Daily UPSC Mains Question - GS 1 - 15th November 2025
- TPP
- Nov 15
- 3 min read
Updated: Nov 16
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QUESTION
“Night-time minimum temperatures are more influenced by local conditions than large-scale geography.” Discuss the role of wind patterns, humidity, cloud cover, and land cover in influencing local climate, with an example.
Answer: Night-time minimum temperatures show high spatial variability even within the same climatic zone. While latitude, altitude and distance from the sea shape the broad climatic framework, localised factors such as wind regimes, humidity levels, cloud cover and land-surface characteristics play a decisive role in controlling radiative cooling at night.
Recent winter observations from Gujarat illustrate this micro-climatic influence—interior cities recorded lower minimum temperatures than Naliya in Kutch, a region generally known as one of the coldest in the state.
Role of Local Factors in Influencing Night-time Temperatures
1. Wind Patterns
Wind direction and speed directly control the movement of air masses and redistribution of heat.
Cold, dry continental winds enhance nocturnal cooling due to low moisture and high radiative loss.
Moist maritime winds from adjoining seas restrict cooling by increasing atmospheric stability and humidity.
Divergent wind patterns create micro-climatic pockets even within the same district.
Example from Gujarat:
Northeasterly/easterly winds over central and eastern Gujarat (e.g., Gandhinagar, Vadodara) transported cool, dry inland air, resulting in sharper night-time temperature drops.
Conversely, westerly/northwesterly winds over Kutch carried coastal moisture, moderating minimum temperatures in Naliya.
2. Humidity (Moisture Content in Air)
Humidity determines the air’s capacity to retain or lose heat through long-wave radiation.
Dry air cools rapidly due to higher radiative loss at night.
Moist air cools slowly, as water vapour—being a greenhouse gas—absorbs outgoing radiation.
Gujarat example:
Interior cities like Gandhinagar and Vadodara, with relatively dry post-rainy air, experienced quicker radiative cooling.
Coastal Kutch, influenced by sea-derived humidity, showed slower night-time heat loss, keeping minimum temperatures higher.
3. Cloud Cover
Clouds are one of the most significant regulators of minimum temperature.
Clear skies promote free radiative heat loss from the surface → lower minimum temperatures.
Cloudy nights act like an insulating blanket by reflecting long-wave radiation back to the surface → warmer minimum temperatures.
Field observation:
Weak western disturbances often bring cloudiness first to Kutch, reducing night-time cooling there.
Meanwhile, interior Gujarat remains clear and dry, resulting in colder nights.
4. Land Cover and Surface Characteristics
Land-surface properties directly affect heat absorption and nocturnal heat release.
Vegetated and moist surfaces (farmlands, parks, peri-urban zones) have higher evapotranspiration and lower heat absorption → cool rapidly at night.
Built-up, dry, rocky, or desert surfaces retain heat longer → slow night cooling.
Urban form (building density, impervious surfaces) shapes Urban Heat Island (UHI) effects.
Example:
Gandhinagar and Vadodara, with substantial green cover and open areas, cool faster.
Naliya, despite being in the arid zone, experienced slower cooling due to cloudiness and coastal moisture, overriding its desert heat-loss tendency.
Illustrative Example: Temperature Reversal in Gujarat (November 2024)
Gandhinagar recorded a minimum of 13.8°C, nearly 4°C below normal, while
Naliya, typically the coldest, remained around 14–15°C, warmer than interior regions.
This reversal occurred primarily due to:
Dry, cool easterly winds over central Gujarat
Moist westerly/northwesterly winds and some cloud cover over Kutch
Clear skies and greater green cover allowing enhanced radiative cooling in interior cities
This underlines that local atmospheric and surface conditions outweighed regional geographical expectations.
Night-time minimum temperatures are highly sensitive to micro-climatic conditions, especially wind flow, humidity distribution, cloudiness and land-surface features. The Gujarat episode demonstrates how interior urban centres with dry air and clear skies can become colder than traditionally colder coastal–desert locations. Understanding such fine-scale climatic behaviour is essential for accurate weather forecasting, urban planning and climate-responsive infrastructure design.
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