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Summary
The Earth is like a slightly squashed ball, making it a bit hard to find exact spots on its surface. To find any place, we use a system of imaginary lines. These lines are called latitudes and longitudes, and they are measured in units called degrees. Knowing a place’s location is very helpful. It helps us understand its climate; for instance, places far from the Equator are usually colder. It’s also important for ships and airplanes to find their destinations. Location information is used in business and helps us read maps in an atlas. It can tell us which half of the Earth a place is in, predict sunrise and sunset times, and understand seasons.
Latitude tells us how far north or south a place is from the Equator, an imaginary line around the middle of the Earth. Latitude is an angle measured from the Earth’s center. In the northern part of the world, the Pole Star helps find latitude; the star’s height in the sky is the same as the latitude. A tool called a sextant can also measure angles to the sun or stars. Today, GPS uses satellites for this. Lines of latitude are called parallels. They are circles that run east and west, always parallel to the Equator, which is 0° latitude. Other important parallels include the Tropics and the Arctic and Antarctic Circles. These lines help show Earth’s heat zones: hot near the Equator, cold near the poles, and mild in between. Each degree of latitude is about 111 kilometers apart.
Longitude tells us how far east or west a place is from a special line called the Prime Meridian. This line passes through Greenwich in London and is 0° longitude. Lines of longitude are called meridians. They are semi-circles running from the North Pole to the South Pole. All places on the same meridian have noon at the same time. Unlike parallels of latitude, meridians are not parallel to each other; they meet at the poles.
The Earth rotates 360 degrees in 24 hours, meaning it turns 15 degrees every hour. This rotation is why we have different times around the world. Local time is the specific time at a meridian. To avoid issues with having many different local times, countries often use a Standard Time. This is the local time of a central meridian for the whole region. GMT, or Greenwich Mean Time, is the time at the Prime Meridian. The 180° longitude line is opposite to the Prime Meridian and is important for the International Date Line. This line is where the date changes. It zigzags to keep island groups in the same day. Antipodes are places directly opposite each other on Earth. Their latitudes are the same number but in opposite hemispheres, and their longitudes are 180° apart, also in opposite hemispheres. The time difference between antipodes is 12 hours.
Textual Questions, Answers (Oriental)
Multiple Choice Questions
1. Latitude of Kolkata is 22°34′. Its angular measurement will be
(a) 34°22′
(b) 24°22′
(c) 22°34′
(d) 36°28′
Answer: (c) 22°34′
2. Highest latitude is
(a) 0°
(b) 90°
(c) 180°
(d) 360°
Answer: (b) 90°
3. The difference of local time between Kolkata and Allahabad is
(a) 12 minutes
(b) 18 minutes
(c) 20 minutes
(d) 24 minutes
Answer: (d) 24 minutes
4. The time difference between a place and its antipode is
(a) 6 hours
(b) 12 hours
(c) 16 hours
(d) 24 hours
Answer: (b) 12 hours
5. The total no of parallels of latitude on a globe
(a) 90
(b) 179
(c) 180
(d) 360
Answer: (b) 179
6. The altitude of the polestar at North Pole is
(a) 80°
(b) 90°
(c) 75°
(d) 35°
Answer: (b) 90°
7. Prime Meridian is
(a) 0°
(b) 90°
(c) 180°
(d) 360°
Answer: (a) 0°
8. Time difference at 1° interval of longitude is
(a) 4 minute
(b) 12 minute
(c) 24 minute
(d) 36 minute
Answer: (a) 4 minute
9. The antipode of a place on Prime Meridians is
(a) 0°
(b) 90°
(c) 60°
(d) 180°
Answer: (d) 180°
10. The time difference at two sides of the International dateline is-
(a) 28 hrs
(b) 24 hrs
(c) 12hrs
(d) 0 hrs
Answer: (b) 24 hrs
11. Total meridians of longitude is
(a) 90
(b) 100
(c) 180
(d) 360
Answer: (d) 360
Answer in a few words
1. What angle does each meridian make on Equator ?
Answer: Each meridian cuts the equator at right angle.
2. What is the highest meridian of longitude?
Answer: The highest possible longitude is 180°.
