Which one among the following cities never get the vertical rays of the Sun all through the year ?

1. Earth’s Tilt and the Mechanics of Insolation (basic)

To understand why the sun feels different in Northern India compared to Southern India, we must start with the Earth's axial tilt. The Earth does not orbit the sun in an "upright" position; instead, its axis is tilted at an angle of 23.5° from the perpendicular to its orbital plane. This tilt is the primary reason for the variation in the intensity of sunlight (insolation) and the change of seasons Science-Class VII NCERT, Earth, Moon, and the Sun, p.177.

Because the Earth maintains this fixed tilt while revolving around the Sun, the subsolar point—the specific spot on Earth where the sun’s rays hit vertically at a 90° angle—migrates throughout the year. This migration is limited to a specific belt called the Torrid Zone. The boundaries of this zone are defined by the tilt itself:

• Tropic of Cancer (23.5° N): The northernmost limit where the sun can ever be directly overhead (usually on June 21st).
• Tropic of Capricorn (23.5° S): The southernmost limit where the sun can be directly overhead (usually on December 22nd).

Within this belt, every location experiences the mid-day sun exactly overhead at least once a year (and twice a year for most spots). Outside this belt, in the temperate and frigid zones, the sun's rays are always slanted. The mid-day sun will never reach the zenith (the point directly above your head) Physical Geography by PMF IAS, Latitudes and Longitudes, p.242. This explains why a city like Chennai (13° N) or Kolkata (22.6° N) sees the sun directly overhead twice a year, while a city like Srinagar (34° N), which lies well north of the Tropic of Cancer, never does Physical Geography by PMF IAS, Latitudes and Longitudes, p.240.

Sources: Science-Class VII NCERT, Earth, Moon, and the Sun, p.177; Physical Geography by PMF IAS, Latitudes and Longitudes, p.240; Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; Certificate Physical and Human Geography, GC Leong, The Earth's Crust, p.15

2. The Three Heat Zones of the Earth (basic)

To understand why different parts of the Earth have different climates, we must look at the Earth's shape. Because the Earth is a sphere, the Sun's rays do not strike the surface at the same angle everywhere. This creates an unequal distribution of solar energy (insolation), dividing the Earth into three distinct Heat Zones. The primary factor determining these zones is the latitude, which dictates how high the Sun rises in the sky and how concentrated its heat is on the ground.

The first and hottest zone is the Torrid Zone. This region lies between the Tropic of Cancer (23.5° N) and the Tropic of Capricorn (23.5° S). In this belt, the mid-day Sun is exactly overhead at least once a year on every latitude Physical Geography by PMF IAS, Latitudes and Longitudes, p.242. Because the Sun's rays fall vertically here, they cover a small area with high intensity, making this the warmest part of the planet. This zone is characterized by high humidity and significant rainfall, especially near the Equator Physical Geography by PMF IAS, Climatic Regions, p.423.

As we move toward the poles, the angle of the Sun's rays becomes increasingly slanted. This leads us to the Temperate Zones, located between the Tropics and the Arctic Circle (66.5° N) in the north, and the Antarctic Circle (66.5° S) in the south Physical Geography by PMF IAS, Latitudes and Longitudes, p.240. In these areas, the mid-day Sun is never directly overhead. Because the rays are slanted, they spread over a larger area and lose intensity, resulting in moderate temperatures. Finally, the Frigid Zones exist beyond the Arctic and Antarctic circles up to the poles. Here, the Sun barely rises above the horizon, and its rays are so slanted that they provide very little heat, resulting in a permanent cold environment Physical Geography by PMF IAS, Latitudes and Longitudes, p.242.

Heat Zone	Latitudinal Boundaries	Solar Characteristic
Torrid	23.5° N to 23.5° S	Sun shines vertically overhead at least once a year.
Temperate	23.5° to 66.5° (N & S)	Sun is never overhead; rays are always slanted.
Frigid	66.5° to 90° (N & S)	Sun rays are extremely slanted; very little heat.

Sources: Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; Physical Geography by PMF IAS, Latitudes and Longitudes, p.240; Physical Geography by PMF IAS, Climatic Regions, p.423

3. The Solstices and the Apparent Movement of the Sun (intermediate)

To understand India’s climate and geography, we must first master the apparent movement of the Sun. While we say the Sun "moves" north or south, this is actually an optical illusion caused by the Earth’s axial tilt of 23.5° as it revolves around the Sun. This tilt ensures that the Sun’s vertical (90°) rays are not fixed on the Equator but migrate across a specific latitudinal belt throughout the year. Physical Geography by PMF IAS, Latitudes and Longitudes, p. 242.

