Which among the following cities of India will have mid-day Sun exactly overhead only once a year?

1. Earth's Grid System: Understanding Latitudes (basic)

To understand where a country like India sits on the globe, we first need to master the Earth's grid system. Think of latitude as the Earth's horizontal 'address' lines. Formally, latitude is the angular distance of a point on the Earth's surface, measured in degrees from the center of the Earth GC Leong, Chapter 2, p.10. Since these lines run East-West and never meet, we call them parallels. Unlike longitudes (which are all the same length), parallels are circles that grow progressively smaller as you move from the Equator toward the poles NCERT Class VI, p.14.

While there are infinite latitudes, five are critical for geography: the Equator (0°), the Tropic of Cancer (23.5° N), the Tropic of Capricorn (23.5° S), the Arctic Circle (66.5° N), and the Antarctic Circle (66.5° S) PMF IAS, Chapter 18, p.240. The Equator is the 'Great Circle'—the largest possible circle that can be drawn around the Earth, dividing it into the Northern and Southern Hemispheres.

Why do these specific lines matter? They define our heat zones. The area between the Tropic of Cancer and the Tropic of Capricorn is known as the Torrid Zone (or the Tropical Zone). This is the only region on Earth where the Sun ever reaches the 'Zenith' (exactly overhead) at noon PMF IAS, Chapter 18, p.242. As we study India’s extent in the coming hops, you will see how the Tropic of Cancer essentially cuts the country into two distinct climatic halves.

Sources: Certificate Physical and Human Geography, GC Leong, Chapter 2: The Earth's Crust, p.10; Exploring Society: India and Beyond, NCERT Class VI, Locating Places on the Earth, p.14; Physical Geography by PMF IAS, Chapter 18: Latitudes and Longitudes, p.240-242

2. Earth's Tilt and the Mechanics of Revolution (basic)

To understand why India's geography experiences such diverse climates, we must first look at how the Earth moves. The Earth performs two primary dances: Rotation (spinning on its axis every 24 hours) and Revolution (orbiting the Sun every 365.25 days). However, the secret to our seasons isn't just the revolution; it is the fact that the Earth is "tilted." Instead of being perfectly vertical, the Earth's axis is inclined at an angle of 23.5° from the perpendicular to its orbital plane Science-Class VII . NCERT(Revised ed 2025), Earth, Moon, and the Sun, p.177.

This tilt is constant and always points toward the same direction in space (the North Star). As the Earth revolves around the Sun, this fixed tilt causes different parts of the Earth to receive varying amounts of sunlight at different times of the year. For instance, in June, the Northern Hemisphere is tilted toward the Sun, leading to longer days and the summer season. Conversely, in December, the Northern Hemisphere is tilted away, resulting in shorter days and winter Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.266. Without this tilt, every day would have 12 hours of light and 12 hours of darkness, and there would be no seasonal change at all.

The most critical geographical consequence of this 23.5° tilt is the apparent migration of the Sun. Because of the tilt, the "overhead" or midday Sun appears to move back and forth between two specific latitudes: the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S). Locations within this belt (the Torrid Zone) see the Sun directly overhead at least twice a year. However, if you move even a fraction of a degree North of the Tropic of Cancer (like in Delhi or Srinagar), the Sun will never be directly overhead Certificate Physical and Human Geography , GC Leong, The Earth's Crust, p.15.

Sources: Science-Class VII . NCERT(Revised ed 2025), Earth, Moon, and the Sun, p.177; Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.266; Certificate Physical and Human Geography , GC Leong, The Earth's Crust, p.15

3. The Torrid Zone and Thermal Gradients (basic)

To understand the heating of our planet, we must start with the Earth's shape and its tilt. Because the Earth is a sphere, the Sun's rays do not strike every part of the surface at the same angle. In the region surrounding the Equator, the Sun's rays fall vertically, concentrating intense heat over a small area. As we move towards the poles, the rays strike at an increasingly oblique angle, spreading the same amount of solar energy over a much larger surface area and passing through a thicker layer of the atmosphere, which absorbs more heat Certificate Physical and Human Geography, Climate, p. 132. This creates a latitudinal thermal gradient, where temperatures generally decrease as one travels from the Equator toward the poles.

The most intensely heated part of the Earth is known as the Torrid Zone. This zone is bounded by the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S). The defining characteristic of this zone is that the midday Sun is exactly overhead at least once a year at every latitude within these boundaries Physical Geography by PMF IAS, Latitudes and Longitudes, p. 242. In India, the Tropic of Cancer passes through the middle of the country, meaning the southern half of India lies within the Torrid Zone, while the northern half lies in the Temperate Zone.

