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Meteorology: General Circulation

Air pollution is directly affected by various aspects of meteorology, such as winds, which transport pollutants (in some cases over long distances); turbulence, which disperses air pollutants; solar radiation, which initiates photochemical reactions leading to the formation of ozone, fine particles, and acid rain; high pressure systems, which are conducive to air pollution episodes because of their calm and sunny conditions; and precipitations, which scavenge air pollutants and transfer them to other media (e.g., acid rain). Therefore, it is essential to understand general meteorological features before addressing in detail the processes that are specific to air pollution. This chapter presents first some general considerations on the atmosphere (chemical composition, pressure, and temperature). Next, the main aspects of the general atmospheric circulation are described.