Latitudes, Longitudes & Altitude अक्षांश, देशांतर, ऊंचाई

            Latitudes and longitudes are imaginary lines, which are used to locate points on the earth’s surface, measured in degrees. 

            Latitudes are also known as parallels while longitudes are termed as meridians.

Latitude  अक्षांश

Latitude is defined as the angular distance of any point, north or south of the equator, i.e., Latitude is a measurement on a globe or map of location north or south of the Equator.  It is measured in degrees, minutes and seconds or decimal degrees, north or south of the equator. [It is usually denoted by the Greek lower-case letter phi (φ or ϕ).] 

An equator (भूमध्य रेखा)  is an imaginary circular line drawn on the earth, which divides it into two equal parts, wherein the upper half is called Northern Hemisphere  (उत्तरी गोलार्द्ध), and the lower half is known as Southern Hemisphere (दक्षिणी गोलार्द्ध). The circular lines, parallel to the equator, up to the North and South poles are the parallels of latitude.

Latitude ranges from 0 degrees to 90 degrees, wherein equator indicates 0° latitude and 90° is at the poles. The parallels lying in the northern hemisphere are considered as north latitudes and are indicated as N, while those lying in the southern hemisphere are called south latitudes, and are indicated as S. Some major parallels of latitude are:

• Tropic of Cancer (23.5° N) कर्क रेखा
• Tropic of Capricorn (23.5° S) मकर रेखा
• Arctic Circle (66.5° N) आर्कटिक वृत्त
• Antarctic Circle (66.5° S) अण्टार्कटिक वृत्त
• North Pole (90° N) उत्तरी ध्रुव
• South Pole (90° S)  दक्षिणी ध्रुव

Features of Latitudes  (अक्षांश की विशेषताएं):

• There are 181 latitudes in all (The Equator at 0° and 90 above it and 90 below it)
• All the latitudes are complete circles except the North and South Poles, which are merely points on the tilted axis of the Earth (पृथ्वी की धुरी).
• Equator, the central latitude is the longest and they keep on becoming smaller in size as they move away from it.
• Only Equator divides the earth in 2 equal halves and no other latitude divides the earth likewise.
• All the latitudes are equidistant & parallel to each other. No two latitudes meet.

Longitudes  देशांतर

Longitude is a geographic coordinate that specifies the east–west position of a point on the Earth‘s surface, [or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letterlambda (λ).]

Meridians (lines running from pole to pole) connect points with the same longitude. The longitudes are of equal lengths and are 360 in number.

The Central longitude which divides the earth into the Eastern (पूर्वी गोलार्ध)  and the Western Hemisphere (पश्चिमी गोलार्ध्द) is known as The prime meridian.  It is defined as 0° longitude by convention.  It passes by the point near the Royal Observatory, Greenwich, England.  [Note the point ‘by convention’, It means that it could have been considered anywhere in the world – Even in India.]

Positive longitudes are east of the prime meridian, and are numbered from 1° E to 179° E. Meridians to the west are called negative ones or the west Meridians and are numbered from 1° W to 179° W.  The meridian of 180° E and 180° W is the same line.  It passes through the islands of the Pacific Ocean.  It is called the International Date Line (IDL) (अंतर्राष्ट्रीय दिनांक रेखा).  A new date begins when we pass it.

[IDL is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and island groups.]

[Because of the earth’s rotation, there is a close connection between longitude and time. Local time (for example from the position of the sun) varies with longitude, a difference of 15° longitude corresponding to a one hour difference in local time. ]

Longitudes are also known as Nenchans, which means midday in Latin.  [In fact Noon (or midday) is 12 o’clock in the daytime, and is written as 12 noon, 12 p.m. (for post meridiem) or 12 pm. At this time the Sun appears to contact the local celestial meridian; i.e. it reaches its highest point in the sky, marking it the midday at that place.]

[Standard Meridian – The meridian used for reckoning standard time of any country.  In hindi we call it मानक मध्याह्न रेखा. ]

The standard meridian of India is 82.5°east of the Greenwich meridian. It passes through Allahabad & Mirzapur, city in uttarpradesh.  It is the basis of Indian Standard Time (IST).  When sun shines over this meridian, in India the time is considered to be 12 noon.  IST is ahead of GMT by five and a half hours.

Features of Longituds

• All the meridians are of equal lengths and meet at poles.
• Longitudes cross the latitudes at right angles.
• Meridians opposite to each other may be considered to form great circles which can divide the earth into two equal halves.
• The distance between any two longitudes decreases as one moves away from the equator towards the pole.

