Identify the conditions which are favourable for the formation of urban heat islands:
(A) Clear sky (B) High albedo over urban areas (C) Low evapo-transpiration over urban areas (D) High wind speed
Choose the correct answer from the options given below:

Correct option is B

1. Clear Sky (A):
Favourable. Clear skies allow for maximum solar radiation to heat the urban surfaces during the day and limit heat loss at night, which intensifies the urban heat island effect.
2. High Albedo (B):
Not favourable. High albedo surfaces reflect more solar radiation, reducing heat absorption and mitigating the urban heat island effect.
3. Low Evapo-Transpiration (C):
Favourable. Urban areas with reduced vegetation have less evapo-transpiration, leading to less cooling from water evaporation and an increase in localized heating.
4. High Wind Speed (D):
Not favourable. High wind speeds disperse accumulated heat and reduce the temperature differences between urban and rural areas, thus lessening the urban heat island effect.
Hence, the conditions favourable for urban heat island formation are Clear Sky (A) and Low Evapo-Transpiration (C), making the correct answer (2).
Information Booster: 1. What is an Urban Heat Island (UHI)?
· It is the phenomenon where urban areas experience significantly higher temperatures than their surrounding rural areas due to human activities and modified land surfaces.
2. Key Contributing Factors:
· Low vegetation: Reduces natural cooling through evapo-transpiration.
· Impervious surfaces: Roads and buildings absorb and retain heat.
· Anthropogenic heat: Heat released from vehicles, industries, and air conditioning systems.
3. Impacts of Urban Heat Island:
· Increased energy consumption for cooling.
· Adverse health effects, especially heat-related illnesses.
· Reduced air quality due to the formation of ground-level ozone.
4. Mitigation Measures:
· Planting urban forests and green roofs.
· Using reflective building materials.
· Designing urban spaces for improved air circulation.
Additional Knowledge: · High Albedo (B):
· Albedo refers to the reflectivity of a surface. High albedo surfaces like white roofs reflect more sunlight, reducing urban heat accumulation.
· Clear Sky (A):
· Clear skies allow maximum solar radiation to heat urban surfaces and also limit radiative cooling at night.
· Low Evapo-Transpiration (C):
· Reduced vegetation in urban areas limits moisture release and cooling through evaporation, intensifying heat.
· High Wind Speed (D):
· Acts as a dispersing agent for heat, preventing the accumulation of warm air.