3. How could (by which star) we calculate the latitude in southern hemisphere ?
Answer: In the southern hemisphere a similar fixed star Hadley’s Octant is used to find out a latitude.
4. What is the latitude of Arctic circle ?
Answer: The latitude of Arctic circle is 66½°N.
5. With the intersection of latitude and longitude a rectangular space is created. What is it?
Answer: Earth Grid is made up of some perpendicular lines intersecting north-south and east-west forming a network. With the intersection of latitude and longitude a rectangular space is created, which is part of this Earth Grid.
Fill in the blanks
True or false
Short answer type questions
1. Write the difference between parallels and parallels of latitudes.
Answer: The differences between Parallels of Latitude and Meridians of Longitude are as follows:
| Point of difference | Parallels of Latitude | Meridians of Longitude |
| [A] Orientation | Parallels are extended in east-west direction. | Meridians are extended in north-south direction. |
| [B] Extent | Parallels are extended in east-west direction. | Meridians are extended in north-south direction. |
| [C] Types | They are parallel to each other. | They are not parallel. |
| [D] Highest | The highest possible latitude is 90°. | The highest possible longitude is 180°. |
| [E] Total No. | There are 89 parallels in both the hemisphere at an interval of 1°. The total is 179. | There are 180 meridians in both the hemisphere. The total in 360. |
| [F] Length | From the equator towards the poles the parallels are getting smaller in length. | Meridians remain uniform in length. |
| [G] Climate | Parallels are related to climatic belts. | Meridians are related to local time. |
| [H] Angle | Total angular measurement is 360°. | Total angular measurement is 180. |
2. What are uses of latitudes.
Answer: The uses of latitudes, or the necessity of determination of the location of a place on the earth’s surface which involves knowing latitude, include:
(i) To Know the Concept of Climate: If we know the latitudinal location of a place we can easily derive an idea of the climatic types of the place. For example if the place is at higher latitude i.e 60°-70°N/S then the place must be in colder region. If it is in between 70°-90° latitude, both North and South, then the region must be covered by snow almost all time of the year. Again if the latitudinal region is between 30°-60° (North and South) the temperate climate prevail. In the lower latitudes i.e., between 0°-30° N/S the climate is hot tropical type.
(vi) To locate the hemisphere: Location of a place helps us to generate an idea about the hemisphere.
(vii) Sunset and Sunrise: Exact location of the place helps us to generate an idea about the timing of sunrise and sunset.
(viii) Season length of day and night: It is easier to develop the idea of season, the length of day and night according to date if we know the exact location.
Latitudes also help in the identification of Heat Zones.
3. Divide the world into heat zones depending upon the latitude.
Answer: The world is divided into heat zones depending upon the latitude as follows:
| Latitude | Location | Climate | Temperature |
| 0-23½° | lower lati. | Torrid | hot |
| 23½°-66½° | Middle lati. | Temperate zone | mild |
| 66½°-90° | Higher lati. | Frigid | Cold. |
This can be visualized with the N. Hemisphere having the Arctic Circle, N. Temperate Zone, and Tropic of Cancer, and the S. Hemisphere having the Antarctic Circle, S. Temperate Zone, and Tropic of Capricorn, with the Equator in the middle.
[This answer needs diagram present on Page number 4, Fig. 3.5]
4. What is known as longitude?
Answer: Longitude is the angular distance of a place east or west of the prime meridian. It is also defined as distance, measured in degrees east or west of any fixed meridian.
5. Write the important uses of important longitudes.
Answer: The important uses of important longitudes are:
The utility of Prime Meridian (0° longitude) is:
(i) to know the place whether it is in eastern or western hemisphere.
(ii) To know the distance of a place from the prime meridian.
(iii) To know the time of a place.
The uses of 180° Longitude are:
(i) It helps us to know the date and time of the world.
(ii) It helps us to know the location of places in eastern or western hemisphere.
Longitude, in general, has a definite relation with time. The earth rotates from west to east through 360° in 24 hours, so the sun appears to move from west to east at the rate of 15° per hour or 1° in both the northern and southern hemisphere. When the sun reaches its highest position in the sky for the meridian, Local times (sometimes called suntimes) is considered to be 12 noon.
