Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
The Globe
A globe is a small, round, true model of the Earth. The Earth itself is slightly flattened at the poles, but on a globe it is shown as a perfect sphere so that shapes, sizes and directions can be seen correctly. A globe can be rotated just like the Earth.
Latitudes (Parallels)
Latitudes are imaginary horizontal lines that run east to west and are parallel to each other and to the Equator. That is why they are also called parallels of latitude.
- The Equator is the 0° latitude, the largest circle around the Earth.
- Latitudes are measured in degrees (°), from 0° at the Equator to 90° at the poles.
- All latitudes are circles, but they get smaller as we move towards the poles.
Important Parallels of Latitude
| Latitude | Name |
|---|---|
| 0° | Equator |
| 23½° N | Tropic of Cancer |
| 23½° S | Tropic of Capricorn |
| 66½° N | Arctic Circle |
| 66½° S | Antarctic Circle |
| 90° N | North Pole |
| 90° S | South Pole |
The Equator divides the Earth into the Northern Hemisphere and the Southern Hemisphere.
Heat Zones of the Earth
The Earth is divided into three heat zones based on the amount of heat received from the Sun:
| Zone | Location | Heat received |
|---|---|---|
| Torrid Zone | Between the Tropic of Cancer and the Tropic of Capricorn | Maximum — the Sun is almost overhead all year |
| Temperate Zones | Between each Tropic and its Polar Circle (North and South) | Moderate |
| Frigid Zones | Between each Polar Circle and its pole (North and South) | Very little — the Sun's rays are very slanted |
Longitudes (Meridians)
Longitudes are imaginary lines that run from the North Pole to the South Pole. They are also called meridians of longitude.
- The Prime Meridian is the 0° longitude; it passes through Greenwich (London, UK).
- Longitudes are measured in degrees east (E) and west (W) of the Prime Meridian, up to 180°.
- The Prime Meridian divides the Earth into the Eastern Hemisphere and the Western Hemisphere.
- The 180° meridian and the Prime Meridian together form a circle; the International Date Line (IDL) lies roughly along the 180° meridian.
Longitudes and Time
- The Earth rotates 360° in 24 hours, so it turns 1° in 4 minutes.
- This means places on different longitudes have different local times.
- To avoid confusion, each country chooses a standard meridian as the basis of one uniform standard time.
Indian Standard Time (IST)
- India's standard meridian is 82½° E.
- IST is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT), written as IST = GMT + 5:30.
Location of India
- Latitudes: 8°4′ N to 37°6′ N
- Longitudes: 68°7′ E to 97°25′ E
- The Tropic of Cancer (23½° N) passes through the middle of India, so India lies partly in the Torrid Zone and partly in the Temperate Zone.
Key Vocabulary
| Term | Meaning |
|---|---|
| Globe | A true miniature model of the Earth |
| Latitude | An east-west line parallel to the Equator |
| Longitude | A north-south line from pole to pole |
| Equator | 0° latitude; divides Earth into two hemispheres |
| Prime Meridian | 0° longitude; passes through Greenwich |
| Hemisphere | Half of the Earth |
| Standard meridian | The longitude used to fix a country's standard time |
Exam Tips
- Remember the two Tropics are at 23½° and the two Polar Circles at 66½° — these four values are commonly asked.
- The three heat zones (Torrid, Temperate, Frigid) and where each lies is a favourite 2-mark question — draw the simple globe diagram.
- 1° longitude = 4 minutes of time difference is the key fact for time-zone questions.
- India's standard meridian is 82½° E and IST = GMT + 5:30 — a very common 1-mark question.
- The Equator is a latitude; the Prime Meridian is a longitude — do not mix them up.