Unit 8 Acid rain smog and global warming

Unit 8 Acid rain, smog and global warming

Unit 8 Acid rain, smog and global warming Are there acids in the air? Acid rain is also called “acid precipitation” (snow, rain, fog, and dry particulate acidic depositions). Sulphur dioxide is emitted primarily from stationary sources such as power plants that burn fossil fuels. Sulphur dioxide H 2 O Sulphuric acid Nitrogen oxides are emitted from both stationary and transportation-related sources. Nitrogen oxides H 2 O Nitric acid

Unit 8 Acid rain, smog and global warming Are there acids in the air? We use the p. H scale to describe the strength of an acid. The scale is a numerical one from 0 to 14. Battery acid Pure rain (5. 6) Distilled water Ammonia ACID RAIN Acidic Neutral Basic Pure rain has a p. H of about 5. 6 while distilled water a p. H of 7, which is neutral. Acid rain is defined as precipitation which has a p. H of below 5. 6.

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

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

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

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

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

Unit 8 Acid rain, smog and global warming Acid rain in China 40% of the area of China is now affected by acid rain. These provinces lose about $3. 7 billion worth of farm products annually because of 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.

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

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

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

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

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

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

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

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

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

Unit 8 Acid rain, smog and global warming What is global warming? The heat-trapping process the “greenhouse effect” has resulted in a rise in world temperature -- global warming. Greenhouse gases trap heat Sun ligh t Water vapour, carbon dioxide, methane, nitrogen oxides, CFCs Heat reflected back to Earth’s surface Earth surface Sun

Unit 8 Acid rain, smog and global warming 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 The “hole” in the Antarctic Since the late 1970 s, 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 Terms to learn Acid rain (酸雨) 酸雨 -- rain that is acidic because it has mixed with acidic gases sulphur oxides and nitrogen oxides. It has a p. H of below 5. 6. Smog (煙霧) 煙霧 -- a layer of brown haze covering a city caused by pollutants reacting with sunlight. Greenhouse effect (溫室效應) 溫室效應 -- the process in which greenhouse gases trap sun’s heat, leading to the rise in world temperature. Global warming (全球增溫) 全球增溫 -- the rise in world temperature as a result of the greenhouse effect.