6. What is earth grid?
Answer: Earth Grid is made up of some perpendicular lines intersecting north-south and east-west forming a network.
7. What is ‘Antipode’?
Answer: Antipodes are two place on the earth surface that are diametrically opposite to each other. If a straight line is drawn through the centre of the earth, it will reach just the opposite side (just on the antipodal position).
8. What is ‘Leap Year’?
Answer: A Leap Year is a year that is divisible by four. For example, 1996 is divisible by four and hence it is Leap Year. A year like 1990 is not divisible by 4, and so it is not a leap year.
9. What is ‘International Date Line’?
Answer: The International Date line may be defined as an imaginary line drawn almost along 180° meridian extending from the north pole to the south pole from which each new date starts and each date ends at last. By international agreement, the correction of date is made along the 180° line of longitude, and this is called the International Date Line.
10. Why the equator is known as the ‘Great Circle’?
Answer: Equator is the only great circle in the earth. Other latitudes are small circles. Because only equator crosses the centre of the earth, the centre of the equator is the ‘Centre of gravity’ of the earth. So Equator is known as the great circle.
Essay type questions
1. How could you determine the latitude of a place on the earth?
Answer: Latitude is the angular distance of a place or point measured from the equator to its north or south. If we draw an imaginary line from any point of earth surface to the centre of the earth, an angle will be formed at the centre, which is the latitude of that place.
In reality we cannot reach the centre of the earth to measure the angle so we need the help of Pole star and the angle of inclination. In northern hemisphere the latitude of a place may be obtained by observing the angle of inclination of the Pole star. The angle that the Pole Star makes at any place on earth in the northern hemisphere is the latitude of the place. In the southern hemisphere a similar fixed star Hadley’s Octant is used to find out a latitude.
The angular distance of the sun and the stars are measured by ‘Sextant’. This instrument measures the angle between the horizon and a celestrial body with the help of the sun during day time and the North star during night.
Also, the Modern GPS System, or Global Positioning System, determines the location of a place by the intersection of latitudes and longitude with the help of satellite.
2. Give the difference between parallels of latitudes and longitude.
Answer: The differences between Parallels of Latitude and Meridians of Longitude are:
| Point of difference | Parallels of Latitude | Meridians of Longitude |
| [A] Orientation | Parallels are extended in east-west direction. | Meridians are extended in north-south direction. |
| [B] Extent | Parallels are extended in east-west direction. | Meridians are extended in north-south direction. |
| [C] Types | They are parallel to each other. | They are not parallel. |
| [D] Highest | The highest possible latitude is 90°. | The highest possible longitude is 180°. |
| [E] Total No. | There are 89 parallels in both the hemisphere at an interval of 1°. The total is 179. | There are 180 meridians in both the hemisphere. The total in 360. |
| [F] Length | From the equator towards the poles the parallels are getting smaller in length. | Meridians remain uniform in length. |
| [G] Climate | Parallels are related to climatic belts. | Meridians are related to local time. |
| [H] Angle | Total angular measurement is 360°. | Total angular measurement is 180. |
3. What is the difference between ‘local time’ and ‘standard time’.
Answer: Local Time is based on the principle that all the places on the same meridian of longitude have noon at the same time. This is called local time for the particular place. Places located on different meridians have different local time. If the watches of a place are set by this noon time, they will show the local time of that place.
Standard Time addresses the issue that local time differs from place to place, which causes great inconvenience for a country as a whole. To overcome this inconvenience, the local time of a central meridian is taken as the time for the whole country. This is called standard time. For example, in India the longitude of 82°30′ E passing through Allahabad is considered the Standard Meridian, and the time is taken as noon for the whole country when it is noon on this longitude. This is known as the Indian Standard Time (IST).
4. How do you locate a place by ‘Earth Grid’ ?
Answer: Earth Grid is made up of some perpendicular lines intersecting north-south and east-west forming a network. To locate a point on a grid, we have to mention the letter first and the number next. In a grid, each line (east-west) is marked as 1, 2, 3, 4, and the lines running North-south is marked as A, B, C, D, E. For example, in the figure the location of ‘S’ is C2.
