Urban Heat Island (UHI) Effect
Geography
- PYQs7
- Articles1
Background
Essential for understanding urban climate, sustainable urban planning, climate change adaptation strategies, and public health in cities. Relevant for GS1 (Urbanization, Geography), GS3 (Environment).
The Urban Heat Island (UHI) effect is a phenomenon where urban areas experience significantly higher temperatures than surrounding rural areas due to human activities and altered land surfaces. It is a key factor in intensifying heat stress in densely populated regions.
Facts & tables
- Temperature Difference
- Urban areas can be 4 to 5 degrees Celsius warmer than nearby open areas, contributing to discomfort and 'real-feel' temperatures.
- Causes
- Primarily caused by land use and land cover changes, such as the replacement of natural vegetation with heat-absorbing concrete and asphalt.
- Nighttime Heat
- Concrete structures absorb and slowly release heat throughout the day, leading to persistently elevated nighttime temperatures indoors.
- Aggravating Factors
- Denser population and traffic further add to the UHI effect in urban environments.
| Type | Reference |
|---|---|
| Conceptual area | Climate Change Adaptation |
| Conceptual area | Urban Planning |
Prelims angle
Prelims angle: Statement-based questions
Prelims angle: Conceptual understanding
- Urban areas significantly warmer than rural counterparts.
- Caused by land use changes (concrete, asphalt).
- Leads to higher indoor and nighttime temperatures.
- Mitigation: urban greening, cool roofs, sustainable construction.
- Exacerbates heat stress in cities.
| Year | Framing tags |
|---|---|
| 2026 | Multi-statement analysis, Factual recall |
| 2025 | Multi-statement analysis, Conceptual understanding |
| 2024 | Factual recall, Conceptual understanding |
| 2023 | Statement-based questions, Conceptual understanding |
| 2021 | Statement-based questions, Conceptual understanding |
| 2020 | Statement-based questions, Conceptual understanding |
| 2013 | Multi-statement analysis, Conceptual understanding |
Timeline
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Climate Change Adaptation
Conceptual area
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Urban Planning
Conceptual area
-
Prelims 2013
Multi-statement analysis, Conceptual understanding
-
Prelims 2020
Statement-based questions, Conceptual understanding
-
Prelims 2021
Statement-based questions, Conceptual understanding
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Prelims 2023
Statement-based questions, Conceptual understanding
-
Prelims 2024
Factual recall, Conceptual understanding
-
Prelims 2025
Multi-statement analysis, Conceptual understanding
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Prelims 2026
Multi-statement analysis, Factual recall
-
Beyond high temperatures: understanding heat stress in Tamil Nadu
UHI effect causes urban areas to be hotter than rural surroundings due to built environments and human activities. It exacerbates heat stress, particularly at night, and necessitates urban greening and sustainable construction for mitigation.
See also
Past papers
2013–2026 · 7 questions
In the news
Beyond high temperatures: understanding heat stress in Tamil Nadu
UHI effect causes urban areas to be hotter than rural surroundings due to built environments and human activities. It exacerbates heat stress, particularly at night, and necessitates urban greening and sustainable construction for mitigation.
Try these PYQs
Consider the following statements :
Statement-I: The temperature contrast between continents and oceans is greater during summer than in winter.
Statement-II: The specific heat of water is more than that of land surface.
Which one of the following is correct in respect of the above statements?
Statement-I is incorrect: The temperature contrast between land and ocean is actually greater in winter, not in summer. In winter, land loses heat quickly and becomes much colder, while the ocean retains heat and stays relatively warm → large contrast.
In summer, both land and ocean warm up, but the difference is less pronounced compared to winter → smaller contrast. Statement-II is correct: Water has a higher specific heat capacity than land. It heats up and cools down more slowly, which explains why oceans have a moderating influence on temperature.
The annual range of temperature in the interior of the continents is high as compared to coastal areas. What is/are the reason/reasons?
1. Thermal difference between land and water
2. Variation in altitude between continents and oceans
3. Presence of strong winds in the interior
4. Heavy rains in the interior as compared to coasts
Select the correct answer using the codes given below.
The correct answer is 1 only (Thermal difference between land and water). Statement 1 is correct: Land heats up and cools down much faster than water. This is because water has a higher specific heat capacity, meaning it takes more energy to heat it up and more energy to cool it down. Coastal areas, being influenced by large water bodies, experience a moderating effect on temperature fluctuations. The temperature changes are more gradual throughout the year. Statement 2 is incorrect: While altitude can affect temperature (higher altitude generally means cooler temperatures), this is not the primary reason for the difference between continental interiors and coasts. Both continents and oceans have variations in altitude. Statement 3 is incorrect: Winds can play a role in influencing local temperatures, but their presence wouldn't explain the consistent pattern of higher annual ranges seen in continental interiors. Statement 4 is incorrect: Rainfall patterns can affect temperature to some extent, but coastal areas often receive more rainfall compared to continental interiors. This wouldn't explain the higher annual range observed inland.