[Key Differences Between Latitude and Longitude –

1. The geographic coordinates which ascertain the distance of a point, north-south of the equator, is called latitude. The geographic coordinate, which identifies the distance of a point, east-west of the Prime Meridian, is termed as longitude.
2. The direction of latitude is east to west, which is parallel to the equator. On the contrary, the direction of longitude is north to south, intersecting the two poles.
3. Greek letter phi (ɸ) is used to represent latitude. Conversely, Greek letter lambda (λ), is a symbol for longitude.
4. The range of latitudes is from 0 to 90 degrees, but the longitudes range from 0 to 180 degrees.
5. The parallel circles from the equator to the north and south poles are termed as parallels of latitude. As opposed, the lines of reference, running from the two poles is known as meridians of longitude.
6. The total number of latitude lines are 181. Unlike, there are a total number of 360 longitude lines.
7. The parallels of latitude are of unequal length, whereas the meridians of longitude are of equal length.
8. In latitude, the lines of references are parallel to each other. On the flip side, in longitude, the lines of references are not parallel to each other.
9. Latitudes are used to categorise heat zones, i.e. torrid zone, temperate zone and frigid zone. In contrast, longitudes are used to classify time zones.

GRIDS

The grid helps people locate places on the map. On small-scale maps, the grid is often made up of latitude and longitude lines. The intersection of latitude and longitude lines, called coordinates, identify the exact location of a place. [On maps showing greater detail, the grid is often given numbers and letters.]

The Greenwich Mean Time (GMT) (ग्रीनविच मीन टाइम)

It has been stated above that, ‘The Central longitude which divides the earth into the Eastern and the Western Hemisphere is known as The prime meridian.  It is defined as 0° longitude by convention.  It passes by the point near the Royal Observatory, Greenwich, England.  When Sun in above it it is 12 noon as per GMT.

Japan is the first country to receive sunlight of the day and America the last country

Lastly, Altitude should not be confused with latitude as latitude is used to locate point on the earth’s surface whereas altitude is the height at that point.   [Altitude or height (also sometimes known as ‘depth’) is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, atmospheric pressure, and many more). As a general definition, altitude is a distance measurement, usually in the vertical or “up” direction, between a reference datum and a point or object. The reference datum also often varies according to the context. Although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage.]

Related Questions

1. What is the 0° meridian called? a) Prime meridian, b) Equator, c) Arctic Circle
2. GMT stands for – a) Indian Standard Time, b) Greenwich Mean Time, c) Grid
3. The largest latitude is – a) Tropic of Cancer, b) Tropic of Capricorn, c) Equator
4. What is the other name of a Longitude?
5. What are the structures called which form from the intersection of longitudes and latitudes?
6. Latitudes are horizontal lines running from ____________to_______
7. The countries towards the ___________of the Prime meridian faces the sun first.
8. Is IST five and a half hours ahead of GMT?
9. Is Africa the largest continent on the earth?
10. Do Grids help us to locate the places exactly on the globes?
11. Does the equator divide the earth into 2 equal halves?
12. What are latitudes? Name the important ones.
13. What are longitudes? Name the important ones.
14. What is grid system, and how is it useful?
15. How is IST calculated?
16. The Sun rises two hours earlier in Arunachal pradesh as compared to Gujarat in the West but the watches show same time all over the India. How is it possible?

ANSWERS

1. a
2. b
3. c
4. meridians
5. grid
6. East to West
7. East
8. Yes
9. No
10. Yes
11. Yes
12. Latitude is the measurement of distance north or south of the Equator. It is measured with 181 imaginary lines that form circles around the Earth east-west, parallel to the Equator. These lines are known as parallels. The important latitudes are:

• Tropic of Cancer (23.5° N)
• Tropic of Capricorn (23.5° S)
• Arctic Circle (66.5° N)
• Antarctic Circle (66.5° S)
• North Pole (90° N)
• South Pole (90° S)

13. Longitute is distance measured in degrees east or west of an imaginary line that runs from the north pole to the south pole and passes through Greenwich, England.

Important Longitudes are:

• The prime meridian
• International Date Line
• Standard Meridian

14. The grid is a network of latitude and longitude lines on the globe which helps people locate places on the map. The intersection of latitude and longitude lines, called coordinates, identify the exact location of a place.

15. Indian Standard Time is calculated on the basis of 82.5°E longitude in the city of Mirzapur, Uttar Pradesh, which is situated approximately on the corresponding longitude reference line.

It is 5 hours and 30 minutes ahead of GMT.

16. Standard Meridian of India has been decided to be 82.5° which is the basis of Indian Standard Time. All the watches in India are synchronised according to this time only., hence the same time all over India.