Latitude & Longitude of India UPSC Notes: Parallels, Meridians, & Differences

Latitude and longitude are the imaginary lines running on the surface of the earth used as reference points to locate any specific place on the Earth’s surface. The network of Meridians and Parallels on the map is called the Grid System. The grid system of Meridians and Parallels formed on the map are usually called Squares. The intersection of these Longitudes and Latitudes helps us to pinpoint any specific location on the Earth. Longitudes are also of much importance as they help determine the local time of a place. 

The concept of Latitude and Longitude UPSC is very important for UPSC Exams as, time and again, questions have been asked from this section.

In this article on the Latitude and Longitude notes for UPSC, we will learn the important parallels, the heat zones, the meridians, the time zones, & the difference between latitudes and longitudes as required for UPSC.

अक्षांश और देशांतर UPSC नोट्स हिंदी भाषा में भी पढ़ सकते हैं!

What is Latitude and Longitude of Earth?

Latitude and longitude are special lines that help us find places on Earth, just like street addresses help us find houses. Latitude is like a street name that runs east-west, and longitude is like a house number that runs north-south. Together, latitude and longitude give us a unique address for every place on Earth.

Fig: Latitude and Longitude on a Globe

Fig: India map with latitude and longitude

Check out other important concepts on Indian Geography here.

About Latitude

Latitude is an angular distance of a point on the surface of the earth calculated in degrees from the center of the earth, which is taken as the equator. Other important points related to Latitude are mentioned below.

• Latitudes are parallel circles running from the Equator to the Poles on the surface of the earth.
• Latitudes are the location of any place north or south of the Equator.
• Lines that join the places having the same latitudes are called “Parallels,” i.e., Parallels of Latitude.
• All latitudes are marked North (N) or South (S), taking into account Equator. For example, the Latitude of Chennai is 13𝆩N.
• The Equator is represented as Zero degrees, and the North pole is marked as Ninety degrees North, and the south pole as Ninety degrees South.
• All the Latitudes are drawn at an interval of one degree to the equator.
• There are a total of 179 parallels of Latitude: 89 in the Northern Hemisphere, 89 in the Southern Hemisphere, and one in the Equator.
• The most important latitudes are the Equator, Tropic of Cancer, Tropic of Capricorn, Antarctic Circle, and Arctic Circle.
• The average linear distance of a degree of latitude is 69 miles/111 kilometres. However, the distance is slightly larger at the poles (69.407 miles) than at the Equator (68.704 miles).
• The Latitude of a place may also be determined with the help of a Pole Star.

Learn more about the Earth's Inclination!

Important Parallels of Latitude

Parallels of latitude are imaginary horizontal lines that circle the Earth parallel to the equator. They are crucial for understanding Earth's geography, climate, and the positioning of various regions. Among these, several key parallels stand out due to their geographical and climatic significance.

Equator

The Equator at 0° latitude, divides the Earth into the Northern and Southern Hemispheres. It is the longest latitude line and is significant for receiving direct sunlight throughout the year, leading to a consistent and warm tropical climate.

Tropic of Cancer

The Tropic of Cancer at approximately 23.5° north latitude, marks the northernmost point where the sun is directly overhead during the summer solstice in June. This line demarcates the boundary of the Earth's tropical zone in the northern hemisphere.

Tropic of Capricorn

Similarly, the Tropic of Capricorn at 23.5° south latitude marks the southernmost point of direct overhead sunlight during the December solstice. It defines the southern boundary of the tropical zone.

Arctic Circle

Further north, the Arctic Circle, at about 66.5° north latitude, represents the boundary above which, for at least one day a year, there is a continuous period of daylight (midnight sun) or darkness (polar night).

Antarctic Circle

The Antarctic Circle, located at around 66.5° south latitude, serves a similar purpose in the Southern Hemisphere, encompassing regions that experience at least one day of 24-hour sunlight or darkness each year.

These parallels are essential not just for geographical orientation but also for understanding global climate patterns, as they help define the boundaries of various climatic zones.

Read the article on the Pressure belts of the Earth!

Latitudinal Heat Zones

The Earth is divided into several latitudinal heat zones based on the intensity and angle of sunlight received. These zones have a direct impact on the climate and biodiversity of the regions within them.

Torrid Zone

The Torrid Zone, or the tropics, lies between the Tropic of Cancer and the Tropic of Capricorn. It is characterized by high temperatures throughout the year due to direct sunlight. This zone includes tropical rainforests, savannas, and deserts, witnessing minimal seasonal temperature variation.

Temperate Zone

The Temperate Zones are situated between the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere, and between the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere. These zones experience moderate temperatures with distinct seasonal changes, supporting a variety of ecosystems such as deciduous forests, grasslands, and temperate rainforests.

