Why do we need to locate places on Earth?
Answer
We need to locate places on earth because:
- It helps us to know the exact position of places.
- It helps to find distance between two places if their exact positions are located.
- It gives us an idea to locate physical features, villages, cities etc.
- Finding location helps us to design various infrastructures like roads, railways.
What do you mean by the latitude of a place?
Answer
The latitude of a place is the angular distance of that place North or South of the equator, as measured from the centre of the earth.
What is meant by Prime Meridian?
Answer
The 0° longitude passing through Greenwich near London is called the Prime meridian.
Explain why there is no higher latitude other than 90 degrees North and South.
Answer
There is no higher latitude other than 90 degrees North and South because lines of latitude start at 0° (equator) and end at 90° (poles). All planes make a maximum angle of 90° from the plane of the equator.
Explain why Lines of Longitudes are called Meridian of Longitude.
Answer
The Lines of Longitudes are called Meridian of Longitude because the word 'meridian' means "midday" and all the places on the same meridian have their noon at the same time.
State two properties of the Lines of Latitude.
Answer
Two properties of the Lines of Latitude are:
- Each latitude is an imaginary circle parallel to the equator and centered on the polar axis.
- The radius and the length of parallels gradually decrease from its maxima at the equator to its minima at the poles.
State two properties of Lines of Longitude.
Answer
Two properties of Lines of Longitude are:
- All meridians are complete circles dividing the earth into Eastern and Western Hemisphere.
- The longitudes are drawn 1° apart on the Equator, with 1° to 179° towards east and 1° to 179° towards west.
The distance between two successive parallels of latitudes is 111 km. Explain.
Answer
The whole earth represents 360° and the circumference of the earth is approximately 40,000 km. Therefore, for each degree i.e. the difference between two latitudes is 111km (i.e 40000 divided by 360).
What are the limits of two Temperate Zones?
Answer
The limit of northern temperate zone is 23 1/2°N to 66 1/2°N and the limit of southern temperate zone is 23 1/2°S to 66 1/2°S. The temperate zone stretches from Torrid zone to Frigid zone.
Why are the places in the Torrid Zone hotter than those in other zones?
Answer
The Torrid zone or the tropical zones lie between the Tropic of cancer and Tropic of Capricorn which mark the limit of the overhead Sun to North and South of the Equator, i.e., 23 1/2°N to 23 1/2°S. This area receives direct sun rays and therefore, the places in the Torrid Zone are hotter than those in other zones.
Why are the places in the Frigid Zone colder than in other zones?
Answer
The Frigid Zone experiences colder temperatures compared to other zones due to the inclination of the earth's axis, which results in the area receiving oblique rays of sunlight during the winter.
How is the Local Time of a place fixed?
Answer
The Local Time of a place is fixed according to the central meridian of its country. When the sun is overhead on the central meridian it is 12 o'clock noon at that place. For example, the central meridian of India is 82 1/2° E and passes through Allahabad and it is the standard time line for the whole country.
Is it correct to say that Local Time is the Sun Time?
Answer
Yes, it is correct to say that Local Time is the Sun Time because local time is determined based on Sun's apparent movement.
If the GMT at 0° longitude is 12 noon, find the local time of place A (30°E).
Answer
The difference in longitude between 0° and place A is 30° towards east.
Since, for every 1° difference in longitude the difference of time is 4 minutes.
Therefore, the local time of place A will be 30 x 4 = 120 minutes = 2hrs.
As, A is located to the east, it will be 2 hours ahead of Greenwich time: 12 + 2 = 14hr or 2 pm.
Therefore time at place A will be 2 pm.
Why is the Standard Time considered necessary?
Answer
The Standard Time is considered necessary because if every city had to keep the time of their own meridian, there would have been much difference in the local time of one city and the other. This would have led to a lot of confusion.
What are Time Zones? How many Time Zones do we have?
Answer
A zone on terrestrial globe that is approximately 15° longitude wide with 1 hour difference in time from other zone, is called time zone. The world is divided into 24 time zones and India has one time zone.
London experiences a lower temperature than Singapore throughout the year. Why?
Answer
Singapore is situated in torrid zone, near the equator while London is located in temperate zone. Torrid zone receives direct sun rays and is hotter than the temperate zone which receives slant rays of the sun. Therefore, London experiences a lower temperature than Singapore throughout the year.
What is International Date Line? Describe the use of this line.
Answer
A zigzag line at roughly 180° meridian is the line which is internationally adopted as International Date Line or IDL. On either side of this line, a difference of whole day is observed. This is because the earth completes one rotation on its axis in 24 hours as it rotates from west to east.
International Date Line is for the convenience of those travelling round the world in order to avoid any confusion.
Why do some countries have many Time Zones?
Answer
Some countries have large longitudinal extent and therefore they have many tine zones.
