Latitudes and Important Parallels
Geography › Earth, Latitudes, Longitudes and Motions · Topic 1.1
Latitude is the angular distance of a place north or south of the equator, measured in degrees from the centre of the Earth. Lines joining places of equal latitude are called parallels, and the equator, the Tropics, the Arctic Circle and the Antarctic Circle divide the Earth into the torrid, temperate and frigid heat zones.
6 min read · UPSC Prelims · Geography · Earth, Latitudes, Longitudes and Motions
At a Glance
- Meaning Angular distance north or south of the equator
- Zero line The equator (0 degrees)
- Range 0 to 90 degrees north and south
- Important parallels Equator, two Tropics and two Polar Circles
- Heat zones Torrid, temperate and frigid
- Exam link UPSC Prelims, Geography: Earth, Latitudes, Longitudes and Motions
Where Does It Fit?
This is the first topic of the category on the Earth, latitudes, longitudes and motions. It sets up the grid of imaginary lines used to fix any place on the globe. The next topic covers longitudes, meridians and time zones. Next topic: Longitudes, Meridians and Time Zones.
What Is Latitude?
In short: latitude tells how far a place lies north or south of the equator.
Latitudes and longitudes are imaginary lines that make a coordinate system. They are used to fix the location of any place on the Earth; for example, New Delhi lies at about 28 degrees north latitude and 77 degrees east longitude. Latitude is the angular distance of a place north or south of the equator, measured in degrees from the centre of the Earth. The equator is the zero line, so latitude runs from 0 degrees at the equator to 90 degrees at each pole. Places north of the equator carry the suffix N and places south of it the suffix S. Lines joining all places with the same latitude are called parallels of latitude, because they run parallel to the equator and never meet. The equator is the longest parallel, and parallels become shorter towards the poles, where they shrink to points.
How Long Is a Degree of Latitude?
Because the Earth is slightly flattened at the poles, a degree of latitude is not exactly the same length everywhere. At the equator one degree of latitude is about 110.57 km, at 45 degrees it is about 111.13 km, and at the poles it is about 111.7 km. For convenience an average of about 111 km is used, which is why distances north and south can be found quickly by counting degrees.
| Latitude | Length of one degree |
|---|---|
| Equator (0 degrees) | About 110.57 km |
| 45 degrees | About 111.13 km |
| Poles (90 degrees) | About 111.7 km |
Which Are the Important Parallels of Latitude?
Besides the equator (0 degrees), the North Pole (90 degrees N) and the South Pole (90 degrees S), four parallels are important. Each marks a change in how the Sun’s rays strike the Earth through the year.
| Parallel | Position | Why it matters |
|---|---|---|
| Tropic of Cancer | 23.5 degrees N | Northernmost latitude where the midday Sun can be directly overhead, on 21 June |
| Tropic of Capricorn | 23.5 degrees S | Southernmost latitude where the midday Sun can be directly overhead, on 22 December |
| Arctic Circle | 66.5 degrees N | Boundary of the zone where the Sun does not set at midsummer |
| Antarctic Circle | 66.5 degrees S | Boundary of the zone where the Sun does not set at midsummer in the south |
The Tropic of Cancer passes through eight Indian states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. It divides India almost into two halves, with the northern part in the subtropical zone and the southern part in the tropical zone.
What Are the Heat Zones of the Earth?
The Earth’s parallels divide it into three heat zones, according to how the midday Sun’s rays reach the surface.
| Zone | Limits | Condition |
|---|---|---|
| Torrid zone | Between the Tropic of Cancer and the Tropic of Capricorn | The midday Sun is exactly overhead at least once a year on every latitude here, so it gets the maximum heat |
| Temperate zones | From each Tropic to the nearest Polar Circle | The Sun is never overhead and the angle of its rays decreases poleward, so temperatures are moderate |
| Frigid zones | Beyond the Arctic and Antarctic Circles | The Sun does not rise much above the horizon, so its rays are always slanting and it is very cold |
Temperature falls as one moves from the equator towards the poles because the Earth is a sphere: the equator receives direct sunlight, while the rays become oblique towards the poles and the energy received per unit area decreases. This is a key idea behind the topics on temperature distribution later in the subject.
