Class 6th Ncert Geography Notes ch -2 -Latitudes and Longitudes

Class 6th Ncert Geography Notes ch -2 -Latitudes and Longitudes

Class 6th Ncert Geography Notes ch -2 -Latitudes and Longitudes

  • There are two poles on Earth – One is North Pole And Another is South Pole.
  • An imaginary  line running on the globe divides it into two equal parts.
  • This line is known as the equator.
  • The northern half of the earth is known as the Northern Hemisphere and the southern half is known as theSouthern Hemisphere.
  • They are both equal halves.
  • Therefore, the equator is an imaginary circular line and is a very important reference point to locate places on the earth.
  • All parallel circles from the equator up to the poles are called parallels of latitudes.
  • Latitudes are measured in degrees.
  • The equator represents the zero degree latitude.
  • Since the distance from the equator to either of the poles is one-fourth of a circle round the earth, it will measure ¼th of 360 degrees, i.e. 90°.
  • Thus, 90 degrees north latitude marks the North Pole and 90 degrees south latitude marks
    the South Pole.
  • As such, all parallels north of the equator are called ‘north latitudes.’
  • Similarly all parallels south of the equator are called ‘south latitudes.’
  • The value of each latitude is, therefore, followed by either the word north or south.
  • Generally, this is indicated by the letter ‘N’ or ‘S’. For example, both Chandrapur in Maharashtra (India) and Belo Horizonte in Brazil (South America) are located on parallels of about 20° latitude.
  • But the former is 20° north of the equator and the latter is 20° south of it.
  • We, therefore, say that Chandrapur is situated at 20° N latitude and Belo Horizonte is situated at 20° S latitude.
  • that as we move away from the equator, the size of the parallels of latitude decreases.

IMPORTANT PARALLELS OF LATITUDES

  • Besides the equator (0°), the North Pole (90°N) and the South Pole (90° S),
  • there are four important parallels of latitudes–
    (i) Tropic of Cancer (23½° N) in the  Northern Hemisphere.
  • (ii) Tropic of Capricorn (23½° S) in the Southern Hemisphere.
  • (iii) Arctic Circle at 66½° north of the equator.
  • (iv) Antarctic Circle at 66½° south of the equator.

HEAT ZONES OF THE EARTH

  • The mid-day sun is exactly overhead at least once a year on all latitudes in between the Tropic of Cancer and the Tropic of Capricorn.
  • This area, therefore, receives the maximum heat and is called the Torrid Zone.
  • The mid-day sun never shines overhead on any latitude beyond the Tropic of Cancer and the Tropic of Capricorn.
  • The angle of the sun’s rays goes on decreasing towards the poles.
  • As such, the areas bounded by the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere, and the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere, have moderate  temperatures.
  • These are, therefore, called Temperate Zones.
  • Areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere, are very cold.
  • It is because here the sun does not rise much above the horizon.
  • Therefore, its rays are always slanting. These are, therefore, called Frigid Zones.

 WHAT ARE LONGITUDES?

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  • To fix the position of a place, it is necessary to know something more than the latitude of that place.
  • You can see, for example, that Hyderabad (in Pakistan) and Allahabad (in India) are situated on the same latitude (i.e., 25°25’N).
  • Now, in order to locate them precisely, we must find out how far east or west these places are from a given line of reference running from the North Pole to the South Pole.
  • These lines of references are called the meridians of longitude, and the distances between them are measured in ‘degrees of longitude.’
  • Each degree is further divided into minutes, and minutes into seconds.
  • They are semi-circles and the distance between them decreases steadily polewards until it becomes zero at the poles, where all the meridians meet.
  • Unlike parallels of latitude, all meridians are of equal length.
  • Thus, it was difficult to number the meridians.
  • Hence, all countries decided that the count should begin from the meridian which passed through Greenwich, where the British Royal Observatory is located.
  • This meridian is called the Prime Meridian.
  • Its value is 0° longitude and from it we count 180° eastward as well as 180° westward.
  • The Prime Meridian divides the earth into two equal halves, the Eastern Hemisphere and theWestern Hemisphere.
  • Therefore, the longitude of a place is followed by the letter E for the east and W for the west.
  • It is, however, interesting to note that 180° East and 180° West meridians are on the same line.

LONGITUDE AND TIME

  • The best means of measuring time is by the movement of the earth, the moon and the planets.
  • The sun regularly rises and sets every day, and naturally, it is the best time-keeper throughout the world.
  • Local time can be reckoned by the shadow cast by the sun, which is the shortest at noon and longest at sunrise and sunset.
  • When the Prime Meridian of Greenwich has the sun at the highest point in the sky, all the places along this meridian will have mid-day or noon.
  • As the earth rotates from west to east, those places east of Greenwich will be ahead of Greenwich time and those to the west will be behind it .
  • The rate of difference can be calculated as follows. The earth rotates 360° in about 24 hours, which means 15° an hour or 1° in four minutes. Thus, when it is 12 noon at Greenwich, the time at 15° east of Greenwich will be 15 × 4 = 60 minutes, i.e., 1 hour ahead of Greenwich
    time, which means 1 p.m. But at 15° west of Greenwich, the time will be behind Greenwich time by one hour, i.e., it will be 11.00 a.m.
  • Similarly, at 180°, it will be midnight when it is 12 noon at Greenwich.
  • At any place a watch can be adjusted to read 12 o’clock when the sun is at the highest point in the sky, i.e., when it is mid-day.
  • The time shown by such a watch will give the local time for that place.
  • You can see that all the places on a given meridian of longitude have the same local time.

 

(a) The value of the prime meridian is
(i) 90° (ii) 0° (iii) 60°

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(b) The frigid zone lies near
(i) the Poles (ii) the Equator (iii) the Tropic of Cancer

(c) The total number of longitudes are
(i) 360 (ii) 180 (iii) 90

(d) The Antarctic circle is located in
(i) the Northern hemisphere
(ii) the Southern hemisphere
(iii) the Eastern hemisphere

(e) Grid is a network of
(i) parallels of latitudes and merdians of longitudes
(ii) the Tropic of Cancer and the Tropic of Capricorn
(iii) the North Pole and the South Pole