Global Change.

Gabby Gabanic

Chapter 18-1

Power PlantsCoal-burning.Smoke released into the atmosphere through

smokestacks.Usually around 300 meters.Contains high concentrations of sulfur.Purpose: “To release sulfur-rich smoke high

into the atmosphere, where winds would disperse and dilute it.”

Power Plants (continued)Were first introduced in the mid- 1950s.Common in the United States and Europe.The sulfur released from the smokestacks can

combine with water vapor to produce sulfuric acid.

Snow/Rain bring the sulfuric acid back down to Earth.

Acid Rain“Acidified precipitation.”Northeastern United States and Southeastern

Canada is where it is most severe.They are areas that are “downwind from coal-

burning plants in the Midwest.”

Acid Rain Process

Impact of Acid RainForests in certain regions are being

damaged.Harming symbiotic fungi in tree roots.

The Ozone HoleScientists said “it was as if an ‘ozone eater’

were causing a mysterious zone of below-normal concentration.”

“Because the decrease in ozone allows more ultraviolet radiation to reach the Earth’s surface, scientists expect an increased incidence of diseases caused by exposure to ultraviolet radiation.”

Ex. Skin cancer, cataracts and cancer of the retina.

Ozone Hole

Destruction of the ozoneChlorofluorocarbons (CFC)- class of

chemicals.Considered extremely stable, harmless, and a

nearly ideal heat exchanger.Used as coolants.

Refrigerators and air conditioners. Aerosol propellants-spray cans. Foaming agents-production of plastic-foam cups and

containers.Primary cause of the ozone hole.

Destructions of ozone (cont.)“Ultraviolet radiation from the sun is able to

break the usually stable bonds in CFCs.”“The resulting free chlorine atoms then enter

into a series of reactions that destroy the ozone.”

Global TemperaturesTemperature of the Earth has been

increasing steadily since the 1950s.Global warming happens in periods.Sunspot cycles may contribute to this along

with human activity.

Greenhouse EffectGreenhouse effect- traps heat within the

atmosphere like the way a greenhouse traps in heat.

Greenhouse gases- insulating effects of certain gases.