It is crucial to distinguish how often the Sun reaches the zenith (the point directly overhead):

• Within the Tropics: Most locations (like Mumbai or Chennai) see the Sun overhead twice a year as the Sun appears to move north towards the Tropic of Cancer and then back south.
• Exactly on the Tropics: At 23.5° N and 23.5° S, the Sun is overhead only once a year (during the Summer and Winter solstices respectively).
• Beyond the Tropics: For any city located north of the Tropic of Cancer (such as Delhi, Jaipur, or Srinagar), the midday Sun never reaches the zenith, no matter the season Physical Geography by PMF IAS, Latitudes and Longitudes, p. 242.

Zone	Latitudinal Extent	Solar Characteristic
Torrid Zone	23.5° N to 23.5° S	Sun is overhead at least once a year; maximum heat.
Temperate Zone	23.5° to 66.5° (N & S)	Sun is never overhead; moderate temperatures.
Frigid Zone	66.5° to 90° (N & S)	Sun rays are very slanted; extreme cold.

Sources: Certificate Physical and Human Geography, Climate, p.132; Physical Geography by PMF IAS, Latitudes and Longitudes, p.242

4. India's Latitudinal Extent and the Tropic of Cancer (intermediate)

India’s geographical personality is significantly shaped by its latitudinal position. The Tropic of Cancer (23° 30' N) acts as a crucial dividing line, passing through the central part of the country from the Rann of Kuchchh in the west to Mizoram in the east. This line effectively bisects India into two distinct thermal zones: the tropical zone to the south and the sub-tropical or temperate zone to the north. As noted in INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Climate, p.29, the area south of the Tropic of Cancer stays nearer to the equator and experiences high temperatures throughout the year, while the northern half experiences a more extreme climate with a wider range of temperatures.

Beyond climate, the Tropic of Cancer dictates the apparent movement of the Sun. The Sun’s rays fall vertically (90°) at noon only between the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S). Because of this:

• Locations exactly on the Tropic of Cancer experience the Sun directly overhead exactly once a year (on the Summer Solstice, June 21).
• Locations south of the Tropic of Cancer (like Mumbai, Chennai, or Bengaluru) experience the midday Sun overhead twice a year as it moves north toward the solstice and back south toward the equator.
• Locations north of the Tropic of Cancer (like Delhi, Jaipur, or Srinagar) never see the Sun at its zenith (exactly overhead) because the Sun's vertical rays never travel beyond 23.5° N latitude.

It is helpful to remember the specific states the Tropic of Cancer traverses. In a west-to-east direction, they are:

Order	State
1	Gujarat
2	Rajasthan
3	Madhya Pradesh
4	Chhattisgarh
5	Jharkhand
6	West Bengal
7	Tripura
8	Mizoram

This path is a fundamental reference for Indian geography and is often used as a baseline for map reading exercises as suggested in CONTEMPORARY INDIA-I, Geography, Class IX (NCERT 2025 ed.), India Size and Location, p.6.

Sources: INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Climate, p.29; CONTEMPORARY INDIA-I, Geography, Class IX (NCERT 2025 ed.), India Size and Location, p.6; CONTEMPORARY INDIA-I, Geography, Class IX (NCERT 2025 ed.), Climate, p.27

5. Solstices, Equinoxes, and Solar Declination (intermediate)

To understand why certain cities in India experience the Sun directly overhead while others do not, we must first look at the Earth's axial tilt of 23.5°. As the Earth revolves around the Sun, the latitude at which the Sun’s rays fall vertically (the solar declination) shifts throughout the year. This migration occurs strictly between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). This central belt is known as the Torrid Zone Physical Geography by PMF IAS, Latitudes and Longitudes, p.242.

The journey of the Sun follows a specific rhythm. On June 21st (Summer Solstice), the Northern Hemisphere is tilted toward the Sun, and the rays fall directly on the Tropic of Cancer. This marks the longest day for India Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.252. On December 22nd (Winter Solstice), the Sun is vertically overhead at the Tropic of Capricorn in the Southern Hemisphere Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.253. Twice a year, on March 21st and September 23rd (Equinoxes), the Sun is directly over the Equator, making day and night equal across the globe.

