Portrait of the Atmosphere

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Chapter Outline

  • 1.1

    Composition of the Atmosphere

  • 1.2

    The Weight of Air: Atmospheric Pressure

  • 1.3

    The Layered Atmosphere

  • 1.4

    Air Pollution

  • 1.5

    Geographic Perspectives: Refrigerators and Life on Earth
This photo shows lenticular clouds that have formed over the mountains in South Georgia, a British overseas territory in the South Atlantic Ocean. The atmosphere’s clouds and precipitation occur almost exclusively within the lowest layer of the atmosphere.
(© Andy Rouse/naturepl.com/NaturePL)

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LIVING PHYSICAL GEOGRAPHY

  • What are clouds made of?

  • How high does the atmosphere go?

  • What are northern lights?

  • Why are skin cancer rates increasing worldwide?

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THE BIG PICTURE

The atmosphere is composed of gases and has a layered structure. It shields us from the Sun’s harmful rays, but human activity has changed the atmosphere’s protective shield.

LEARNING GOALS

After reading this chapter, you will be able to:

  • 1.1

    Describe the gases and other materials that make up the atmosphere.

  • 1.2

    Explain what causes air pressure and how air pressure changes vertically within the atmosphere.

  • 1.3

    Name and describe the atmosphere’s layers.

  • 1.4

    Identify major atmospheric pollutant types and discuss their effects on human health.

  • 1.5

    Assess the effects of anthropogenic pollutants in the ozonosphere and the anticipated condition of the ozonosphere in the coming decades.

THE HUMAN SPHERE:

Wyoming’s Air Pollution Problem

FOR MANY, WYOMING BRINGS to mind clean skies as far as the eye can see. But lately, western Wyoming’s ground-level ozone pollution has at times rivaled that found in Los Angeles or Houston, two of the smoggiest cities in the nation.

The United States is currently experiencing a boom in drilling for natural gas. Wyoming and many other states have both prospered from and suffered the consequences of a rush to extract natural gas from the ground (Figure 1.1).

Figure 1.1

Natural gas wells. Extraction of natural gas has brought economic prosperity and jobs to Wyoming, but it has also brought poor air quality. Excess natural gas that escapes from the ground is wasted as it is burned (or flared) off at this drilling rig in the Jonah Field near Pinedale, Wyoming.
(Joel Sartore/NationalGeographic/Getty Images)

Extracting natural gas from the ground is energy intensive and requires diesel-fueled machinery that pollutes the air. In addition, natural gas leaks from the wells. A 2012 study found that up to 9% of the gas extracted may leak directly into the atmosphere. This leakage, along with the exhaust from machinery, is resulting in significant ground-level pollution, including ozone pollution. The wells are also suspected of causing contamination of drinking water in the ground.

This chapter explores the composition of the atmosphere, air pressure in the atmosphere, the layered structure of the atmosphere, and air pollution. The protective role of the atmosphere is also examined in light of the effects of CFCs (chlorofluorocarbons), gases released into the atmosphere by human activities.

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