What are Small Circles?
Answer
The 0° latitude that circumscribes the earth around it's centre is called Equator or the great circle and all other circles that do not circumscribes the earth around it's centre are called small circles.
Except for the Equator, other Parallels of Latitudes are not Great Circles. Why?
Answer
The equator is the only latitude that circumscribes the earth around it's centre and therefore it is the largest latitude. All other latitudes, either in north or in south, are smaller than equator because they do not circumscribe the earth around its centre.
How is the use of local time inconvenient in practical life?
Answer
The use of local time is inconvenient in practical life because local time is different in different countries. For those travelling abroad, it is very confusing to have different time zones.
What is a Grid?
Answer
A grid is a network of evenly spaced horizontal and vertical lines used to identify locations on a map. Earth's grid refers to the network of latitudes and longitudes on the earth's surface.
Who was the first mathematician to have measured the circumference of the Earth?
Answer
The first mathematician to have measured the circumference of the Earth was Eratosthenes.
Name the important Climatic Zones of the World.
Answer
The important Climatic Zones of the World are:
- The Torrid or tropical zones
- Temperate zones
- Frigid zones
State the rate of change of time with longitude.
Answer
For every 1° change in longitude, the change in time is 4 minutes.
Explain how latitudes and longitudes help to locate position of a place on a globe.
Answer
The latitudes and longitudes are horizontal and vertical lines which form a grid on the globe or map. We can easily locate a place on the globe if we have its longitudinal and latitudinal positions. The point of intersection of its latitude and longitude will determine the position of that place on globe.
Answer the following questions based on the below diagram:
- What does PP' represent?
- What does TT' represent?
- What is the latitude of place X?
Answer
- Latitude
- Longitude
- 40° N
Distinguish between:
- Local Time and Standard Time
- Parallels and Meridians
- Equator and Prime Meridian
Answer
- Difference between Local Time and Standard Time:
| S. No. | Local Time | Standard Time |
|---|---|---|
| 1. | Local time of a place can be calculated if we know the longitude of the place. | Local time of a country's central meridian is the standard time of the country. |
| 2.. | Local time changes with longitude. | It remains same within a country. |
- Difference between Parallels and Meridians:
| S. No. | Parallels | Meridians |
|---|---|---|
| 1. | They are the imaginary circles parallel to the equator. | These are the imaginary lines running from the north pole to the south pole. |
| 2. | They never intersect each other. | They intersect at north and south pole. |
| 3. | They are also known as latitudes. | They are also known as longitudes. |
| 4. | They vary in length. | They have same length. |
- Difference between Equator and Prime Meridian:
| S. No. | Equator | Prime Meridian |
|---|---|---|
| 1. | It is the latitude of 0° that circumscribes the earth around its centre. | It is the longitude of 0° which passes through Greenwich near London. |
| 2. | It divides the earth into Southern and Northern hemisphere. | It divides the earth into Eastern and Western hemisphere. |
When it is noon at England, what will be the time in India?
Answer
The longitudinal difference between England and India: is 82° 30'.
For 1° longitudinal difference time is 4 minutes.
So, for 82° 30' longitudinal difference is 82° 30' x 4 = 330 minutes or 5 hours 30 minutes.
As India is situated in the east of England, the local time of India will be ahead the time of England.
The local time of India will be: 12 noon + 5 hours 30 minutes = 5:30 pm.
What is the time at New York (74° W) when it is noon at Greenwich?
Answer
The longitudinal difference between New York and Greenwich is: 74°
For 1° longitudinal difference time is 4 minutes.
So, for 74° longitudinal difference the time difference is: 74° x 4 = 296 minutes or 4 hours 56 minutes.
As New York is situated in the west of Greenwich, its local time will be behind the time of Greenwich.
The local time of New York will be: 12 noon - 4 hours 56 minutes = 7:04 am.
When it is 10 pm. in India, what is the local time at Helsinki located at 20° E longitude?
Answer
The longitudinal difference between Helsinki and India is: 82° 30' - 20° = 62° 30'
For 1° longitudinal difference time is 4 minutes.
So, for 62° 30' longitudinal difference the time difference is 62° 30' x 4 = 250 minutes or 4 hours 10 minutes.
As Helsinki is situated in the west of India, the local time of Helsinki will be behind the time of India.
The local time of Helsinki will be: 10 pm - 4 hours 10 minutes = 5:50 pm.
Find out the local time in Auckland (175° E) when it is 2 p.m. in Wollongong (150° E).
Answer
The longitudinal difference between Auckland and Wollongong is: 175° - 150° = 25°
For 1° longitudinal difference time difference is 4 minutes.
So, for 25° longitudinal difference time difference is 25° x 4 = 100 minutes or 1 hour 40 minutes.
As Auckland is situated in the east of Wollongong, the local time of Auckland will be ahead the time of Wollongong.