5. Find out the longitude of E. Newyork when it is 6.30 a.m. at Chennai (80°E) and 8.13 p.m. in the previous night at New York.
Answer:
Determine the Time Difference:
- Time in Chennai: 6:30 a.m. on a specific day.
- Time in New York: 8:13 p.m. on the previous day.
- To find the difference, calculate the time from 8:13 p.m. (previous day) to 6:30 a.m. (current day).
- Time from 8:13 p.m. to midnight (00:00) = 3 hours and 47 minutes.
- Time from midnight (00:00) to 6:30 a.m. = 6 hours and 30 minutes.
- Total time difference = (3 hours 47 minutes) + (6 hours 30 minutes) = 9 hours 77 minutes = 10 hours and 17 minutes.
- Since Chennai’s time is ahead (later in the day/next day), New York is to the West of Chennai.
Convert Time Difference to Longitude Difference:
- The Earth rotates 15° of longitude every hour (360° / 24 hours).
- This means 1° of longitude corresponds to 4 minutes of time (60 minutes / 15°).
- Convert the time difference (10 hours 17 minutes) into degrees:
- For the hours: 10 hours * 15°/hour = 150°.
- For the minutes: 17 minutes / 4 minutes/degree = 4.25°.
- Total longitude difference = 150° + 4.25° = 154.25°.
- Converting 0.25° to minutes of arc: 0.25 * 60′ = 15′.
- So, the precise longitude difference is 154° 15′.
Calculate New York’s Longitude:
- Chennai is at 80°E.
- New York is 154° 15′ West of Chennai.
- Starting from 80°E, move 154° 15′ westward.
- Moving 80° west from 80°E brings us to the Prime Meridian (0°).
- We need to move further west by the remaining amount: 154° 15′ – 80° = 74° 15′.
- Moving 74° 15′ west from the Prime Meridian (0°) results in a longitude of 74° 15′ W.
Conclusion based on Calculation:
The calculation based on the exact times given (6:30 a.m. and 8:13 p.m.) results in a longitude of 74° 15′ W for New York.
6. Find out the Indian Standard time when it is 12 noon at Chronometre?
Answer: A Chronometer is an instrument or watch which keeps extremely accurate time of Greenwich. It denotes the Greenwich time (G.M.T.). Therefore, 12 noon at Chronometre means 12 noon G.M.T.
Indian Standard Time (IST) is 5 1/2 hrs. ahead of Greenwich Mean Time.
To find the Indian Standard Time when it is 12 noon at Chronometre (G.M.T.), we need to add 5 hours and 30 minutes to 12 noon G.M.T.
Calculation:
12:00 noon G.M.T. + 5 hours 30 minutes = 17:30 hours IST
Converting 17:30 hours to the 12-hour format:
17:30 hours = 5:30 p.m.
So, the Indian Standard Time is 5.30 p.m.
7. A telegram is send from Washington (77°W) on 31Dec. 1998 at 8.30 p.m. to Allahabad (82°30’E). It takes 15 minutes to reach. Calculate the date and time, the telegram reaches at Allahabad.
Answer: To calculate the arrival date and time of the telegram in Allahabad, we need to determine the time difference between Washington and Allahabad based on their longitudes and then add the transmission time.
Calculate the difference in Longitude:
- Washington is located at 77° West longitude.
- Allahabad is located at 82°30′ East longitude.
- Since the locations are in opposite hemispheres (West and East of the Prime Meridian 0°), the total difference in longitude is the sum of their longitudes:
Difference = 77° + 82°30′ = 159°30′
Calculate the Time Difference:
- The Earth rotates 360° in 24 hours.
- Therefore, the time difference for 1° of longitude is 4 minutes (24 hours * 60 minutes/hour / 360° = 1440 minutes / 360° = 4 minutes/°).
- Alternatively, the Earth rotates 15° in 1 hour (360° / 24 hours = 15°/hour).
- Time difference for 159° = 159 * 4 minutes = 636 minutes.
- Time difference for 30′ (which is 0.5°) = 0.5 * 4 minutes = 2 minutes.
- Total time difference = 636 minutes + 2 minutes = 638 minutes.
- Convert the total time difference into hours and minutes:
638 minutes / 60 minutes/hour = 10 hours and 38 minutes.
