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Unit 8 Acid rain, smog and global warming Unit 8 Acid rain, smog and global warming.

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Presentation on theme: "Unit 8 Acid rain, smog and global warming Unit 8 Acid rain, smog and global warming."— Presentation transcript:

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2 Unit 8 Acid rain, smog and global warming Unit 8 Acid rain, smog and global warming

3 Are there acids in the air? Acid rain is also called acid precipitation (snow, rain, fog, and dry particulate acidic depositions). Unit 8 Acid rain, smog and global warming Sulphur dioxide is emitted primarily from stationary sources such as power plants that burn fossil fuels. Sulphur dioxide H2OH2O Sulphuric acid Nitrogen oxides H2OH2O Nitric acid Nitrogen oxides are emitted from both stationary and transportation-related sources.

4 Are there acids in the air? We use the pH scale to describe the strength of an acid. The scale is a numerical one from 0 to 14. Pure rain has a pH of about 5.6 while distilled water a pH of 7, which is neutral. Acid rain is defined as precipitation which has a pH of below 5.6. Unit 8 Acid rain, smog and global warming ACID RAIN Battery acid AcidicBasic Pure rain (5.6) Distilled water Ammonia Neutral

5 Areas most affected by acid rain Unit 8 Acid rain, smog and global warming km Areas most affected by acid rain Indian Ocean Pacific Ocean Atlantic Ocean Arctic Ocean Australasia AsiaEurope Africa North America South America N

6 How acid rain is formed? Unit 8 Acid rain, smog and global warming Sulphur dioxide Nitrogen oxides Power station Factory Motor vehicle Acid rain Moisture + sulphur dioxide + nitrogen oxides

7 Are there acids in the air? Unit 8 Acid rain, smog and global warming Acid rain affects industrial areas and the neighbouring regions around them. Buildings and statues are damaged

8 Are there acids in the air? Acid rain affects farming and forested areas. Unit 8 Acid rain, smog and global warming Trees are particularly sensitive to acid rain. The acid deposition weakens the trees and affects their nutrient uptake.

9 Effects of acid rain Unit 8 Acid rain, smog and global warming Air pollution creates acid rain Air pollution usually forms high in the clouds Streams are polluted by acid rain Animals and fishes are seriously affected

10 Acid rain in China Unit 8 Acid rain, smog and global warming These provinces lose about $ 3.7 billion worth of farm products annually because of acid rain. 40% of the area of China is now affected by acid rain. More than 1.28 million hectares of forest are also affected. Jiangsu, Zhejiang and five other coastal provinces are the most seriously affected area.

11 What is smog? Smog is a layer of brown haze covering a city caused by pollutants reacting with sunlight. Unit 8 Acid rain, smog and global warming Pollutants such as hydrocarbons, dust, smoke, nitrogen dioxide and ozone react with sunlight to give air a hazy appearance. Smog

12 What is smog? A city with a large population, a lot of factories, thousands of motor vehicles, light winds and plenty sunshine is ideal for the formation of smog. Unit 8 Acid rain, smog and global warming

13 How smog is formed? Sunlight Gases, dust, smoke Gases Motor vehicle Still air Ozone Power station Factory Unit 8 Acid rain, smog and global warming

14 What is smog? Unit 8 Acid rain, smog and global warming Los Angeles on the western coast of USA is seriously affected by smog.

15 What is smog? Unit 8 Acid rain, smog and global warming New York City on the eastern coast of USA and other big cities are also affected by smog. Santiago Sydney

16 Exhaust gas from vehicles on a windless day is the main cause of the formation of smog in Hong Kong. What is smog? Unit 8 Acid rain, smog and global warming China is also seriously affected by smog, especially in those big cities.

17 What is ozone? Ozone ( O 3 ) is a gas made up of oxygen. It is a pollutant gas which has a sharp smell. Unit 8 Acid rain, smog and global warming How ozone is formed? It is formed when sunlight or lightning strikes oxygen. Sunlight Ozone Nitrogen dioxide It is formed when nitrogen dioxide reacts with sunlight. Lightning OxygenOzone

18 What is global warming? Unit 8 Acid rain, smog and global warming Carbon dioxide 60% Water vapour 8% CFCs 12% 5% Nitrogen oxides Methane 15% The major greenhouse gases Greenhouse gases There are gases in the atmosphere which trap heat and keep the earths surface warm. Most of the greenhouse gases have increased rapidly in quantity in the atmosphere except water vapour.

19 Greenhouse gases Unit 8 Acid rain, smog and global warming Carbon dioxide and nitrogen oxides are produced in the burning of fossil fuels. Methane is produced in rice farming and cattle rearing.

20 Things that give off CFCs CFCs are used as coolants in air-conditioners, refrigerators and as aerosol propellants. Unit 8 Acid rain, smog and global warming Air-conditioner Computer Spray can Refrigerator Motor vehicle Fast food plastic foam container

21 What is global warming? Unit 8 Acid rain, smog and global warming Sun Sunlight Earth surface Heat reflected back to Earths surface Water vapour, carbon dioxide, methane, nitrogen oxides, CFCs Greenhouse gases trap heat The heat-trapping process the greenhouse effect has resulted in a rise in world temperature -- global warming.

22 What is global warming? Ozone hole The ozone layer protects us from ultraviolet radiation from the sun. Too much ultraviolet radiation causes cancer in people and animals. Unit 8 Acid rain, smog and global warming

23 The hole in the Antarctic Since the late 1970s, scientists have found that ozone in the atmosphere above the Antarctic has been decreasing. The layer of ozone above it becomes so thin that a hole develops over the continent. The percentage of ozone in the Antarctic ozone layer is rapidly declining. Unit 8 Acid rain, smog and global warming

24 Terms to learn Acid rain Acid rain ( ) -- rain that is acidic because it has mixed with acidic gases sulphur oxides and nitrogen oxides. It has a pH of below 5.6. Smog Smog ( ) -- a layer of brown haze covering a city caused by pollutants reacting with sunlight. Greenhouse effect Greenhouse effect ( ) -- the process in which greenhouse gases trap suns heat, leading to the rise in world temperature. Global warming Global warming ( ) -- the rise in world temperature as a result of the greenhouse effect. Unit 8 Acid rain, smog and global warming


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