Frigid Zones

The Frigid Zones, or polar regions, are found within the Arctic and Antarctic Circles. These zones are marked by extreme cold, long periods of darkness or light, and harsh climatic conditions. The polar environments include tundra and ice cap regions, which are sparsely populated by deeply adapted fauna and flora.

Understanding these latitudinal heat zones is crucial for environmental studies, climate science, and for planning human activities such as agriculture, habitation, and tourism.

Northern and Southern hemispheres

The Earth is divided into two halves: the Northern Hemisphere and the Southern Hemisphere. Latitudes tell us how far a place is north or south of the equator. Latitudes are measured in degrees and minutes. They can range from +90 degrees (90 degrees north) to -90 degrees (90 degrees south). The equator is the imaginary line that divides the Earth into the Northern and Southern Hemispheres. Any place north of the equator is in the Northern Hemisphere. Any place south of the equator is in the Southern Hemisphere.

Latitudes are also denoted by positive or negative signs. This indicates whether a place is north or south of the equator. Latitudes north of the equator are denoted by positive values. Latitudes south of the equator are denoted by negative values. For example, the Tropic of Cancer is located at 23 degrees 26 minutes north. The Tropic of Capricorn is located at 23 degrees 26 minutes south.

The Arctic Circle and Antarctic Circle are imaginary lines that mark the boundaries of the Arctic and Antarctic regions, respectively. The Arctic Circle is located at 66 degrees 34 minutes north. The Antarctic Circle is located at 66 degrees 34 minutes south.

Learn more about the Earth And The Solar System!

About Longitude

Longitude is the angular distance of a place measured in degrees along the equator east or west of the Prime Meridian. Longitudes are locations of any place east or west of the Prime Meridian. Unlike the Latitudes, which vary in length, Longitudes are equal in length.

• Unlike latitudes, Longitudes are not parallel to each other. They converge at the two poles.
• Unlike in the case of latitudes, longitude can be taken as the basis for numbering longitudes. The Prime Meridian is taken as 0𝆩 to number the longitudes.
• The portion of the earth east of the Prime Meridian is referred to as the Eastern Hemisphere, and the portion west of the Prime Meridian is called the Western Hemisphere.
• They are numbered 0𝆩 to 180𝆩 east or west of the prime meridian.
• The longitudes intersect with the Equator at right angles.
• Lines of Longitude are referred to as Meridians of Longitude since any place on the same longitude would experience midday/noon at the same time.
• The Longitudes divide the Earth into two parts, i.e., the Eastern Hemisphere and the Western Hemisphere.
• The linear distance of a degree of longitude is maximum at the Equator (69.172 miles) since the difference between two longitudes is maximum at the Equator. It is minimal at the Poles as the Longitudes converge at the poles.

Prime Meridian

The prime meridian is a special line that helps us measure places on Earth. It is like a zero point for measuring how far east or west a place is. The prime meridian runs through Greenwich, England, and it has a longitude of 0 degrees. The opposite of the prime meridian is called the antemeridian, and it is located 180 degrees away from the prime meridian.

Eastern and Western hemispheres

The prime meridian divides Earth into two halves: the eastern and western hemispheres. Longitudes tell us how far a place is east or west of the prime meridian. Similar to latitudes, longitudes are measured in degrees and minutes, sometimes in seconds. A longitude is created by drawing two lines:

• A line from the Earth's center to where the equator intersects the prime meridian
• A line from the Earth's center to any point on the equator

All longitudes are measured based on the angle they make with the center of Earth at the intersection of the equator and the prime meridian.

Learn more about the Structure Of Earth!

Longitude and Time

• The best way to calculate time is by observing the movement of the sun, moon, and other celestial objects.
• The rotation of the Earth is a method of measuring time at a place.
• The Earth completes one rotation on its axis in 24 hours. Hence, it passes through 15𝆩 in an hour.
• As we move every 15𝆩 eastwards, local time is advanced by an hour. Alternatively, if we move westwards, time is reduced by an hour.
• By this, we can conclude that places east of Greenwich experience sunrays earlier and hence gain time. Similarly, areas west of Greenwich see the sun’s rays later and hence lose time.

Standard Time and Time Zones

Timekeeping on Earth is organized through standard time and time zones, which are necessary for synchronized global functioning in various activities, from business operations to transportation and communications.

Standard Time is the uniform time established within a region by law or general usage. It is based on the mean solar time at a central meridian of the time zone. Time Zones help in managing time differences that arise due to Earth’s rotation. The globe is divided into 24 primary time zones, each typically spanning 15 degrees of longitude, corresponding to one hour of the Earth's 24-hour day.