The two extreme points of this migration are known as the Solstices. On June 21st (Summer Solstice), the Northern Hemisphere tilts toward the Sun, and the vertical rays strike the Tropic of Cancer (23.5° N). This marks the longest day of the year for us in India. Science-Class VII NCERT, Earth, Moon, and the Sun, p. 179. Conversely, on December 22nd (Winter Solstice), the Sun’s rays fall vertically on the Tropic of Capricorn (23.5° S) in the Southern Hemisphere. On this day, the Northern Hemisphere experiences its shortest day and longest night. Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p. 253.

This movement creates a distinct geographical zone called the Torrid Zone (or the Tropics). Any location within this zone—between 23.5° N and 23.5° S—will experience the midday Sun directly overhead at least twice a year. However, for any region located poleward of the Tropics (further north than 23.5° N or further south than 23.5° S), the Sun’s rays will always be slanted. In these regions, the Sun will never reach the zenith, meaning it is never directly overhead at any time of the year. Physical Geography by PMF IAS, Latitudes and Longitudes, p. 240.

Feature	Summer Solstice (Northern Hemisphere)	Winter Solstice (Northern Hemisphere)
Approximate Date	June 21	December 22
Sun Vertical At	Tropic of Cancer (23.5° N)	Tropic of Capricorn (23.5° S)
NH Day Length	Longest Day, Shortest Night	Shortest Day, Longest Night
Arctic Circle	24 hours of daylight	24 hours of darkness

Sources: Physical Geography by PMF IAS, Latitudes and Longitudes, p.240-242; Science-Class VII NCERT, Earth, Moon, and the Sun, p.179; Physical Geography by PMF IAS, The Motions of The Earth and Their Effects, p.253

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

To understand India’s geography, we must look at the Tropic of Cancer (23.5° N), which acts as a massive imaginary divider cutting through the heart of the country. Stretching from the Rann of Kuchchh in the west to Mizoram in the east, this latitude divides India almost equally into two distinct climatic zones CONTEMPORARY INDIA-I, Climate, p.27. The region lying south of this line is the Tropical Zone, while the region to the north is the Sub-tropical (or warm temperate) zone. This division is the reason why India is often described as having a dual personality: the South remains warm year-round, while the North experiences sharp seasonal contrasts INDIA PHYSICAL ENVIRONMENT, Climate, p.29.

One of the most fascinating implications of this latitudinal position involves the overhead sun. Because the Earth is tilted, the sun's vertical rays only migrate between the Tropic of Cancer and the Tropic of Capricorn. In India, any location south of the Tropic of Cancer (like Mumbai, Chennai, or Bengaluru) will experience the mid-day sun exactly overhead twice a year. However, for any city north of this line—such as Delhi, Jaipur, or Srinagar—the sun's rays are always slanted, and the sun will never be directly overhead, not even on the longest day of the year INDIA PHYSICAL ENVIRONMENT, Climate, p.29.

The Tropic of Cancer passes through eight Indian states. Remembering them in order from West to East is a classic requirement for the UPSC. These states are: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram CONTEMPORARY INDIA-I, India Size and Location, p.6.

Feature	South of Tropic of Cancer (Tropical)	North of Tropic of Cancer (Sub-tropical)
Solar Radiation	Receives vertical (overhead) rays twice a year.	Sun is never directly overhead; rays are always slanted.
Temperature Range	Small daily and annual range (stable temperatures).	High daily and annual range (extreme summers/winters).

Sources: CONTEMPORARY INDIA-I, Climate, p.27; INDIA PHYSICAL ENVIRONMENT, Climate, p.29; CONTEMPORARY INDIA-I, India Size and Location, p.6

5. Latitudinal Impact on Day Length and Climate in India (exam-level)

To understand how India experiences such diverse weather, we must look at its latitudinal extent. The Tropic of Cancer (23.5° N) acts as a fundamental climatic divide, slicing the country almost in half. The region south of this line falls within the Tropical Zone (Torrid Zone), while the region to the north lies in the Sub-tropical and Temperate Zone. Because the Sun’s vertical rays only migrate between the two Tropics, cities like Chennai, Mumbai, and Kolkata experience the mid-day sun exactly overhead twice a year. In contrast, for a city like Srinagar, the sun’s rays are always slanted, and it never experiences the vertical sun INDIA PHYSICAL ENVIRONMENT, Geography Class XI, Climate, p.29.

This latitudinal position directly dictates the duration of day and night. As you move from the Equator toward the Poles, the variation in day length increases. In Kanyakumari (approx. 8° N), being close to the Equator, the difference between the longest and shortest day is hardly 45 minutes. However, as you travel north to Kashmir (approx. 35° N), this difference becomes very pronounced, often exceeding several hours between summer and winter CONTEMPORARY INDIA-I, Geography Class IX, India Size and Location, p.2. This is why a winter evening feels much "shorter" in North India than in the South.

