Chapter 1 – Locating Places on Earth

Chapter 1 – Locating Places on Earth

 

1. Globe

•  The globe  is a true model of the earth.
• It helps us to understand the position of the shape of the earth, continents, oceans, and countries.
• Globes can be of different sizes and types – some large and some small, some pocket-sized.
• We can rotate the globe in the same way that a potter’s wheel or top spins.

2. Axis

• A needle is placed in an inclined position on the globe, which  is called  the axis.
• It is an  imaginary line around which the earth revolves.
•  The North Pole and the South Pole are the two points through which the axis passes.
• The Earth does not actually tilt, it is only shown as a model on the globe.

3. Equator

• In addition to the axis, there is another imaginary line on the globe that divides the globe into two equal halves. This is  called the  equator.
• The equator is an important reference point on Earth.
• The north half of the equator  is called  the Northern Hemisphere and the southern half  is called the  Southern Hemisphere.
• These two are equal halves.

4. Latitudes

• All parallel circles from the equator to the poles  are called  parallels of latitudes.
• These  are measured in degrees.
• The latitude of the equator is  0°.
•  The   value of latitude increases as we move from the equator towards the poles.
• The North Pole is at 90° North latitude, and  the South Pole is at  90° South latitude.
• Important Parallels of Latitudes:
  • Tropic of Cancer: 23.5° North latitude (in the Northern Hemisphere)
  •  Tropic of Capricorn: 23.5° South latitude (in the Southern Hemisphere)
  •  Arctic Circle: 66.5° North latitude (near the North Pole)
  •  Antarctic Circle: 66.5° south latitude (near the South Pole)

5. Heat Zones

Latitude lines define the different  heat zones  on Earth:

1. Torrid Zone:

• • This is  the area between the Tropic of Cancer and the Tropic of Capricorn.
  • In this region, the sun’s rays fall right above the head at least once a year, which  provides maximum heat  here.
  • It is the warmest tropic.

1. Temperate Zones:

• • Northern Temperate: The region between the Tropic of Cancer and the Arctic Circle.
  • Southern Temperate: The area between the Tropic of Capricorn and the Antarctic Circle.
  • In these areas, the sun’s rays never fall directly on the head.
  • The temperature here  is moderate.

iii.  Frigid Zones:

• • Northern Cold Zone: The region between the Arctic Circle and the North Pole.
  • Southern Cold Zone: The region between the Antarctic Circle and the South Pole.
  • Here the sun’s rays fall very obliquely and do not rise above the horizon, so  it is very cold  here.

 

 

6. Longitudes

• In addition to the lines of latitude,  meridians of longitude  are required to accurately locate locations on Earth.
• These are semi-circular lines connecting the North Pole with the South Pole.
• All longitudes have the same length.
•  Prime Meridian:
  • It is 0° longitude, passing through the Royal Observatory located in Greenwich, near London.
  • It is  also known as Greenwich Meridian.
  • It divides the Earth into the  Eastern Hemisphere and the Western Hemisphere.

 

7. Grid

• When latitude lines and longitude lines intersect each other, they form a  grid.
• Using this grid we can accurately locate any place on Earth.
• To tell the position of any place, we should know both its latitude and longitude.
• Example: Delhi is located at  28.7° north latitude and 77.2° east longitude.

 

8. Measuring Time and Longitude

• The earth rotates on its axis from west to east.
• It takes  4  minutes for the earth to travel from one longitude to another. (It takes  24 hours to rotate  360° longitude, then 24 hours/hour to rotate 1°.) 360° = 1440 min/min 360° = 4 min).
•  Greenwich Mean Time (GMT):  The time at the prime meridian in Greenwich is called  GMT.
•  Local Time: The local time of a place is determined by the position of the sun at noon.
•  Standard Time:
  • In order to maintain the uniformity of time within a country, the local time of a central longitude is considered as the standard time of the entire country.
  • Standard meridian of India: 82.5° east longitude is considered as the standard meridian of India.
  • This is because the longitude in India is about 30°  , which can cause a difference of about 2 hours in local time.
  •  Indian Standard Time (IST): 82.5° East Longitude Local Time, which is  5 hours and 30  minutes ahead of  GMT.