CHAPTER- 2 GLOBE: LATITUDES AND LONGITUDES
Notes
1. Our Earth is not perfectly spherical. It is slightly flattened at the North and South Poles and slightly bulging in the middle (at the equator).
2. Globe – A globe is a real model of the Earth in a small form.
- Globes can be of different sizes and types—large globes, small pocket-sized globes, and balloon-like globes.
- On a globe, countries, continents, and oceans are shown in their correct shapes.
- A needle is placed in a tilted position inside the globe, which is called the axis.
- The two points on the globe through which the needle passes are the North Pole and the South Pole.
- Another imaginary line also divides the globe into two equal parts; this is called the Equator.
- The half of the Earth located in the north is called the Northern Hemisphere, and the half located in the south is called the Southern Hemisphere.
- All the parallel circles from the Equator to the poles are called latitudes (parallels).
3. Important lines of latitude —
- Equator (0°), North Pole (90° N), and South Pole (90° S).
- 1. Tropic of Cancer (23°30′ N) in the Northern Hemisphere. 2. Tropic of Capricorn (23°30′ S) in the Southern Hemisphere. 3. Arctic Circle at 66°30′ north of the Equator. 4. Antarctic Circle at 66°30′ south of the Equator.
4. Torrid Zone – In all the latitudes between the Tropic of Cancer and the Tropic of Capricorn, the Sun is directly overhead at noon at least once a year. Therefore, this region receives the maximum heat and is called the Torrid Zone.
5. Temperate Zone – The regions between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere, and between the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere have a moderate temperature. Therefore, these regions are called the Temperate Zones.
6. Frigid Zone – The regions between the Arctic Circle and the North Pole in the Northern Hemisphere and between the Antarctic Circle and the South Pole in the Southern Hemisphere are very cold. This is because the Sun does not rise very high above the horizon there. Therefore, these regions are called the Frigid Zones.
7. Longitude – The reference lines that measure the distance of places to the east or west from a reference line joining the North Pole and the South Pole are called longitudes (meridians).
8. All countries decided that counting to the east and west would begin from the meridian passing through Greenwich, where the British Royal Observatory is located. This meridian is called the Prime Meridian.
- Its value is 0° longitude.
9. The best way to measure time is by the movement of the Earth, the Moon, and the planets.
- The Earth rotates 360° on its axis in about 24 hours. This means it rotates 15° in 1 hour and 1° in 4 minutes.
- When the Sun reaches its highest point in the sky at any place, it is 12 noon there. Thus, the time shown by the clock at that place is called its local time.
10. In India, 82°30′ East longitude is considered the Standard Meridian. The local time of this meridian is taken as the standard time for the whole country. It is known as Indian Standard Time (IST).
EXERCISES
Question- 1. Answer the following questions briefly.
(a) What is the true shape of the earth?
Answer- Our Earth is not perfectly spherical. It is slightly flattened at the North and South Poles and slightly bulging in the middle (at the equator).
(b) What is a globe?
Answer- A globe is a real model of the Earth in a small form.
(c) What is the latitudinal value of the Tropic of cancer?
Answer- The latitudinal value of the Tropic of Cancer is 23°30′.
(d) What are the three heat zones of the Earth?
Answer- The Earth has three heat zones:
1. Torrid Zone, 2. Temperate Zone, 3. Frigid Zone.
(e) What are parallels of latitude and meridians of longitude?
Answer- All the parallel circles from the Equator to the poles are called lines of latitude.
The lines that join or connect the North Pole and the South Pole are called lines of longitude.
(f) Why does the torrid zone receive maximum amount of head?
Answer- At all the latitudes between the Tropic of Cancer and the Tropic of Capricorn, the Sun is directly overhead at noon at least once a year. Therefore, this region receives the maximum heat.
(g) Why is it 5.30 p.m. in India and 12.00 noon in London?
Answer- Since the Earth rotates from west to east, the places that are east of Greenwich are ahead of Greenwich time, and the places that are west of Greenwich are behind it. London is located at 0° longitude, while India’s Standard Time is set at 82°30′ East longitude.
The value of 1° equals 4 minutes, so 82°30′ equals 5 hours 30 minutes. Therefore, when it is 12:00 noon in London, it is 5:30 PM in India.
Question- 2. Tick the correct answers.
(a) The value of the prime meridian is
(1) 90° (2) 0° (3) 60°
(b) The frigid zone lies near
(1) The poles (2) the Equator (3) the tropic of cancer
(c) The total number of longitudes are
(1) 360 (2) 180 (3) 90
(d) The Antarctic circle is located in
(1) The Northern hemisphere
(2) The Southern hemisphere
(3) The Eastern hemisphere
(e) Grid is a network of
(1) Parallels of latitudes and meridians of longitudes
(2) The tropic of cancer and the tropic of Capricorn
(3) The north pole and the south pole
Answer- (a)- (2) 0°, (b)- (1) the poles, (c)- (1) 360, (d)- (2) the Southern hemisphere, (e)- (1) parallels of latitudes and meridians of longitudes.
Question- 3. Fill in the blanks.
(a) The tropic of Capricorn is located at _________.
(b) The standard meridian of India is __________.
(c) The 0° meridian is also known as __________.
(d) The distance between the longitudes decreases towards ___________.
(e) The Arctic Circle is located in the ____________ hemisphere.
Answer- (a) The tropic of Capricorn is located at 23°30' South.
(b) The standard meridian of India is 82°30'.
(c) The 0° meridian is also known as Prime Meridian.
(d) The distance between the longitudes decreases towards Poles.
(e) The Arctic Circle is located in the Northern hemisphere.