What are the causes of Urban Heat Island ?

Urban Heat Islands are densely populated urban or metropolitan areas having higher temperatures compared to their surrounding areas.Several factors that contribute towards the formations of Urban Heat Islands can be listed as follows:

• Increased Air Pollution – Air pollutants like CO₂ are known to store heat resulting in the rise of atmospheric temperature.
• High Absorption of Solar Radiation – Use of low albedo materials (materials that have high absorptive rates for solar energy, mainly heat) in construction of roads, pavements, roof tops results to increase in local temperatures.
• Highly Restricted Air Flow – Densely structured urban areas pose as obstacles for Wind reducing its speed. This in turn reduces the cooling effect by convection.
• Low cooling efficiency due to less Vegetation – Different types of vegetation absorbs CO₂ from the surroundings for photosynthesis along with the solar heat increasing the cooling efficiency in the urban areas.
• Increased consumption of fuel to counter rise in temperatures – Consuming additional fuel releases more pollutants into the atmosphere.