The local time of Auckland will be: 2 pm + 1 hours 40 minutes = 3:40 p.m.
If the time at village A (75°W) is 5:00 pm on Friday, calculate the time & day at village B (120°E).
Answer
The longitudinal difference between village A and village B is: 120° + 75° = 195° (as different hemisphere).
For 1° longitudinal difference time is 4 minutes.
So, for 195° longitudinal difference the time difference is: 195° x 4 = 780 minutes or 13 hours.
As village B is situated in the east of village A, its local time will be ahead the time of village A.
The local time of village B will be: 5pm + 13 hours = 6 a.m. on Saturday.
Latitude
Answer
The latitude of a place is the angular distance of that place North or South of the equator, as measured from the centre of the earth.
Longitude
Answer
The longitude of a place is the angular distance of that place east or west of the prime meridian.
Meridian
Answer
The imaginary lines or semi-circles that connect north pole and south pole are called meridian.
Prime Meridian
Answer
Prime Meridian is the longitude of 0° which connects north and south poles and passes through Greenwich near London.
Local time
Answer
When the sun is overhead at a place, the local time is 12 o'clock noon at that place. Local time of a place can also be calculated if we know the longitude of the place.
Standard time
Answer
Standard time of a country is defined as the local time of its central meridian which is observed throughout the country.
Indian Standard Time
Answer
The longitude of 82 1/2°E is the central meridian of India which passes through Allahabad. Its local time is the standard time for the country and is known as Indian Standard Time.
Greenwich Mean Time
Answer
The local time of zero degree meridian which passes through the Royal Astronomical Observatory at Greenwich, is taken as international standard time and is known as Greenwich Mean Time.
International Date Line
Answer
The longitude at 180° is considered as International Date Line as on either side of this line, a difference of one whole day is observed.
Great circle
Answer
The latitude at 0° which circumscribe the earth around it's centre and divides the earth into two hemispheres is called Great circle.
Small circle
Answer
All other latitudes except the equator are smaller (than the equator) and are known as Small circles.
Grid
Answer
A grid is a network of evenly spaced horizontal lines (latitudes) and vertical lines (longitudes) used to identify locations on a map.
Latitude and Longitude.
Answer
| S. No. | Latitude | Longitude |
|---|---|---|
| 1. | It is the angular distance of a point, north or south of the equator, as measured in degrees. | It is the angular distance along the equator measured in degrees. It is measured east or west of Greenwich 0° to 180°. |
| 2. | All latitudes are parallel to the equator. | All meridians of longitude converge at the poles. |
| 3. | The distance between two latitudes is approximately 111 km throughout. | The distance between two longitudes is maximum at the equator and goes on decreasing as one goes towards the poles. |
| 4. | There are 90° of latitudes in the north and 90° latitudes south of the equator. | There are 360° of longitude, 180° each in east and west of the Prime Meridian. |
| 5. | The latitudes from equator to poles are used to demarcate temperature zones. | The longitudes are used to determine the time with reference to the time at Prime Meridian (GMT). |
Great Circle and Small Circle
Answer
| S. No. | Great Circle | Small Circle |
|---|---|---|
| 1. | The 0° latitude is known as Great Circle. | All other latitudes except the Great circle are Small circles. |
| 2. | It is also known as equator. | They are also known as parallels of Latitude. |
Greenwich Mean Time and Indian Standard Time
Answer
| S. No. | Greenwich Mean Time | Indian Standard Time |
|---|---|---|
| 1. | The local time of zero degree meridian which passes through the Royal Astronomical Observatory at Greenwich, is known as Greenwich Mean Time. | The longitude of 82 1/2°E is the central meridian of India which passes through Allahabad. Its local time is known as Indian Standard Time. |
| 2. | It is taken as International Standard Time. | Its local time is the standard time for India. |
Latitudes and Longitudes are always expressed in angles.
Answer
Latitudes and Longitudes are always expressed in angles because they represent angular distance as the earth is spherical in shape.
Large countries have many time zones.
Answer
Large countries have larger longitudinal extent and therefore they have many time zones. For example, Canada has 6 time zones.
The international Date Line is not a straight line like other longitudes.
Answer
The International Date Line is not a straight line like other longitudes because in order to avoid any landmass, deviation has been taken. It is done to avoid the confusion of having different dates in the same country.
A person gains time as he travels towards east.
Answer
A person gains time as he travels towards east because the earth rotates from west to east. Places on the east of a given point on the earth are ahead of time.
The intervals between successive parallels are constant.
Answer
The intervals between successive parallels are constant because the latitudes are parallel and equidistant to each other.
A person travelling from Mumbai to London has to alter his watch.
Answer
A person travelling from Mumbai to London has to alter his watch because both the cities are in different time zones.
