Unit 4 Lesson 3 Human Impact on the Atmosphere

Air: What Is It Good For? Why is the atmosphere important? Unit 4 Lesson 3 Human Impact on the Atmosphere Air: What Is It Good For? Why is the atmosphere important? Air is an important natural resource. The air you breathe forms part of Earth’s atmosphere. The atmosphere is a mixture of gases that surrounds Earth. 2

Why is the atmosphere important? Unit 4 Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? The atmosphere provides gases that organisms need to survive, including oxygen and carbon dioxide. The atmosphere blocks harmful, high-energy radiation coming from space. Fast-moving particles, called cosmic rays, enter the atmosphere every second. They collide with various gas molecules and are slowed down. 3

Why is the atmosphere important? Unit 4 Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? A part of the atmosphere called the stratosphere contains ozone gas (O₃). The ozone layer absorbs most of the high-energy radiation from the sun, called ultraviolet radiation (UV), that reaches Earth. 4

Why is the atmosphere important? Unit 4 Lesson 3 Human Impact on the Atmosphere Why is the atmosphere important? Without the atmosphere, temperatures on Earth would not be stable, and it would be too cold for life to exist. The greenhouse effect is the way by which certain gases in the atmosphere, such as water vapor and carbon dioxide, absorb and reradiate thermal energy. Carbon dioxide and water vapor are called greenhouse gases. 6

Unit 4 Lesson 3 Human Impact on the Atmosphere What is air pollution? The contamination of the atmosphere by pollutants from human and natural sources is called air pollution. Air pollution can come from natural sources, such as volcanic eruptions, wildfires, and dust storms. In cities and suburbs, most air pollution comes from the burning of fossil fuels. 8

Unit 4 Lesson 3 Human Impact on the Atmosphere What is air pollution? Some air pollutants are classified as gases, such as carbon monoxide, sulfur dioxide, nitrogen oxide, and ground-level ozone. Other air pollutants are classified as particulates. A particulate is a tiny solid particle that is suspended in air or water. The particulates from vehicle exhaust are a major cause of air pollution in cities. 9

It Stinks! What pollutants can form from vehicle exhaust? Unit 4 Lesson 3 Human Impact on the Atmosphere It Stinks! What pollutants can form from vehicle exhaust? Vehicle exhaust is a common source of air pollution in urban areas. Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air. Although ozone in the ozone layer is necessary for life, ground-level ozone can damage the lungs. 11

What pollutants can form from vehicle exhaust? Unit 4 Lesson 3 Human Impact on the Atmosphere What pollutants can form from vehicle exhaust? Smog is another type of pollutant formed from vehicle exhaust. Smog forms when ground-level ozone and vehicle exhaust react in the presence of sunlight. Smog can cause lung damage and irritate the eyes and nose. In some cities, there is enough smog to make a brownish haze over the city. 12

How does pollution from human activities produce acid precipitation? Unit 4 Lesson 3 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? Precipitation such as rain, sleet, or snow that contains acids from air pollution is called acid precipitation. Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air. When these gases mix with water in the atmosphere, they form sulfuric acid and nitric acid. 14

How does pollution from human activities produce acid precipitation? Unit 4 Lesson 3 Human Impact on the Atmosphere How does pollution from human activities produce acid precipitation? Sulfuric acid and nitric acid are strong acids. They can make precipitation so acidic that it is harmful to the environment. 15

What are some effects of acid precipitation? Unit 4 Lesson 3 Human Impact on the Atmosphere What are some effects of acid precipitation? Acid precipitation can cause soil and water to become more acidic than normal. An increase in soil acidity can cause the soil to lose some of the nutrients that plants need. Bacteria and fungi in the soil are also harmed by acidic conditions. 16

What are some effects of acid precipitation? Unit 4 Lesson 3 Human Impact on the Atmosphere What are some effects of acid precipitation? Acid precipitation can also make lakes and streams more acidic and cause soils to release toxic metals into the water. These changes can harm aquatic organisms, disrupt habitats, and decrease the biodiversity of an ecosystem. Acid precipitation can also erode the stonework on buildings and statues. 17

How’s the Air? What are measures of air quality? Unit 4 Lesson 3 Human Impact on the Atmosphere How’s the Air? What are measures of air quality? Measuring how clean or polluted the air is tells us about air quality. As pollution increases, air quality decreases. Two major threats to air quality are vehicle exhausts and industrial pollutants. 18

What are measures of air quality? Unit 4 Lesson 3 Human Impact on the Atmosphere What are measures of air quality? The Air Quality Index (AQI) is a number used to describe the air quality of a location. The higher the AQI number, the more people are likely to have health problems linked to air pollution. The air inside a building can become more polluted than the air outside. Ventilation, or the mixing of indoor and outside air, can reduce indoor air pollution. 20

What are measures of air quality? Unit 4 Lesson 3 Human Impact on the Atmosphere What are measures of air quality? What are some sources of indoor air pollution? 21

How can air quality affect health? Unit 4 Lesson 3 Human Impact on the Atmosphere How can air quality affect health? Daily exposure to small amounts of air pollution can cause serious health problems. Children, elderly people, and people with health problems are especially vulnerable to the effects of air pollution. Short-term effects include coughing, headaches, and wheezing. Long-term effects include lung cancer and emphysema, which can cause death. 22

Things are Changing How might humans be changing Earth’s climates? Unit 4 Lesson 3 Human Impact on the Atmosphere Things are Changing How might humans be changing Earth’s climates? As a result of burning fossil fuels, the atmosphere today contains about 37 percent more carbon dioxide than it did in the mid-1700s. Average global temperatures have also risen in recent decades. 23

How might humans be changing Earth’s climate? Unit 4 Lesson 3 Human Impact on the Atmosphere How might humans be changing Earth’s climate? It is hard to know exactly how much the extra greenhouse gases change the temperature. Computer models designed to understand climate change predict that average global temperatures will continue rising. 24

What are some predicted effects of climate change? Unit 4 Lesson 3 Human Impact on the Atmosphere What are some predicted effects of climate change? Many changes on Earth have already been linked to higher temperatures. A warmer Earth may lead to changes in rainfall patterns, rising sea levels, and more severe storms. Such changes will likely have negative effects for life on Earth, as well as political and economic effects. 25

How is the ozone layer affected by air pollution? Unit 4 Lesson 3 Human Impact on the Atmosphere How is the ozone layer affected by air pollution? Earth’s protective ozone layer is thinning over the polar regions, allowing more harmful ultraviolet radiation to reach Earth’s surface. Chemicals called chlorofluorocarbons (CFCs) cause ozone to break down. CFCs once had many industrial uses, but now they are banned. However, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone. 26