Furthermore, latitude governs the Annual Range of Temperature. The tropical southern half, surrounded by oceans, enjoys a maritime climate with high temperatures throughout the year and very little variation between seasons. The northern half, however, is continental and removed from the equator's moderating influence. This results in extreme climate: blistering summers where Rajasthan might touch 50°C, and bone-chilling winters where places like Drass or Srinagar drop well below freezing CONTEMPORARY INDIA-I, Geography Class IX, Climate, p.26.

Feature	South India (Tropical)	North India (Sub-tropical)
Solar Rays	Vertical rays twice a year	Always slanted rays
Day/Night Variation	Negligible (Hardly felt)	Significant variation
Temperature Range	Low annual/daily range	High (Extreme) annual range

Sources: INDIA PHYSICAL ENVIRONMENT, Geography Class XI, Climate, p.29; CONTEMPORARY INDIA-I, Geography Class IX, India Size and Location, p.2; CONTEMPORARY INDIA-I, Geography Class IX, Climate, p.26

6. Decoding the 'Vertical Rays' Phenomenon (exam-level)

To understand why some places in India experience the sun directly overhead while others never do, we must start with the Earth's axial tilt. The Earth is tilted at an angle of 23.5° from its vertical axis. Because of this tilt and the Earth's revolution around the Sun, the subsolar point (the place where the Sun's rays hit the surface at a perfect 90° angle) migrates throughout the year. This migration is strictly limited to the region 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, and it is the only part of the planet where the mid-day sun can be exactly overhead at least once a year PMF IAS, Latitudes and Longitudes, p.242.

There are two scientific reasons why vertical rays feel significantly hotter than slanted rays. First, concentration of energy: a vertical beam of light hits a small, concentrated area, whereas slanted rays spread the same amount of energy over a much larger surface area, diluting the heat. Second, atmospheric depth: slanted rays must travel a longer distance through the Earth's atmosphere. This extra travel time leads to more energy being lost to absorption, scattering, and diffusion by atmospheric particles before the light even reaches the ground NCERT Class XI, Solar Radiation, Heat Balance and Temperature, p.68.

Applying this to Indian Geography provides a clear divide. The Tropic of Cancer passes through the middle of India. Consequently, cities located south of this line—such as Chennai (13° N), Mumbai (19° N), and Kolkata (22.6° N)—experience the Sun being vertically overhead twice every year as the subsolar point moves north toward the Tropic of Cancer and then retreats south toward the Equator. However, for any location north of the Tropic of Cancer, such as Delhi or Srinagar (34° N), the mid-day sun's rays are always slanted. In these northern cities, the Sun will never reach the zenith (the point directly above one's head), regardless of the season GC Leong, The Earth's Crust, p.7.

Sources: Physical Geography by PMF IAS, Latitudes and Longitudes, p.242; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Solar Radiation, Heat Balance and Temperature, p.68; Certificate Physical and Human Geography, GC Leong, The Earth's Crust, p.7

7. Solving the Original PYQ (exam-level)

This question is a classic application of the apparent movement of the Sun between the Tropics. Having mastered the concepts of the Earth's tilt and the Torrid Zone, you know that the mid-day Sun is only ever exactly overhead on latitudes ranging from the Tropic of Cancer (23.5° N) to the Tropic of Capricorn (23.5° S). As explained in FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), beyond these parallels, the Sun’s rays are always slanted because the subsolar point never migrates into the Temperate or Frigid zones. To solve this, you must simply determine which city lies outside this "tropical belt."

Looking at the geography of India, Chennai (13° N), Mumbai (19° N), and Kolkata (22.6° N) all lie south of the Tropic of Cancer. Therefore, they experience vertical rays twice a year as the Sun moves north toward the solstice and south toward the equinox. However, Srinagar is located at approximately 34° N, which is significantly north of the Tropic of Cancer. Because Srinagar is in the North Temperate Zone, the mid-day Sun will always appear at an angle and never reach the zenith (90°). This makes (D) Srinagar the only logical answer.

The UPSC often uses Kolkata as a distractor because of its proximity to the Tropic of Cancer, tempting students to think it might be "too far north." Remember the rule: if the latitude is even slightly less than 23.5°, it will receive vertical rays. As noted in Physical Geography by PMF IAS, any location within the Torrid Zone receives vertical rays twice a year—once during the Sun's northward journey and once during its southward journey. Srinagar's high latitude ensures it is forever excluded from this phenomenon.

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