• Globe is true model [Miniature form] of Earth.
• On globe, Countries, Continents, and Oceans are shown in their correct size.
• A needle is fixed through globe in a tilted manner which is known as its axis.
• Two points on globe through which needle passes known as poles are– North Pole and South Pole.
• globe can be moved around needle from west to east just as Earth moves.
• Equator is an imaginary line running through globe which divides it into two equal parts.
• Equator is a very important reference point to locate places on earth.
• Northern half of Earth is called northern hemisphere and Southern half is called Southern Hemisphere.
• Parallels of latitude: All parallel circles from equator to poles are known as parallels of latitudes which are measured in degree.
• Equator is zero degree latitude and 90 degree north latitude marks Northern Pole and 90 degree latitude marks South Pole.
• Northern latitudes: All latitudes north of equator, are indicated by ‘N’.
• Southern Latitudes: All latitudes south of equator are indicated by ‘S’.
Heat Zones on Earth
• Torrid Zone: latitudes between Tropic of Cancer and Tropic of Capricorn where mid sun is exactly overhead at least once a year known as Torrid Zone. Sun is never overhead beyond these areas.
• Temperate Zones: areas bounded by Tropic of Cancer and Arctic Circle in northern hemisphere and Tropic of Capricorn and Antarctic Circle in southern hemisphere where temperature is moderate; is known as Temperate Zones.
• Frigid Zone: areas lying between Arctic Circle and North Pole in northern hemisphere and Antarctic Circle and South Pole in southern hemisphere are known as frigid zone. This is a very cold area.
Some important Latitudes
• Tropic of Cancer: 23 ½° in northern hemisphere.
• Tropics of Capricorn: 23 ½° in southern hemisphere.
• Arctic Circle: at 66 ½° north of equator.
• Antarctic Circle: at 66 ½° south of equator.
• In order to locate correct position of places, we must know how far east or west these places are located from given line of reference line running from North Pole to South Pole. These lines of reference are known as meridians of longitude.
• Each degree is divided into minutes and minutes divided into seconds.
• distance between two longitudes steadily decreases from equator to pole where all meridians meet.
• All meridians have equal length and are counted from Prime meridian which passes through Greenwich where Royal British Observatory is located.
• prime meridian’s value is zero. From Prime Meridian we measure 180 degrees eastward [E] and 180 degrees westward [W].
Longitude and Time
• Those places east of Greenwich will be ahead of Greenwich time and those to west will be behind Greenwich time.
• Earth rotates 360 degree in 24 hours which means 15 degree in an hour or 1 degree in four minutes.
• Standard Time: This is necessary to adopt local time of some central meridian of a country.
• In India, it is 82° ½ E is treated as standard meridian. local time at this meridian is known as Indian standard time [IST]. France, including its overseas territories, has most time zones .