Determine the Local Time in Allahabad when the telegram was sent:
- Allahabad is East of Washington. As the Earth rotates from West to East, locations to the East have time ahead of locations to the West.
- Therefore, the local time in Allahabad is 10 hours and 38 minutes ahead of Washington’s local time.
- The telegram was sent from Washington at 8:30 p.m. on 31st December 1998. In 24-hour format, this is 20:30 on 31st Dec 1998.
- Local time in Allahabad when sent = Washington time + Time Difference
= 20:30 on 31st Dec 1998 + 10 hours 38 minutes
= 30 hours 68 minutes from the beginning of 31st Dec 1998
= 31 hours 08 minutes from the beginning of 31st Dec 1998 - Since a day has 24 hours, 31 hours 08 minutes means 24 hours (1 full day) + 7 hours 08 minutes.
- So, the time in Allahabad when the telegram was sent was 7:08 a.m. on the next day, which is 1st January 1999.
Calculate the Arrival Time in Allahabad:
- The telegram took 15 minutes to reach.
- Arrival Time = Time when sent (Allahabad local time) + Transmission Time
= 7:08 a.m. on 1st Jan 1999 + 15 minutes
= 7:23 a.m. on 1st Jan 1999.
Therefore, the telegram reaches Allahabad at 7:23 a.m. on 1st January 1999.
8. A special news (radio) bulletine has been delivered from New York [74°W] at 12 noon and is heard/received at a place at 8pm. Find out the longitude of that place.
Answer:
Find the time difference:
- Time at New York = 12 noon
- Time at the place where the bulletin is heard = 8 pm
- The time difference is 8 pm – 12 noon = 8 hours.
Determine the direction:
- Since the time at the unknown place (8 pm) is later than the time at New York (12 noon), the place is located to the east of New York.
Calculate the longitude difference:
- The Earth rotates 360° in 24 hours.
- Therefore, the rate of rotation is 360° / 24 hours = 15° of longitude per hour.
- The longitude difference corresponding to a time difference of 8 hours is:
Longitude Difference = 8 hours × 15°/hour = 120°.
Calculate the longitude of the place:
- New York is located at 74°W longitude.
- The unknown place is 120° east of New York.
- To find the longitude, we start at 74°W and move 120° eastward.
- Moving 74° east from 74°W brings us to the Prime Meridian (0° longitude).
- We need to move further east by the remaining difference: 120° – 74° = 46°.
- Moving 46° east from the Prime Meridian (0°) places us at 46°E longitude.
Therefore, the longitude of the place where the news bulletin was heard at 8 pm is 46°E.
Extras
Additional MCQs
1. What is the shape of the Earth?
A. Sphere
B. Cylinder
C. Oblete spheroid
D. Cube
Answer: C. Oblete spheroid
50. In a grid reference system, the order used to cite a location is ___.
A. Letter then number
B. Number then letter
C. Latitude then longitude
D. East then west
Answer: A. Letter then number
Additional Questions, Answers
1. What is the shape of the Earth?
Answer: The Earth is an Oblete Spheroid.
35. Define antipodes and outline the method for calculating the antipodal latitude and longitude of a given location.
Answer: Antipodes are two places on the earth surface that are diametrically opposite to each other. If a straight line is drawn through the centre of the earth, it will reach just the opposite side (just on the antipodal position).
Determination of Antipodes: Antipodes of any place can be determined by the following ways:
(a) According to Latitude: The latitudes of antipodes are always equal in degree (°), minute (‘) and second (´´) and interchange the hemisphere [one north; the other south]. Example: The latitude of Kolkata is 22°34′ N. The antipodes of Kolkata is 22°34′ S.
(b) According to Longitude: The difference in longitude between a place and its antipode is always 180°. In this case, the given longitude will be subtracted from 180° and the result will be in opposite hemisphere. Example: Longitude of Kolkata is 88°24′ E. So longitude of its antipodes is (180° – 88°24′) = 91°36′W.
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger who manages Online Free Notes. An avid reader of Victorian literature, his favourite book is Wuthering Heights by Emily Brontë. He dreams of travelling the world. You can connect with him on social media. He does personal writing on ronism.
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