Geography for UPSC: Locations and positions of the Earth

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Geography for UPSC: 

Geography a very wide subject but still good scoring.

Geography needs conceptual clarity so by matching your needs of the different exams from UPSC to SSC and other competitive exams this very article named as Geography for UPSC will help candidates.

You must see-UPSC TOPPERS GEOGRAPHY QUICK REVISION NOTES

Location on Earth

Latitude: Angle subtended by a point to the equatorial place. Lines of latitudes are called parallels.

Longitude: Distance east or west of the meridian of Greenwich.

Equator: Parallel of zero is called equator. It is the largest circle that can be drawn on earth.

Countries on Equator: (countries) Sao Tome and Principe, Gabon, Republic of Congo, Democratic Republic of Congo, Ecuador, Columbia, Brazil, Uganda, Kenya. Somalia, Indonesia. (water bodies) Atlantic Ocean, Gulf of Guinea, Indian Ocean, Gulf of Tomini, Halmahera Sea, Pacific Ocean.

Geographical Mile: One arc of the equator.

Tropic of Cancer: 23.5 degree North.

Countries on Tropic of Cancer: (countries)Mexico, Bahamas, Western Sahara, Mauritania, Mali, Algeria, Niger, Libya, Egypt, Saudi Arabia, UAE, Oman, India, Bangladesh, Myanmar, China, Vietnam, Taiwan; (water bodies) Red Sea, Arabian Sea, Indian Ocean, Taiwan Strait, Pacific Ocean, Gulf of California, Gulf of Mexico, Atlantic Ocean

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Tropic of Capricorn: 23.5 degree South

Countries on Tropic of Capricorn: (countries) Chile, Argentina, Paraguay, Brazil, Namibia, Botswana, South Africa, Mozambique, Madagascar, Australia; (water bodies) Indian Ocean, Atlantic Ocean, Pacific Ocean

Arctic Circle: 66.5 degree North

Areas on Arctic Circle: (countries) Norway, Sweden, Finland, Russia, US-Alaska, Canada, Greenland, Iceland; (water bodies) Arctic ocean, White Sea, Kandalaksha Gulf, Gulf of Ob, Chukchi Sea, Kotzebue Sound, Norwegian Sea, Davis Strait, Greenland Sea.

Antarctic Circle: 66.5 degree South

Areas on Antarctic Circle: (land) Different regains on Antarctica are claimed by some countries – By this claim the circle passes through territories in Antarctica claimed by Australia, France, Argentina, Chile and United Kingdom; (water) Southern Ocean

The two tropics mark the limit of the zones at between which sun’s rays can be vertical at one time of the other. At tropics, sun rays are vertical once a year while in between the tropics twice a year.

  • Summer Solstice: Sun overhead Tropic of Cancer  (June 21) Tropic of Cancer receives vertical rays of the sun. North Pole experiences a continuous day while South Pole experiences a continuous night. Longest day in northern hemisphere.

You must see- Agro climatic regions of India

  • Winter Solstice: Sun overhead Tropic of Capricorn.(December 22)Tropic of Capricorn receives vertical rays of the sun. South Pole experiences a continuous day while North Pole experiences a continuous night. Longest day in the southern hemisphere.
  • Greenwich: Prime meridian
  • Great circle: It is the largest circle that can be drawn on earth. Its plane passes through the centre of the earth. Navigators follow the great circle routes to minimize distance.

Motion of the Earth & Effect of inclination

Earth’s axis is inclined at 23.5 degree from the line perpendicular to the plane of ecliptic (the plane of orbit of the earth around the sun)

Change of season occurs due to a combined effect of the revolution of the earth around the sun and the inclination of its axis. If the axis was not inclined there would have been no change in the amount of energy received by a place throughout the year and hence no change of season. Also, day and night would have been equal in length.

Positions of earth:

 

Equinoxes: (23rd September and 21st March) Equator receives vertical rays of the sun. Day and night are of equal length throughout the world on these days.

The season in the two hemispheres are reverse of each other

At the equator, the days and nights are exactly equal all the year round. Longer than 24 hours day and night are experienced only in the arctic and Antarctic circles.

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Time

  • Time is reckoned with respect to the position of the sun.
  • Time of all places on a given meridian is the same.
  • Time required for one degree rotation is four minutes.

International Date line:

The line at 180 degree distance from the prime meridian is called the International Date line. Moving from the west to east one loses a day if he crosses the line.

The date in the Eastern Hemisphere is ahead that in the western hemisphere. The date line is bent and altered to keep some countries in the same time zone.

The central meridian for India is the longitude of 82.3 degree E which passes near Allahabad. Indian Standard Time is the time of this meridian. It is 5 hrs 30 minutes ahead of the GMT.

  • Solar Day: Average time period required for the successive passages of the sun over a given meridian. It is 24 hours
  • Sidereal day: Time required for a given star in the sky to return to the same position with respect to the earth. It is four minutes less than the solar day. This difference between solar and sidereal day exists because the position of earth with respect to sun keeps changing due to revolution. However, the position with respect a star at infinity is constant.

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  • Solar year: measured with respect to the sun
  • Sidereal year: measured with respect to a star
  • Leap year: Since earth takes slightly more than 365 days for revolution around the sun, one day is added every four years to the calendar. This correction is however too large because the actual solar year is 365.2419 days and not 365.25 days. Hence, the leap year is omitted in the century year unless the century year is divisible by 400 (a leap century). Hence, 1900 was not a leap year but 2000 was.
  • Gregorian Calendar: Julius Ceaser. Pope Gregory XII.

Thank you and all the best

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