Downloaded 34 times
More Related Content
![Global Warming P P T [97 03]](https://cdn.slidesharecdn.com/ss_thumbnails/globalwarmingppt97-03-090408023255-phpapp02-thumbnail.jpg?width=640&height=640&fit=bounds)
Global issues
- 1. Global Issues Presentation by: Harmandeep,Thang, Safir
- 2. 9.1 Global 4000 Warming The Fact: islandsin Indonesia will drown in the upcoming years due to rising sea levels caused by Global Warming.
- 3. What is GlobalWarming? Global Warming refers to the increasing temperature of earth's surface due to the excess heat trapped into our atmosphere. This takes place due to enhanced green house effect.
- 4. What is Greenhouseeffect? The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's surface. This keeps the Earth warm and a nice place to live in, keeping us all happy.
- 5. “Enhanced” greenhouse effect Thesedays, human activities produce too much greenhouse gases that makes the earth’s atmosphere thicker, making it impossible for the Sun rays to reflect back into the atmosphere. Hence, the Sun rays get stuck into the earth's atmosphere, making it too hot to live in. This is called Enhanced Greenhouse Effect and is what's causing Global Warming.
- 6.
- 7. Carbon Dioxide - Producedby burning fossil fuels such as gas, petrol, aviation petrol, diesel and oil
- 8. Methane - Produced when youburp or fart. Twenty –one times more effective than carbon dioxide in blocking the escape of radiant heat.
- 9. Nitrous Oxide - Producedfrom burning forests, car exhaust, jet fuel and artificial fertilizers.
- 10. Chlorofluorocarbons (CFCs) - Invented in1920s. Were found in aerosol spray cans and as coolant gases on refrigerators. Non-poisonous. Odourless. Were once called ‘wonder chemicals’. Stable and cheap to produce.
- 11. Surface Ozone - Generated asa part of photochemical smog. Produced by the action of sunlight on motor vehicle and industrial pollution.
- 12. Australian greenhouse gas production Carbondioxide Methane Nitrous Oxide Other
- 13. Evidence of globalwarming #1- Glaciers have been melting.
- 14. Evidence of globalwarming #2- Icebergs are breaking off.
- 15. Evidence of globalwarming #3- Ice sheet in Greenland is getting thinner.
- 16. Evidence of globalwarming #4- Coral reefs in the Caribbean are now permanently bleached.
- 17. Evidence of globalwarming #5- Alpine plant species has fallen.
- 18. Evidence of globalwarming #6- Snowgums in Australia have shifted 40 meters up the mountain.
- 19. El Niño effect ElNiño effect occurs in which trade winds weaken or reverse, allowing warmer water to move towards the west coast of South America around Christmas time. The result is that Australia experiences drought, and South America experiences increased rainfall.
- 20.
- 21. What is Ozone? Ozoneis naturally occurring form of oxygen, each molecule comprising three atoms.
- 22. Ozone Layer Ozone iscreated when UV light splits oxygen molecules into single atoms. These single oxygen atoms then join other oxygen molecules to form triplets of oxygen atoms, or ozone molecules. UV light also splits ozone molecules, so ozone is continually being created and destroyed, with UV light being absorbed in the process . The region, in which ozone is thinly distributed is referred to as the ozone layer.
- 23. Dobson Unit - - Measuresthe thickness of the ozone layer. A value of less than 220 DU is considered to be an ozone hole. If all the ozone molecules in the ozone layer were brought to ground level, it would form a sheet averaging only 500 DU(5mm) thick.
- 24. The future: Kyoto Protocol - Formedin 1987 to stop manufacturing of CFCs. One hundred nations signed up. The agreement is expected to bring the ozone levels back to normal by 2045.
- 25.
- 26. Radiation and Radioactivity - An elementwhose atoms emit nuclear radiation is said to be radioactive. - Example: Uranium.
- 27. Atoms and Isotopes - Isotopesare atoms of the same element that have different numbers of neutrons in their nuclei. A radioactive isotope is called a radioisotope. When referring to a radioisotope, often just its mass number is given. Example: Lithium.
- 28. Types of NuclearRadiation - Alpha radiation Beta radiation Gamma radiation
- 29. Alpha Radiation - Thethrown out cluster from radioactive nuclei is known as alpha particle. - Its done so to make the nuclei smaller and more stable. - Alpha particles move at speeds of up to one-tenth of the speed of light. - Alpha particles are stopped by a thick sheet of paper or human skin.
- 30. Beta Radiation - Whenthere is an imbalance of neutrons and protons in a nucleus, a neutron may change into a proton and an electron. The newly created electron is called a beta particle. - Beta radiation can be blocked using aluminum sheet of 1mm.
- 31. Gamma Radiation - Sometimeswhen an alpha particle or beta particle is emitted from nucleus, the new nucleus is still unstable and emits extra energy in the form of gamma ray to become even more stable. - Gamma rays can only be blocked by a thick piece of lead or concrete.
- 32. Half-Life - Half-life isthe time taken for half the atoms in a sample to decay. - Example: quantity of radon-222 halves every four days.
- 33. Carbon Dating - Used todate back dead organisms. - It is done by comparing the amounts of carbon-14 and carbon-12 in the organism.
- 34. Uses of NuclearRadiation #1- Used in radiotherapy to treat cancer.
- 35. Uses of NuclearRadiation #2- Used to detect thickness of paper.
- 36. Uses of NuclearRadiation #3- Used in hospitals to sterilize medical equipment.
- 37.
- 38. Nuclear Fission - Itswhen uranium hits the neutron and as a result the neutron becomes very unstable and that produces heat and energy.
- 39. Nuclear Fusion - Itswhen tritium and deuterium combine together releasing neutron. It produces energy and heat.
- 40. Other Alternatives #1- SolarEnergy.
- 41. Other Alternatives #2- WindEnergy.
- 42.
- 43. #1- Think Green #2- DoGreen #3- Share Green Save The Earth