the needle passes are the North Pole and the South Pole.
Equator: Another imaginary line running on the globe divides it into two equal parts. This line is known as the Equator. It represents 0° latitude.
Hemispheres: The northern half of the Earth is known as the Northern Hemisphere and the southern half is known as the Southern Hemisphere. Both are equal halves.
Parallels of Latitudes: All parallel circles from the Equator up to the Poles are called parallels of latitudes. Latitudes are measured in degrees (°).
- The Equator is 0° latitude.
- The North Pole is 90° North (90° N) latitude.
- The South Pole is 90° South (90° S) latitude.
- As we move away from the Equator, the size of the parallels of latitude decreases.
Important Parallels of Latitudes:
- Tropic of Cancer: 23½° North of the Equator.
- Tropic of Capricorn: 23½° South of the Equator.
- Arctic Circle: 66½° North of the Equator.
- Antarctic Circle: 66½° South of the Equator.
Heat Zones of the Earth: The tilt of the Earth's axis causes different parts of the Earth to receive varying amounts of sunlight, leading to distinct heat zones.
- Torrid Zone: Lies between the Tropic of Cancer and the Tropic of Capricorn. This zone receives the maximum amount of heat as the mid-day sun is directly overhead at least once a year.
- Temperate Zones: Lies 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. These zones have moderate temperatures because the mid-day sun is never directly overhead.
- Frigid Zones: Lies between the Arctic Circle and the North Pole in the Northern Hemisphere, and the Antarctic Circle and the South Pole in the Southern Hemisphere. These zones are very cold because the sun's rays are always slanting and provide less heat.
Meridians of Longitude: These are imaginary lines that run from the North Pole to the South Pole. They are semi-circles.
- The distance between them decreases steadily polewards until it becomes zero at the poles.
- Unlike parallels of latitude, all meridians are of equal length.
Prime Meridian: To number the meridians, a reference line is needed. The meridian passing through Greenwich, where the British Royal Observatory is located, was chosen as the Prime Meridian. Its value is 0° longitude.
Eastern and Western Hemispheres: The Prime Meridian divides the Earth into two equal halves, the Eastern Hemisphere and the Western Hemisphere, extending up to 180° East and 180° West longitudes respectively.
Grid: The network of parallels of latitude and meridians of longitude forms a grid on the globe. This grid is used to locate any point on the Earth accurately.
Longitude and Time:
- The Earth rotates from west to east. Places east of Greenwich are ahead of GMT (Greenwich Mean Time), and those to the west are behind it.
- The Earth takes 24 hours to complete one rotation (360°). This means it rotates 15° in an hour or 1° in 4 minutes.
- Indian Standard Time (IST): India is located east of Greenwich at 82½° E longitude. The time at this meridian is taken as the standard time for the whole country. IST is 5 hours and 30 minutes ahead of GMT. This means that if it is 12 noon at Greenwich, it will be 5:30 p.m. in India.

Questions and Answers

1. Answer the following questions briefly.

(a) What is the true shape of the Earth?

Answer: The true shape of the Earth is a 'geoid', which means it is not a perfect sphere. It is slightly flattened at the North and South Poles and bulges in the middle.

(b) What is a globe?

Answer: A globe is a true miniature model of the Earth. It shows the Earth's features like continents, oceans, and countries in their correct relative size and location.

Answer: The latitudinal value of the Tropic of Cancer is 23½° North (23.5° N).

(d) What are the three heat zones of the Earth?

Answer: The three heat zones of the Earth are:

Torrid Zone
Temperate Zones (Northern and Southern)
Frigid Zones (Northern and Southern)

(e) What are parallels of latitude and meridians of longitude?

Answer:

Parallels of Latitude: These are imaginary full circles parallel to the Equator, running from east to west. They measure the distance north or south of the Equator. Their size decreases as they move from the Equator towards the poles.
Meridians of Longitude: These are imaginary semi-circles running from the North Pole to the South Pole, from north to south. They measure the distance east or west of the Prime Meridian. All meridians are of equal length.

(f) Why does the Torrid Zone receive maximum amount of heat?

Answer: The Torrid Zone receives the maximum amount of heat because the mid-day sun is directly overhead at least once a year in this area, which lies between the Tropic of Cancer and the Tropic of Capricorn. The sun's rays fall almost vertically here.

(g) Why is it 5:30 p.m. in India and 12:00 noon in London?

Answer: London is located on the Prime Meridian (0° longitude). India is located to the east of Greenwich at 82½° E longitude. The Earth rotates from west to east. For every 15° longitude, there is a time difference of 1 hour.
The difference in longitude between India (82.5° E) and London (0°) is 82.5°.
Time difference = 82.5° × 4 minutes/degree = 330 minutes.
330 minutes = 5 hours and 30 minutes.
Since India is to the east, its time is ahead of London's time. Therefore, when it is 12:00 noon in London, it is 5:30 p.m. in India.

2. Tick the correct answer.

(a) The Tropic of Capricorn is located at

(i) 23½° N
(ii) 23½° S
(iii) 66½° N

Answer: (ii) 23½° S

(b) The Arctic Circle is located at

(i) 66½° S
(ii) 23½° N
(iii) 66½° N

Answer: (iii) 66½° N

(i) 180
(ii) 360
(iii) 90

Answer: (ii) 360

(d) The South Pole is located at

(i) 90° N
(ii) 90° S
(iii) 0°

Answer: (ii) 90° S

(e) The grid is a network of

(i) parallels of latitudes and the meridians of longitudes
(ii) the Tropic of Cancer and the Tropic of Capricorn
(iii) the North Pole and the South Pole

Answer: (i) parallels of latitudes and the meridians of longitudes

3. Fill in the blanks.

(a) The Tropic of Cancer is located at __________.

Answer: The Tropic of Cancer is located at 23½° N latitude.

(b) The Standard Meridian of India is __________.

Answer: The Standard Meridian of India is 82½° E longitude.

Answer: The 0° Meridian is also known as the Prime Meridian.

(d) The distance between the longitudes _________ towards the poles.

Answer: The distance between the longitudes decreases towards the poles.

(e) The Arctic Circle is located in the __________ hemisphere.

Answer: The Arctic Circle is located in the Northern hemisphere.

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