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E2 Infrared (IR) Spectroscopy

E2 Infrared (IR) Spectroscopy. Vivien Tsang and Melody Mak. What is the Greenhouse effect?. The greenhouse effect is a natural process The atmosphere traps some of the energy that comes from the sun This energy provides warmth to support life on Earth However

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E2 Infrared (IR) Spectroscopy

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  1. E2 Infrared (IR) Spectroscopy Vivien Tsang and Melody Mak

  2. What is the Greenhouse effect? • The greenhouse effect is anatural process • The atmosphere traps some of the energy that comes from the sun • This energy provides warmth to support life on Earth However • Due to an increase in human activity, there has been a significant rise in the concentration of greenhouse gases • This leads to global warming

  3. The Greenhouse effect & Radiation • Radiation from the sun reaches the Earth through short wavelength ultraviolet radiationand visible radiation • These are either: 1) Reflected back into space 2) Absorbed by the atmosphere before reaching Earth’s surface • Energy radiated from the Earth’s surface are longer wavelength infrared radiation but not all of it escapes back into space

  4. So how is the greenhouse effect caused? Greenhouse gases: • allow the passage of incoming short wavelength radiation (UV and visible radiation) • Absorb some of the reflected longer wavelength radiation, so that these are radiated back to Earth’s surface Therefore greenhouse gases cause heat to be trapped as some radiation cannot escape

  5. The Greenhouse effect • The relative effect of greenhouse gases on global warming depend on: - its concentration/abundance in the atmosphere - its ability to absorb infrared heat • Wateris the main greenhouse gas because it is the most abundant • CO2contributes about 50% to global warming • Bonds in CO2 absorb a different wavelength of radiation. Even though it only constitutes 0.03% of the atmosphere, it has a significant role in maintaining the average global temperature (around 15˚C)

  6. The Greenhouse gases: Sources

  7. Influence on global warming Consequences: • Changes in agriculture and biodistribution • Rising sea levelsdue to thermal expansion and melting of the polar ice caps. This leads to: => increased flooding => oceans absorbing more heat => more hurricanes and typhoons • Significant changes in world weather patterns • Increased risk of diseasese.g. Malaria – mosquitoes spread to areas of warmer climate • Economic problems as tourism pattern changes • Problems of maintaining a sufficient supply of fresh drinking water

  8. Influence of particulates • Particulates have the opposite effect to greenhouse gases • They are able to lower the temperature by scattering short wavelength radiation so that it is reflected back into space • Examples of particulates: soot, ash, volcanic dust

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