Class Notes NCERT Solutions for CBSE Students
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:
- 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.
- 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.
- 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:
- The 180° longitude is important because the international Date Line runs along It. Day and date change at the IDL.
- 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.
