NCERT 6th Class (CBSE) Social Science: Globe: Latitudes and Longitudes

Question: What are heat zones of earth?

Answer: On the basis of the distance from the equator, the earth is divided into the following heat/temperature zone:

1. Torrid Zone: ‘Torrid’ means hot. The Torrid Zone lies between the tropic of cancer and the tropic of Capricorn. Since the direct rays of the sun fall throughout the year in this zone.
2. Temperate Zone: ‘Temperate’ means moderate. The North Temperate Zone lies between the tropic of Cancer ( 23 1/2° N ) and the Arctic (66 1/2° N ) and the South Temperate Zone. (23 1/2° S) and the Antarctic Circle (66 1/2° S ). These areas experience moderate temperature as they receive slanting rays of the sun.
3. Frigid Zone: ‘Frigid’ means cold. The North Frigid Zone lies between the Arctic Circle (66 1/2° N) and the North pole and the South Frigid Zone lies between the Antarctic Circle (66 1/2° S) and the South pole. The sun rays are very slanting and therefore there is very little heating in there zones.

Diagram: Temperature Zone.

Question: Explain how time and date change when one crosses the IDL.

Answer: Time and date change as:

1. The 180° longitude is important because the international Date Line runs along It. Day and date change at the IDL.
2. Crossing the IDL from east to west a traveler will add or gain a day. While crossing it from west to east he will subtract or lose a day.

Question: How is local time determined?

Answer: Longitude helps us to determine the time at a place. The earth rotates from west to east or in an anti-clockwise direction. Therefore all places to the east of a particular meridian will have sunrise earlier and all places in the west will have it later. It takes 24 hours to complete one rotation of 360°. This means that the earth spins 15° (360/24) in one hour or 1° in 4 minutes. Therefore, a place 1° east of another place will have sunrise 4 minutes earlier. Thus, each longitude has its own time which is called the local time of that longitude.