“Urban Areas Have a Significant Impact on Climatic Characteristics.” Discuss This Statement

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“Urban areas have a significant impact on climatic characteristics.” discuss this statement (40 marks) The weather is often very different in urban areas than the surrounding rural areas, variations can occur in temperature, humidity, precipitation, visibility and air quality. The urban canopy layer is the areas just below roof level where processes take place between buildings and the urban boundary layer is the dome over an urban area which extends downwind. Temperature is one characteristic which is clearly affected by an urban area, the edge of the boundary layer is often well defined by a steep temperature increase which then increases more gradually towards the CBD (central business district) where is plateaus. Many factors contribute to this urban heating effect such as heat being generated from industries, buildings and vehicles which all burn fuel but people themselves often produce heat so cities with a high population density will experience a greater urban heat island effect. The difference between urban and rural areas is more visible at night as materials in a city centre (e.g concrete) absorb the heat energy from the sun during the day and the release the energy at night, many buildings in a CBD reflect sunlight downwards amplifying the heating effect. Another contributor is the lack of surface water, in a city centre water is rapidly disposed of which means energy is not used for evapotranspiration and more is used to heat the atmosphere. Urban areas can also effect the precipitation, many urban areas experience heavier and more frequent rainfall, a greater amount of thunderstorms but reduced snowfall due to higher temperatures. Due to the effect of temperature the urban heat island effect generates convection, higher temperatures also cause lower pressures to develop. The pollutants in an urban area act as hydroscopic nuclei for water vapour which causes raindrops to form, all of these factors are associated with higher rainfall over an urban...
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