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Define Urban Heat Island and list out its causative factors and impacts. Suggest your solutions for evading urban heat islands.
Define Urban Heat Island and list out its causative factors and impacts. Suggest your solutions for evading urban heat islands.
Urban Heat Island:
- UHI is an urban area or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.
- The temperature difference usually is larger at night than during the day, and is most apparent when winds are weak.
Causative Factors:
- Excess heat arising from various sources like industries, home, agricultural burning in surrounding areas.
- Increased absorption of sunlight by the bricks and concrete materials of the city.
- The atmospheric pollution in the cities acts as a blanket in preventing outgoing radiation.
- Lack of vegetation in urban areas reduces the natural cooling effect.
- The tall buildings provides multiple surfaces for the reflection and absorption of sunlight, increasing the efficiency with which urban areas are heated (Urban Canyon Effect)
Impacts:
- Increased temperatures amplify energy demand for cooling systems contributing to higher electricity consumption.
- Increased energy demand results in huge emissions of greenhouse gases.
- Health is impacted due to general exhaustion, heat strokes, heat cramps, headaches and respiratory problems.
- It creates secondary impacts like changes in local wind patterns, precipitation rates and humidity, and formation of clouds and fog.
- It negatively impacts the fauna and flora present in urban areas.
Counter Measures:
- Using light coloured concrete, white roofs increase the albedo.
- Using green roofs (partially or complete vegetation over the roofs of buildings) results in insulation thereby reducing the air temperatures.
- Construction of resource-efficient and environmentally sustainable green buildings.
- Promoting urban forestry which results in a cooling effect.
- Promoting fuel efficiency to reduce greenhouse gas emissions.
Conclusion:
- Urban heat islands should be cooled off with immediate effect for ensuring a healthy as well as productive climate.
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