Consider the following statements:
Statement I:
In January, in the Northern Hemisphere, the isotherms bend equatorward while crossing the landmasses, and poleward while crossing the oceans.
Statement II:
In January, the air over the oceans is warmer than that over the landmasses in the Northern Hemisphere.
Which one of the following is correct in respect of the above statements?
✅ Statement I: Correct
In January, isotherms bend equatorward over land (which cools faster) and poleward over oceans (which retain heat). ✅ Statement II: Correct
Oceans stay warmer than land in January because water has a higher specific heat. ✅ Relationship:
Statement II explains why the isotherms behave as described in Statement I. Correct Answer: Both statements are correct, and Statement II explains Statement I.
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
1. OMT is measured up to a depth of 26°C isotherm which is 129 meters in the south-western Indian Ocean during January-March.
2. OMT collected during January-March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
Select the correct answer using the code given below:
Statement 1 is incorrect. OMT is measured up to the depth of the 26°C isotherm, but the 129-meter depth mentioned in the southwestern Indian Ocean during January-March is incorrect. The depth of the 26°C isotherm can vary depending on the region and season. Statement 2 is correct. OMT collected during January-March helps in predicting the amount of rainfall during the monsoon. It is used to assess whether rainfall will be more or less than the long-term average, as variations in OMT influence monsoon behaviour. Hence, option B is the correct answer.
Consider the following statements:
1. In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
2. In the temperate zone, westerlies make the eastern sections of oceans warmer than the western sections.
Which of the statements given above is/are correct?
Statement 1 is correct. The trade winds in the tropical zone blow from east to west, causing the western sections of the oceans to be warmer than the eastern sections. This is because these winds push the warm surface waters towards the west. Statement 2 is correct. On the other hand, in the temperate zone, the westerlies blow from west to east. These winds push the warm waters towards the eastern sections of the oceans, making them warmer than the western sections. Therefore, both statements are correct.
Show 2 more PYQs
With reference to the climate of Andaman and Nicobar Islands, which of the following statements is/are correct ?
1. The climate can be defined as a humid, tropical coastal climate.
2. It receives rainfall from both South-west monsoon and North-east monsoon.
3. Maximum precipitation is between December and May.
Select the answer using the code given below :
Statement 1 is Correct: The Andaman and Nicobar Islands feature a humid, tropical coastal climate. Due to their equatorial proximity and oceanic surroundings, they experience uniform warm temperatures (averaging 23°C to 31°C) and high relative humidity (approximately 80%) year-round. Statement 2 is Correct: The archipelago is unique in its rainfall pattern, as it receives substantial precipitation from both the South-West Monsoon and the North-East Monsoon. Statement 3 is Incorrect: The maximum precipitation occurs during the South-West monsoon season, specifically between May and September (peaking heavily in July and August). The period between December and May is actually the driest part of the year, making it the peak tourist season. It does not receive the maximum precipitation during this time. Therefore, the correct option is B.
One of the following regions has the world's largest tropical peatland, which holds about three years worth of global carbon emissions from fossil fuels; and the possible destruction of which can exert detrimental effect on the global climate. Which one of the following denotes that region?
Congo Basin Peatlands: The Congo Basin in Central Africa is home to the world's largest tropical peatland complex. This vast peatland stores an immense amount of carbon, estimated to be equivalent to about three years of global fossil fuel emissions. Importance of Peatlands: Peatlands are a critical carbon sink. They store more carbon than all the world's forests combined. When peatlands are drained or degraded, this stored carbon is released into the atmosphere, contributing to climate change. The Republic of Congo, the Democratic Republic of Cong and Indonesia are parties to the Brazzaville Declaration, aimed at protecting the Cuvette Centrale region in the Congo Basin, the world’s largest tropical peatlands, from unregulated land use and preventing its drainage and degradation. _Other Options:_ * Amazon Basin: While the Amazon is known for its vast rainforests, it is not the primary location of the world's largest tropical peatland. * Kikori Basin: The Kikori Basin is located in Papua New Guinea and contains significant peatlands, but not the largest tropical peatland complex. * Rio de la Plata Basin: This basin in South America is primarily known for its grasslands and is not associated with major peatland areas.