GREENHOUSE EFFECT

1. GREENHOUSE EFFECT Eylül Baylaz 12-C 31265

2. TheGreenhouseEffect is basically, thetrapping of heat in theatmosphere. • It was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896. • In the absence of the greenhouse effect the Earth's average surface temperature would be about -19 °C, but now it is about 16 °C, which is the optimum temperaturefororganismstolive. Greenhouse Effect

3. The electromagnetic radiation from the Sun, is reflected as infrared radiation from the Earth’s surface. • Some of this infrared radiation is absorbed by the greenhouse gases in the atmosphere. • The absorbed energy in the atmosphere reradiates and warms up the surface of Earth. Greenhouse Effect Process

7. In other words, the greenhouse effect allows visible and UV light of short wavelength to pass through the atmosphere, to heat the air and the Earth, but it traps the longer wavelength infrared heat rays, emitted from the warm soil and air, therefore raising the temperature of the atmosphere. • The rate of this process is increasing as more than neccessary greenhouse gases are being produced. Greenhouse Effect Process

8. Thereasonwhythe rate of greenhouseeffectprocessincreases, is thatthegasesthatabsorbstheradiatedenergyfromtheEarth’ssurfaceincreases. • Themajorgreenhousegasesare: • Methane CH4 • WaterVapour H2O • Carbondioxide CO2 • DinitrogenMonoxide N2O • Ozone O3 • ChlorflourocarbonsCFCs Greenhouese Gases

9. Atmosphericconcentrations of thegreenhousegaseshaveincreasedsignificantly since theindustrialrevolution: CO2increased 25%, CH4increasedover 145% and N2O around 15%. • Theusage of CFCsare in decline as theusage is beingcontrolledbylegislation. • However not allthegaseshavethesameabilityto trap infraredradiation. Theiratmosphericconcentrationsandatmosphericlifetimesdifferfromoneanother. GreenhouseGases

10. Greenhouse Gases,Sources and Effectiveness

12. Global Warming • Global warming is the increase in the average temperature of the Earth's near-surface air and oceans. It is causedbytheincrease in thegreenhouseeffect. Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980 Global mean surface temperature anomaly relative to 1961–1990

13. Global Warming • The rate of change in the temperature is increasing significantly nowadays than any other changes observed in the last 10,000 years. • Ice cores provide evidence to theincrease the in theconcentration of greenhouse gases over the past 800,000 years. Both CO2 and CH4 vary between glacial and interglacial phases, and concentrations of these gases correlate strongly with temperature, i.e. Directly proportional.

14. Effects of Global Warming • Theeffects of Global Warmingoverthelastcenturyhaveresulted in: • An increase in temperaturebyabouthalf a degreecentigrade, • About 15-20 cm worldwiderise in sealevelsresultingfromthepartialmelting of glaciersand polar ice-capsandthephysicalexpansion of oceanwatercausedbywarmertemperatures.

15. What Can Be Done ToPrevent Global WarmingFromProgressing? • We should avoid the excess usage of air conditioners, deodorants, etc. • We should lead people to use public transport. • We should limit the usage of fossil fuels. • We should prevent forest fires. • We should increase afforestation.

16. QuestionsAppeared in the IB Exams • The natural greenhouse effect can be summarised in these steps. • I. About half of the radiation entering the Earth’s atmosphere is absorbed by the Earth’s surface. • II. This absorbed radiation is re-radiated from the Earth’s surface. • III. Greenhouse gases in the atmosphere absorb the radiation from the Earth’s surface and re-radiate it back to the Earth’s surface. • One predicted consequence of the enhanced greenhouse effect is rising sea levels. Outline two different ways in which this could happen. • .............................................................................................................................................. • .............................................................................................................................................. • (Total 2 marks) • Global warming is thought to be partly caused by the increasing concentration of carbon dioxide in the atmosphere. Discuss the effects of global warming. • .............................................................................................................................................. • (Total 3 marks) • Large-scale combustion of fossil fuels has been a major source of increased levels of CO2 in the atmosphere. • (a) Describe a possible effect of higher levels of CO2 in the atmosphere. • .................................................................................................................................... • .................................................................................................................................... • (1) • (b) Explain how the effect in (a) is caused by the interaction between CO2 and different types of radiation in the atmosphere. • .................................................................................................................................... • .................................................................................................................................... • (2) • (Total 3 marks)

17. (a) List two gases which contribute to the greenhouse effect. • ..................................................................................................................................... • (1) • (b) Explain how greenhouse gases cause global warming. • ..................................................................................................................................... • (c) State one man-made source of particulates and outline the effect of particulates on the Earth’s surface temperature. • ..................................................................................................................................... • (2) • (Total 6 marks)

18. The natural greenhouse effect can be summarised in these steps. • I. About half of the radiation entering the Earth’s atmosphere is absorbed by the Earth’s surface. • II. This absorbed radiation is re-radiated from the Earth’s surface. • III. Greenhouse gases in the atmosphere absorb the radiation from the Earth’s surface and re-radiate it back to the Earth’s surface. • (a) (i) Identify the part of the spectrum from which most of the absorbed radiation in step I comes. • ......................................................................................................................... • (1) • (ii) Identify the part of the spectrum from which most of the radiation in step II comes. • ......................................................................................................................... • (1) • (iii) Explain on a molecular level, how greenhouse gases absorb the radiation in step III. • ......................................................................................................................... • (1) • (iv) The term enhanced greenhouse effect is sometimes used to describe the increasing effect of human activity on the natural effect. • Explain why, with reference to one of the steps above, the greenhouse effect may be increasing. • ......................................................................................................................... • (2) • (b) “Carbon dioxide is the most significant greenhouse gas.” • “Methane is a more important greenhouse gas than carbon dioxide.” • Explain how both these statements can be considered correct. • .................................................................................................................................... • (2) • (Total 7 marks)

19. Thetermgreenhouseeffectis usedtodescribe a naturalprocessforkeepingtheaveragetemperature of theEarth’ssurfacenearlyconstant. • (a) Describethegreenhouseeffect in terms of radiations of differentwavelengths. • ..................................................................................................................................... • (4) • (b) Watervapouracts as a greenhousegas. Statethemainnaturalandman-madesources of watervapour in theatmosphere. • (2) • Naturalsource ............................................................. • Man-madesource .......................................................... • (c) Twostudentsdisagreedaboutwhethercarbondioxideormethanewasmoreimportant as a greenhousegas. • (i) Stateonereasonwhycarbondioxidecould be consideredmoreimportantthanmethane as a greenhousegas. • ........................................................................................................................... • ........................................................................................................................... • (1) • (ii) Stateonereasonwhymethanecould be consideredmoreimportantthancarbondioxide as a greenhousegas. • ........................................................................................................................... • ........................................................................................................................... • (1) • (d) Discusstheeffects of global warming on theEarth. • ..................................................................................................................................... • (4) • (Total 12 marks)