Definitions

Heat Island describs built up areas that are hotter than nearby rural area. The annual mean air temperature of a city with 1 million people or more can be (1-3°C) wamer than ist surroundings. In the evening, the difference can be as high 12°C. it is appreciated by temperature difference at night and during the day, and the weakness of the winds. Urban Heat Island (UHI) is very noticeable during summer and winter.

Causes

Generally, the UHIs are caused by human activities, are from the modification of land surfaces.

The overpopulation can create also a UHI, because a small place with more people involves the construction of building so closely.

Effects

The UHIs affect the climate and the environment. So, they make environment suffers. The UHIs effects are :

• Increased energy consumption : it is marked by the increasing of energy demand for air conditioning durung summer with increased temperature.
• Elevated greenhouse gas emission and air pollution by using fossil fuel for energy production. It will cause global warming and climate change with air pollution.
• Poses danger to aquatic systems : the high temperatures in urban areas can heat stormwater runoff. It will flows into storm drainage systems and raises water temperatures, the the aquatic systems will be disturbed.The UHI provokes the thermal pollution. Then, the water quality also suffers.
• Discomfort and danger to human health : Because higher air pollution increased the diseases like headhaches, heat stroke and heat cramps.
• Secondary impacts on weatger and climate : the UHIs may have impacts on the local weathear and climate. It leads the changes of local wind to thunderstorm, the formation of fog, clouds, precipitation rates and humidity.
• Impacts on animals : the UHI perturb the ecosystem with the high temperature. Because it limits the essentail activities of the organims such as metabolism, breading and reproduction.

Solutions

To reduce the UHIs and to preserve our city, we should :

• Use light-colored concrete and white roofs which reflect up 50% more light and cut down the ambient temperature 
• Implant green roofs and vegetation cover which will be insulators during summer and will decrease the UHI efefct. Plants contribute to cool the surrounding environments 
• Plant trees in cities :trees will absorb the temperature and the carbon dioxide. Then, It will reduce the heat.
• Implement Green parking lots
• Implement and sensitize about heat reduction policies and rules

 So to preserve our cities, we should take action, should use to have eco-gesture and reduce our activities generating more waste energy.

 

https://www.nationalgeographic.org/encyclopedia/urban-heat-island/

http://www.conserve-energy-future.com/effects-solutions-urban-heat-island.php