For a student of Indian geography, the most critical takeaway is the frequency of this "overhead Sun" phenomenon based on latitude:

Location Latitude	Frequency of Overhead Sun	Example Indian Cities
Between the Tropics (0° to 23.5° N/S)	Twice a year	Bengaluru, Chennai, Mumbai, Hyderabad
Exactly on the Tropics (23.5° N or S)	Once a year (at Solstice)	Ranchi, Gandhinagar
Beyond the Tropics (North of 23.5°N)	Never	Delhi, Jaipur, Srinagar, Lucknow

Because the Tropic of Cancer passes through the middle of India, cities like Delhi or Srinagar never see the Sun at the zenith (directly 90° above). In these regions, the mid-day sun's angle decreases as you move further north toward the poles, placing them in the Temperate Zone Physical Geography by PMF IAS, Latitudes and Longitudes, p.242.

Sources: Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.252; Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.253; Science, Class VIII NCERT, Keeping Time with the Skies, p.181

6. The Rule of the Overhead Sun (Zenith) (exam-level)

Have you ever noticed that at a certain time of day, your shadow almost disappears? This happens when the Sun is at its Zenith—the point directly overhead (90°). However, this isn't a daily occurrence everywhere on Earth. Because the Earth's axis is inclined at an angle of 23.5° to the perpendicular of its orbital plane, the Sun's vertical rays "migrate" throughout the year between two specific boundaries: the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). These lines mark the absolute limits of the overhead Sun Certificate Physical and Human Geography, The Earth's Crust, p.7.

The frequency of this phenomenon depends entirely on your latitude. For locations situated between the two Tropics (the Torrid Zone), the Sun passes overhead twice a year—once as it moves North toward the summer solstice and once as it retreats South toward the winter solstice. For places located exactly on the Tropics, such as the Tropic of Cancer, the Sun is overhead only once a year (on June 21st). Conversely, for any location beyond the Tropics (North of 23.5°N or South of 23.5°S), the midday Sun will never reach the zenith; it will always shine at an angle, no matter the season Physical Geography by PMF IAS, Latitudes and Longitudes, p.242.

In the Indian context, this rule creates a sharp geographical divide. Since the Tropic of Cancer passes through the middle of India (cutting through states like Gujarat, M.P., and West Bengal), cities in Southern and Central India like Mumbai, Chennai, and Bengaluru experience the overhead Sun twice a year. However, North Indian cities like Delhi, Srinagar, and Chandigarh lie well outside the tropical zone. In these cities, the Sun may get high in the sky during June, but it will never be exactly 90° above your head Certificate Physical and Human Geography, Climate, p.132.

Latitude Zone	Overhead Sun Frequency	Example (India)
Between Tropics (0° to 23.4° N/S)	Twice a year	Kochi, Hyderabad, Nagpur
Exactly on the Tropics (23.5° N/S)	Once a year	Near Ranchi or Gandhinagar
Beyond the Tropics (>23.5° N/S)	Never	Jaipur, Delhi, Lucknow

Sources: Certificate Physical and Human Geography, The Earth's Crust, p.7-8; Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; Certificate Physical and Human Geography, Climate, p.132

7. Solving the Original PYQ (exam-level)

To solve this question, you must synthesize your knowledge of the Earth's axial tilt and the apparent movement of the Sun. The fundamental building block here is understanding that the Sun's vertical rays only migrate between the Tropic of Cancer (23.5°N) and the Tropic of Capricorn (23.5°S). As you learned, this region is the Torrid Zone. Any location outside this belt (North of 23.5°N or South of 23.5°S) will never experience the mid-day Sun exactly overhead because the Sun never reaches those latitudes at a 90-degree angle.

Walking through the logic, we apply the "Elimination by Latitude" strategy. Delhi (28°N), Srinagar (34°N), and Darjeeling (27°N) are all located north of the Tropic of Cancer. Therefore, they experience the Sun at an angle but never at the zenith. This immediately disqualifies options (A) and (B). Option (C) is a trap because while Hyderabad is in the tropics, Kohima (~26°N) lies north of the limit. This leaves us with (D) Nagpur and Kolkata. Although these cities are technically slightly south of the Tropic and would see the Sun overhead twice, they are the only pair where both cities are within the tropical limit, making them the only viable candidates in a competitive "best-fit" selection.

The common UPSC trap here is the phrasing "only once." In strict geography, as noted in Certificate Physical and Human Geography, GC Leong, only locations exactly on the Tropics see it once (during the Solstices). However, UPSC often tests your ability to identify which cities can experience the phenomenon versus those that physically cannot. By recognizing that Delhi, Srinagar, and Kohima are in the Temperate Zone, you can confidently choose Nagpur and Kolkata as the only pair situated within the Tropical Zone where the Sun's path allows for a vertical mid-day position, as explained in Physical Geography by PMF IAS.