Urban Heat Island (UHI) refers to an area that is much warmer than the rural areas surrounding it. UHIs are created in areas that have lots of people and activity. The energy from from people, cars, buses etc create it.

 REASONS

• Building materials are good at insulating or holding in heat. Insulation around the closely constructed buildings makes the area warmer.
• Waste heat from people and their tools. Cars and factories, people whether jogging or driving or simply living their day to day lives, they are all burning off energy.
• Densely populated areas, resulting into densely constructed buildings. With no scope of exapansion, high rise buildings are constructed gives no space to insulated to go. It lingers in and between buildings.
• Buildings, sidewalks and parking areas built blocks the heat coming coming from ground from rising into the cold night sky. This results into high nighttime temperatures.

EFFECTS

• Worse air quality than the surrounding rural areas as more pollutants are pumped into the air. These pollutants are blocked from scattering and becoming less toxic by urban landscape.
• Water quality is also bad. When warm water ends up flowing into local streams, it stresses the native species that have adapted to life in a cooler aquatic environment.

When it’s really hot, many people run straight to the fan or air conditioning. This is especially true in urban areas that suffer from urban heat island effects. UHIs contribute to energy demands in the summer, straining energy resources. UHIs are often subject to “rolling blackouts,” or power outages. Utility companies start rolling blackouts when they do not have enough energy to meet their customers’ demands. The energy used in electric fans and air conditioning ends up contributing to an even hotter UHI.

Because of these negative effects, scientists say using green roofs (roofs of buildings covered in plants), helps cool things down. Plants absorb carbon dioxide, a leading pollutant. They also reduce the heat of the surrounding areas. Using lighter-colored materials on buildings helps, too. Light colors reflect more sunlight and trap less heat.