What Is the Latitudinal Extent of India?
The mainland of India extends from about 8 degrees 4 minutes N to 37 degrees 6 minutes N latitude. The southernmost point of the country, Indira Point in the Great Nicobar Island, lies at about 6 degrees 45 minutes N. The latitudinal extent is therefore about 29 degrees from Kanyakumari to the north of Kashmir, and the distance from north to south on the mainland is about 3,200 km. Because the Tropic of Cancer cuts through the country, India has both tropical and subtropical regions, which helps explain the variety of its climate. The comparison with longitude and time is in Longitudes, Meridians and Time Zones.
As an analytical point, latitude is the first and most direct control on climate, because it decides how much solar energy a place receives; later controls such as altitude, ocean currents and distance from the sea modify this basic pattern.
Why Is This Topic Important?
- Basis of climate zones Latitude controls heat
- Frequent Prelims theme Tropics and Circles
- Map skills Locating places
What Came Next?
The next topic describes longitudes, meridians and the time zones of the world. Next topic: Longitudes, Meridians and Time Zones.
Key People and Terms
- Parallel Line of equal latitude
- Equator Zero degree latitude, longest parallel
- Torrid zone Between the Tropics
- Temperate zone Between a Tropic and a Polar Circle
- Frigid zone Beyond a Polar Circle
- Indira Point Southernmost point of India
Exam Corner
Points to Remember
- Tropics lie at 23.5 degrees and Polar Circles at 66.5 degrees.
- The equator is the longest parallel.
- One degree of latitude is about 111 km.
- The Tropic of Cancer crosses eight Indian states.
- The torrid zone gets the Sun overhead at least once a year.
Do Not Confuse With
- Parallels and meridians Parallels run east-west; meridians run pole to pole
- The North Pole and a latitude The pole is a point at 90 degrees N, while a latitude is a circle
- Tropics and Polar Circles 23.5 degrees versus 66.5 degrees
Memory Hook
Tropics at 23 and a half; Circles at 66 and a half; torrid between the two Tropics.
Mains Angle
Questions ask why climate differs with latitude. These points add depth.
- Solar energy Direct rays at the equator
- Zones Torrid, temperate and frigid
- India Tropic of Cancer divides the country
A Question You May Face
An original practice question, not a past paper question.
“Explain how latitude influences the distribution of temperature on the Earth.”
How to Answer
- Define Latitude and parallels.
- Mechanism Angle of the Sun’s rays.
- Zones Heat zones.
- Example India and the Tropic of Cancer.
GS Relevance
Frequently Asked Questions
What is latitude?
Latitude is the angular distance of a place north or south of the equator, measured in degrees from the centre of the Earth. It ranges from 0 degrees at the equator to 90 degrees at each pole, and lines of equal latitude are called parallels.
Which are the important parallels of latitude?
Besides the equator at 0 degrees and the poles at 90 degrees, the important parallels are the Tropic of Cancer at 23.5 degrees N, the Tropic of Capricorn at 23.5 degrees S, the Arctic Circle at 66.5 degrees N and the Antarctic Circle at 66.5 degrees S.
What is the torrid zone?
The torrid zone lies between the Tropic of Cancer and the Tropic of Capricorn. The midday Sun is exactly overhead at least once a year on every latitude in this belt, so it receives the maximum heat and has the highest average temperatures on Earth.
Why does temperature fall from the equator towards the poles?
Temperature falls poleward because the Earth is a sphere. The equator receives direct sunlight, while the Sun's rays become more slanting towards the poles, so the energy received per unit area decreases and the surface is cooler.
Through which Indian states does the Tropic of Cancer pass?
The Tropic of Cancer passes through eight Indian states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. It divides India into a northern subtropical part and a southern tropical part, which gives the country a wide range of climates.
PYQ Practice — Statement Analysis
1 The equator is the longest parallel of latitude.
Parallels shorten towards the poles.
2 The Tropic of Capricorn lies at 23.5 degrees N.
It lies at 23.5 degrees S.
3 The Sun is never exactly overhead in the temperate zones.
Only the torrid zone gets it overhead.
4 One degree of latitude is exactly the same length everywhere.
It varies slightly because the Earth is flattened at the poles.
Related Topics
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