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The Greenhouse Effect. The Greenhouse Effect. Earth will always reach a balance of energy. Amount of energy absorbed is equal to amount of energy emitted . The Role of the Climate System. Without Earth’s climate system, the planet would be much colder than it is now.
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The Greenhouse Effect • Earth will always reach a balance of energy. • Amount of energy absorbed is equal to amount of energy emitted.
The Role of the Climate System • Without Earth’s climate system, the planet would be much colder than it is now. • The climate system helps to maintain Earth’s temperature by trapping and storing energy from Sun and spreading it around the world. • Greenhouse Effect: a natural process where gases and clouds absorb infrared radiation emitted from the Earth’s surface and radiate it, heating the atmosphere and Earth’s surface.
What is the Greenhouse Effect? • The atmosphere allows radiation (higher-energy) from the Sun to pass through • Radiation is absorbed by the Earth’s surface • This energy becomes thermal energy and warms the surface • The surface emits infrared radiation • Gases in the atmosphere trap much of the IR radiation, radiating the energy in all directions, sending some back to the surface • This warms the surface even more
Greenhouse Gases • Most of the air is made up of nitrogen and oxygen gases • These gases do not absorb radiation from the Earth’s surface
Greenhouse Gases • The greenhouse effect is caused by gases in very low concentrations, known as the greenhouse gases • Water vapour (H2O) – most important • Carbon dioxide (CO2) • Methane (CH4) • Ozone (O3) • Nitrous oxide (N2O) • Their contribution to the greenhouse effect is determined by their concentration and by how much thermal energy each molecule can absorb
Carbon Dioxide • Concentration in atmosphere: 0.0385% or 385 parts per million • Estimated to cause up to a quarter of the natural greenhouse effect • Concentration before the Industrial Revolution: 280 parts per million • Natural sources of CO2 include: volcanic eruptions, burning of organic matter and cellular respiration
The Carbon Cycle • Movement of carbon through the components of the climate system • Living things and the Oceans are important Carbon sinks, meaning they remove carbon dioxide from the atmosphere and store the carbon in a different form • Trees and plants capture CO2 to make food through photosynthesis • When trees and plants decompose or burn, the carbon is released back into the atmosphere as CO2. • Carbon dioxide dissolves in the oceans and some form calcium carbonate, which sinks to the bottom
http://www.sciencelearn.org.nz/Contexts/The-Ocean-in-Action/Sci-Media/Animations-and-Interactives/Carbon-cyclehttp://www.sciencelearn.org.nz/Contexts/The-Ocean-in-Action/Sci-Media/Animations-and-Interactives/Carbon-cycle
Water Vapour • About two-thirdsof the greenhouse effect is caused by water vapour • Quantity of water vapour in the atmosphere depends on the temperature of the atmosphere • Feedback Look • A process in which the result acts to influence the original process • Water evaporates more when it is heated. Warm air also can hold more water vapour. Because water vapour traps energy, the temperature continues to rise, causing more evaporation • Positive Feedback: effect increases the original cause • Negative Feedback: effect decreases the original cause
Methane • Much less methane than carbon dioxide in the atmosphere • Methane can hold much more thermal energy than carbon dioxide • 23 times more powerful of a greenhouse gas than CO2 • Produced naturally from plant decomposition in swamps and animal digestion, but also human sources • Concentration before the Industrial Revolution: 0.700 parts per million • It is now 1.785 ppm
Ozone • Ozone gas forms a protective layer in the Stratosphere, protecting the surface from UV-radiation • In the troposphere, its acts as a greenhouse gas
Nitrous Oxide • Molecule of N2O is almost 300 times more effective than a molecule of CO2 • Less available than CO2 • Concentration before the Industrial Revolution: 0.270 parts per million • Risen to 0.321 ppm • Produced both naturally and by human sources • Naturally through reactions of bacteria in soil and water
How do Greenhouse Gases Trap Infrared Radiation? • Greenhouse gases make up so little of our atmosphere, yet play an essential role in keeping our planet habitable. How? • Nitrogen (N2) and Oxygen (O2) gas consist of identical atoms – they can only vibrate one way: back and forth, limiting the type of energy the molecules can absorb • When infrared radiation hit these molecules, they cannot absorb it • Greenhouse gases have different types of atoms and can vibrate in different directions • They can absorb different types of energy, including infrared radiation, which it can re-emit in every direction
Please Complete • P342 #1-7