• The Greenwich Mean Time (GMT), centred on the Prime Meridian (0° longitude), is used as the starting reference point for time zones.
• Coordinated Universal Time (UTC) has largely replaced GMT for international timekeeping, though both are closely aligned.
• From here, time zones extend east and west, adjusting by one hour for each 15° of longitude. Key time zones include:
  • Eastern Standard Time (EST): UTC-5 (UTC-4 during daylight saving time)
  • Central Standard Time (CST): UTC-6 (UTC-5 during daylight saving time)
  • Mountain Standard Time (MST): UTC-7 (UTC-6 during daylight saving time)
  • Pacific Standard Time (PST): UTC-8 (UTC-7 during daylight saving time)
  • Indian Standard Time (IST): UTC+5:30
  • China Standard Time (CST): UTC+8
  • Japan Standard Time (JST): UTC+9
  • Australian Eastern Standard Time (AEST): UTC+10

• The International Date Line, an imaginary line roughly along the 180° meridian, marks the place where each new day begins. Crossing this line shifts the calendar date by one day.

Countries and regions sometimes adopt non-standard time zones to better match local conditions, such as daylight saving adjustments, economic convenience, or political reasons.

Learn more about the Heat Budget of Earth!

Difference Between Latitude and Longitude

Difference Between Latitude and Longitude
Latitudes	Longitudes
Latitudes measure the north-south distance on the Earth's surface.	Longitudes measure the east-west distance on the Earth's surface.
They run parallel to the equator.	They are lines that connect the North and South Poles.
The Equator is the starting point with a latitude of 0°.	The Prime Meridian (located in Greenwich, London) is the starting point with a longitude of 0°.
Latitudes are measured in degrees, ranging from 0° at the Equator to 90° at the poles.	Longitudes are also measured in degrees, ranging from 0° to 180° east or west of the Prime Meridian.
Latitudes help divide the world into different climate zones.	Longitudes help determine time zones around the world.

Learn more about the origin and evolution of the earth's crust!

Reading Latitude and Longitude

Every location on Earth has a unique address that uses latitude and longitude to tell us exactly where it is. Latitudes are like street names that run east-west. Longitudes are like house numbers that run north-south. The equator is like the main street in the middle. The prime meridian is like the most important house number.

• For example, Oslo, Norway, is located at 59 degrees 57 minutes north and 10 degrees 45 minutes east. This means that Oslo is 59 degrees and 57 minutes north of the equator and 10 degrees and 45 minutes east of the prime meridian.
• Another example is Montreal, Canada, which is located at 45 degrees 30 minutes north and 73 degrees 34 minutes west. This means that Montreal is 45 degrees and 30 minutes north of the equator and 73 degrees and 34 minutes west of the prime meridian.

So, by knowing the latitude and longitude of a place, we can pinpoint its exact location on Earth.

Learn more about the Climate of India!

Key Takeaways for UPSC Aspirants Definition and Purpose: Latitude and longitude are a coordinate system used to locate points on Earth's surface, essential for navigation, mapping, and geolocation services. Latitude: Lines of latitude, also known as parallels, run east-west and measure the distance north or south of the equator, which is 0° latitude. The poles are at 90° north and south latitude. Longitude: Lines of longitude, or meridians, run from the North Pole to the South Pole and measure the distance east or west of the Prime Meridian, which is 0° longitude and passes through Greenwich, England. Degrees, Minutes, and Seconds: Coordinates are typically given in degrees (°), minutes ('), and seconds ("). For finer precision, decimal degrees can also be used. Hemispheres: The globe is divided into the Northern and Southern Hemispheres by the equator, and the Eastern and Western Hemispheres by the Prime Meridian and the 180° meridian. Global Positioning System (GPS): Latitude and longitude are the foundation of the GPS, which uses satellite signals to provide precise location data for navigation and mapping. Historical Context: The system was refined over centuries, with significant contributions from explorers, astronomers, and cartographers, and was crucial for sea navigation before modern technology. Applications: Beyond navigation, latitude and longitude are used in fields such as meteorology, aviation, geology, and environmental science to track weather patterns, flight paths, tectonic activity, and ecosystem changes. Equator and Prime Meridian as Reference Points: The equator and Prime Meridian are the reference points for latitude and longitude, holding significant geographical importance and being the basis for dividing the Earth into specific coordinates. Conversion and Accuracy: Understanding how to convert between different formats (degrees, decimal minutes, and seconds) and ensuring accuracy is vital for precise geolocation, crucial for scientific research and everyday applications like navigation apps.

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