Urban Heat Islands For more than 100 years, it has been known that two adjacent cities are generally warmer than the surrounding areas. This region of city warmth, known as an urban heat island, can influence the concentration of air pollution. The urban heat island is formed when industrial and urban areas are developed and heat becomes more abundant. In rural areas, a large part of the incoming solar energy is used to evaporate water from vegetation and soil.
In cities, where less vegetation and exposed soil exists, the majority of the sun’s energy is absorbed by urban structures and asphalt. Hence, during warm daylight hours, less evaporative cooling in cities allows surface temperatures to rise higher than in rural areas. Additional city heat is given off by vehicles and factories, as well as by industrial and domestic heating and cooling units. At night, the solar energy, which is stored as vast quantities of heat in city buildings and roads, is released slowly into the city. The dissipation of heat energy is slowed and even stopped by the tall building walls that do not allow infrared radiation to escape as readily as do the relative level surfaces of the surrounding countryside.
The Essay on Violence enforcement of City Urban Management officers
City Urban Management Enforcement Bureau is a local government agency in mainland China that is in charge of maintaining the order of daily business activities of markets and streets in cities. This Bureau was established to deal with the increasing problems when China is in the process of rapid urbanization in these years. However, it’s notorious for abusing power and violent enforcement. ...
The slow release of heat tends to keep city temperatures higher than those of the unpaved faster cooling areas. On clear, still nights when the heat island is pronounced, a small thermal low-pressure area forms over the city. Sometimes a light breeze, called a country breeze which blows from the countryside into the city. If there are major industrial areas along the city’s outskirts, pollutants are carried into the heart of town, where they tend to concentrate. At night, the extra warmth of the city occasionally produces a shallow unstable layer near the surface. Pollutants emitted from low-level sources, such as home heating units, tend to concentrate in this shallow layer, often making the air unhealthy to breathe.
The constant outpouring of pollutants into the environment may actually influence the climate of a city. For an example, certain pollutants reflect solar energy, thereby reducing the sunlight that reaches the surface. Some particles serve as nuclei upon which water and ice form. Water vapor condenses onto these particles, forming haze that greatly reduces visibility. Moreover, the added nuclei increases the frequency of city fog. Pollutants from urban areas may even affect the weather downwind from them.
Just such a situation is described in a controversial study conducted at La Porte, Indiana, a city located about thirty miles downwind of the industries of south Chicago. Scientists suggested that La Porte had experienced a notable increase in annual precipitation since 1925. Because this rise closely followed the increase in steel production, it was proposed that the phenomenon was due to the additional emission of particles. As industrial output increases pollution particles increase available condensation nuclei, thus increasing rainfall. This process of increasingly wet climate is the result of industries to the west of La Porte. Bibliography:’ Disasters’, by Charles H.
V. Ebert ” Physical Geography Of The Global Environment’, by H. J. de B lij & Peter O.
Muller ” Essentials Of Meteorology’, by C. Donald Ahrens ” Compton’s Encyclopedia’, Prodigy On-line Edition.
The Essay on Urbanization: City and Urban Areas
The shift or movement to the city creates many opportunities for the people. It is very easy to find jobs in the city area and people can even operate as small businessmen. I would like to talk about my own city. Many multinational companies have been opening their offices in the city which has resulted in better job opportunities for all the people. People move to the urban areas in an effort to ...
