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Unit 8 Acid rain, smog and global warming. Unit 8. Acid rain, smog and global warming. Sulphur dioxide. . H 2 O. Nitrogen oxides. . H 2 O. Unit 8 Acid rain, smog and global warming. Are there acids in the air?.

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unit 8

Unit 8 Acid rain, smog and global warming

Unit 8

Acid rain, smog and global warming

are there acids in the air

Sulphur dioxide

H2O

Nitrogen oxides

H2O

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.

Sulphuric acid

Nitrogen oxides are emitted from both stationary and transportation-related sources.

Nitric acid

are there acids in the air1

Battery acid

Pure rain (5.6)

Distilled water

Ammonia

ACID RAIN

Acidic

Neutral

Basic

Unit 8 Acid rain, smog and global warming

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.

areas most affected by acid rain

N

Arctic Ocean

North America

Europe

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

Areas most affected by acid rain
how acid rain is formed

Sulphur dioxide

Moisture + sulphur dioxide + nitrogen oxides

Nitrogen oxides

Acid rain

Motor vehicle

Factory

Power station

Unit 8 Acid rain, smog and global warming

How acid rain is formed?
are there acids in the air2

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

are there acids in the air3

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

Are there acids in the air?

Acid rain affects farming and forested areas.

effects of acid rain

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

Streams are polluted by acid rain

Animals and fishes are seriously affected

acid rain in china

Unit 8 Acid rain, smog and global warming

Acid rain in China

40% of the area of China is now affected by acid rain.

Jiangsu, Zhejiang and five other coastal provinces are the most seriously affected area.

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.

what is smog

Smog

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.

what is smog1

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.

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

How smog is formed?
what is smog2

Los Angeles on the western coast of USA is seriously affected by smog.

Unit 8 Acid rain, smog and global warming

What is smog?
what is smog3

Sydney

Santiago

Unit 8 Acid rain, smog and global warming

What is smog?

New York City on the eastern coast of USA and other big cities are also affected by smog.

what is smog4

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.

what is ozone

It is formed when sunlight or lightning strikes oxygen.

It is formed when nitrogen dioxide reacts with sunlight.

Sunlight

Ozone

Lightning

Nitrogen dioxide

Oxygen

Ozone

Unit 8 Acid rain, smog and global warming

What is ozone?

Ozone (O3) is a gas made up of oxygen. It is a pollutant gas which has a sharp smell.

How ozone is formed?

what is global warming

Water vapour 8%

CFCs 12%

5%

Nitrogen oxides

Carbon dioxide 60%

Methane 15%

The major greenhouse gases

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.

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.

things that give off cfcs

Spray can

Air-conditioner

Fast food plastic foam container

Computer

Motor vehicle

Refrigerator

Unit 8 Acid rain, smog and global warming

Things that give off CFCs

CFCs are used as coolants in air-conditioners, refrigerators and as aerosol propellants.

what is global warming1

Sun

Water vapour, carbon dioxide, methane, nitrogen oxides, CFCs

Greenhouse gases trap heat

Sunlight

Heat reflected back to Earth’s surface

Earth surface

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.

what is global warming2

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.

the hole in the antarctic

Unit 8 Acid rain, smog and global warming

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.

terms to learn

Unit 8 Acid rain, smog and global warming

Terms to learn

Acid rain (酸雨)-- 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 (煙霧)-- a layer of brown haze covering a city caused by pollutants reacting with sunlight.

Greenhouse effect (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)-- the rise in world temperature as a result of the greenhouse effect.