The difference between I.S.T. and the G.M.T. is 5 hours and 30 minutes.
Answer
The difference between longitudes of I.S.T. and the G.M.T. = 82 1/2°
Since, the difference of 1° in longitude = a difference of 4 minutes
Therefore, for difference of 82 1/2°, the difference in time = 4 x 82 1/2 = 330 minutes = 5 hrs 30 min.
Parallels are not equal in length.
Answer
Since shape of the Earth is an oblate spheroid, the radius and length of parallels gradually decrease from its maxima at the Equator to its minima at the Poles. Hence, parallels are not equal in length.
Navigators use Great circle route for navigation.
Answer
Navigators use Great circle route for navigation because Great circle routes are the shortest distance between the two places on the Earth. They help to save fuel and time so they are very economical.
Parallels of Latitude
Answer
Below diagram shows Parallels of Latitude:
Temperature Zones
Answer
Below diagram shows Temperature Zones:
Earth's Grid
Answer
Below diagram shows Earth's Grid:
Earth is divided into Northern & Southern Hemisphere by which of the following imaginary line?
- Prime Meridian
- Tropic of Cancer
- Equator
- International Date Line
Answer
Equator
What is the latitude of Arctic Circle?
- 66 1⁄2°S
- 23 1⁄2°S
- 66 1⁄2°N
- 23 1⁄2°N
Answer
66 1⁄2°N
How many total parallels of latitudes are there in the world?
- 90
- 91
- 180
- 181
Answer
181
Refer to the image and identify the climatic zone of the shaded region.
- North Frigid Zone
- North Temperate Zone
- Torrid Zone
- South Frigid Zone
Answer
Torrid Zone
There is a time difference of ............... for every 1° of longitudinal difference.
- 2 minutes
- 4 minutes
- 1 hour
- 60 seconds
Answer
4 minutes
What is the full form of IDL?
- International Diagonal line
- Internal Detour Line
- International Date Line
- Intermediate Diagonal Line
Answer
International Date Line
Which of the following meridian is called the Central Meridian of India?
- 83 1⁄2°W
- 0°
- 82 1⁄2°E
- 72°E
Answer
82 1⁄2°E
USA has ............... time zones.
- 8
- 11
- 6
- 7
Answer
6
Which of the following statements related to lines of latitude is not correct?
- They are called parallels of Latitude.
- They are used to determine time.
- They are important to determine climate.
- Equator is the largest line of latitude.
Answer
They are used to determine time
Meridian means
- Midnight
- Midday
- Morning
- Dusk
Answer
Midday
The difference between IST & GMT is
- 6 hours
- 4 hours 30 minutes
- 5 hours 30 mins
- 12 hours
Answer
5 hours 30 mins
Which of the following statement about Great circle is true?
- All the parallels are Great circles.
- Navigators find it difficult to follow the route of Great circle.
- Equator & all the meridians are Great circles.
- All the above.
Answer
Equator & all the meridians are Great circles.
World is divided into ............... time zones.
- 20
- 5
- 11
- 24
Answer
24
Arunachal Pradesh Chief Minister Pema Khandu demanded for a separate time zone for north-eastern states. Khandu said 'We get up as early as 4 am. Several daylight hours are wasted as government offices open only at 10 am and close at 4pm. Leaders from the region argue that a separate time zone would increase daylight savings and efficiency.
As a student of Geography explain the reason for the wasting of daylight hours in Arunachal Pradesh as told by Khandu.
Answer
Arunachal Pradesh lies in the easternmost part of India, where the sun rises and sets much earlier than in the rest of the country. Since India follows a single standard time, government offices there start at 10 am, by which time a significant portion of daylight has already passed. As a result, valuable daylight hours are lost, reducing the number of productive working hours for people in the region.
The history of the International Date Line dates back to the Christian era 1522, when Magellan's crew reached home after circumnavigating the world for the first time by ship. They thought it was 5th September but actually they reached on 6th September. Why was it happened?
Answer
This happened because Magellan’s crew had unknowingly crossed the 180° meridian during their journey. When a ship travels around the world and crosses this line from west to east, it gains a day due to the 24-hour time difference on either side of the 180° meridian. So, although they believed it was 5th September, the actual date was 6th September.
Assertion (A): Navigators and aviators follow Great circle routes.
Reason (R): Great circle routes are the shortest route on the earth surface.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — Since great circle routes are the shortest distance between the two places on the Earth and lie on the arc of a Great Circle, they are the most advantageous routes for navigators and aviators to follow.
Assertion (A): IST is 5 hours 30 minutes ahead of GMT.
Reason (R): India is situated in the west of London.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
A is true but R is false.
Explanation — IST is 5 hours 30 minutes ahead of GMT because India lies to the east of London, not the west. As the Earth rotates from west to east, places to the east of the Prime Meridian (Greenwich) are ahead in time.