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The General environmental problems of cities of the world.

The General environmental problems of cities of the world.

Environmental problems of cities, mainly largest of them, are connected to excessive concentration in rather small territories of the population, transport and the industrial enterprises, with formation of the anthropogenous landscapes very far from a condition of ecological equilibrium. Rates of growth of a world's population at 1.5-2.0 time are lower than growth of urban population to which today concerns 40 % of people of a planet. For the period 1939 - 1979 the population of large cities has grown in 4, on the average - in 3 and small - in 2 times.

Social and economic conditions has resulted in uncontrollability of process of a urbanization in many countries. The interest of urban population is equal the separate countries: Argentina - 83, Uruguay - 82, Australia - 75, USA - 80, Japan - 76, Germany - 90, Sweden - 83. Besides large cities - millionaires city agglomerations or the merged cities quickly grow. Are those Washington - in USA; cities of Ruhr in Germany; Moscow, Donbass and Kuzbass in the CIS.

Circulation of substance and energy in cities considerably surpasses those in a countryside. Average density of a natural stream of energy of the Earth - 180 Âò/m2, a share of anthropogenous energy in it - 0.1 Âò/m2. In cities she(it) grows till 30-40 and even up to 150 Âò/m2.

Above large cities the atmosphere contains in 10 times more aerosols and in 25 times more gases. Thus of 60-70 % of gas pollution are given with motor transport. More active condensation of a moisture results in increase of deposits at 5-10 %. Autopurification of an atmosphere is interfered by (reduction) on 10-20 % of solar radiation and to speed of a wind.

At small mobility of air thermal anomalies above city cover layers of an atmosphere in 250-400 m, and contrasts of temperature may reach 5-6 With. The temperature inversions resulting in raised pollution

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