Environmental Problems, Their Causes, and Sustainability 1

Warmer airInversion layerIncreasing altitudeCool layerMountainMountainValleyDecreasing temperatureDescending warm air massInversion layerIncreasing altitudeSea breezeMountainrangeDecreasing temperatureFigure 20-7 Two sets of topography and weather conditions that lead to prolonged temperature inversions, inwhich a warm air layer sits atop a cooler air layer. Air pollutants can build to harmful levels during an inversion.Top, a temperature inversion can occur during cold, cloudy weather in a valley surrounded by mountains (top).Frequent and prolonged temperature inversions can also occur in an area with a sunny climate, light winds,mountains on three sides, and the ocean on the other. A layer of descending warm air from a high-pressuresystem prevents ocean-cooled air near the ground from ascending enough to disperse and dilute pollutants.Because of their topography, Los Angeles and Mexico City have frequent temperature inversions, many ofthem prolonged during the summer.son. It may even play a role in the intensity and frequencyof the El Niño–Southern Oscillation (ENSO)climate cycle (Figure 6-12, p. 108) and may thus affectNorth and South America and other parts of theworld (Figure 6-13, p. 109).The history of air pollution control in Europe andthe United States shows that atmospheric hazes can becleared up fairly quickly. This is done by setting standardsfor coal-burning industries and utilities, shiftingfrom coal to cleaner-burning natural gas in industriesand dwellings in urban areas, relying more on renewableenergy resources such as wind and hydropowerto produce electricity, and requiring catalytic converterson cars. China is beginning to do this and hopes torestore clear blue skies to Beijing by the 2008Olympics. India’s capital city of Delhi has also madeprogress in reducing air pollution under orders fromIndia’s Supreme Court.http://biology.brookscole.com/miller14443