How Do Urban Areas Modify Their Climates

406 Words2 Pages
To what extent do urban areas modify their climate? Urban areas continually try and modify their climate in a number of ways, although it can sometimes been seen as difficult and ineffective. Firstly urban heat islands can be seen to increase climates therefore urban areas are repeatedly trying to reduce the effects of them. Urban Heat Island refers to the tendency for a city or town to remain warmer than its surroundings, by as much as 10 degrees or more. This effect is caused mostly by the lack of vegetation and soil moisture in urban areas, which would normally use the absorbed sunlight to evaporate water as part of photosynthesis, which is known as a process is called evaportranspiration. Because urbanized land areas cover only a very small fraction of the Earth, the effect of the urban heat island on global average temperatures is very small. Most thermometers are located in urbanized areas; those areas tend to become more urbanized over time. Many buildings found in urban areas have dark surfaces. Dark surfaces absorb more light energy, and heat, making the entire building warmer. Buildings with brick walls or roofs, if coated with dark coatings, also get heated up very quickly. In both cases, this heat is transferred both inside the structure and radiated into the surrounding air. Buildings with dark surfaces heat up more rapidly and require more cooling from air conditioning, which requires more energy from things such as power plants, resulting in more pollution. Also air conditioners exchange heat with atmospheric air, causing further local heating. Additionally, concrete, needed for the expansion of cities, absorb huge amounts of heat, increasing the mean surface temperatures of urban areas. Tall buildings, and often, accompanying narrow streets, hinder the circulation of air, reduce the wind speed, and thus reduce any natural cooling effects.
Open Document