Essay On Urban Heat Island

Temperatures are increasing in cities than that in surrounding rural areas. This kind of phenomenon is called Urban Heat Island and in this report, it will refers to UHI. The temperature difference is usually larger at night than during the day, and is most apparent when winds are weak. The main cause of the UHI is from the modification of land surfaces, which use materials that effectively store heat. As a population center grows, it tends to expand its area and increase its average temperature (Mary, 2005). In this paper, I will talk about the causations, diurnal behaviors, health effects and how to mitigate this problem.

There are several causations for UHIs: throughout the daytime, urban surfaces are warmed by the absorption of solar radiation. Surfaces in the urban areas tend to warm faster than those of the surrounding rural areas. Materials commonly used in urban areas for pavement and roofs, such as concrete and asphalt, have significantly different thermal bulk properties and surface radiative properties from the rural areas (Oke, 1982). Another

Firstly, painting rooftops white has become a common strategy to reduce the heat island effect. In cities, there are many dark colored surfaces that absorb the heat of the sun in turn lowering the albedo of the city. White rooftops allow high solar reflectance and high solar emittance, increasing the albedo of the city or area the effect is occurring. Green roofs are another ways to mitigate the problem. It is the practice of having vegetation on a roof, such as having trees or a garden. Last but not least, planting trees around the city can increase albedo and decreasing the UHI effect. Trees could increase the absorption of carbon dioxide and provide shade. It is recommended to plant deciduous trees because they can provide many benefits such as more shade in the summer and not blocking warmth of