The heat island effect, specifically known as the urban heat island (UHI) effect, occurs when urban or developed areas experience significantly higher temperatures than their surrounding rural areas. This temperature difference arises because urban surfaces like buildings, roads, and pavements absorb and retain more heat from the sun compared to natural landscapes such as forests, grasslands, or water bodies
. Key aspects of the heat island effect include:
- Causes :
- Urban materials such as concrete and asphalt have high heat capacities and absorb more solar radiation, heating up faster and retaining heat longer.
- The geometry of cities-with tall buildings and narrow streets-traps heat and reduces airflow, a phenomenon called the "urban canyon effect."
- Reduced vegetation and green spaces limit natural cooling through shade and evapotranspiration.
- Waste heat from human activities like vehicles, air conditioning, and industry also contributes to warming
- Characteristics :
- Urban areas can be 1–7°F (0.55–3.9°C) warmer than rural areas during the day and 2–5°F (1.1–2.8°C) warmer at night, with nighttime differences often more pronounced.
- Heat islands can vary within a city, with downtown and heavily built-up areas hotter than parks or vegetated neighborhoods.
- There are two types: surface heat islands (warmer surfaces) and atmospheric heat islands (warmer air)
- Impacts :
- Increased energy consumption due to higher demand for air conditioning.
- Decreased air quality from enhanced pollutant formation.
- Altered local weather patterns, such as increased rainfall downwind of cities.
- Stress on ecosystems from warmer water runoff and longer growing seasons
In summary, the heat island effect is the phenomenon where urban areas become warmer than their rural surroundings due to human-made surfaces and activities that absorb and retain heat more effectively than natural environments
