Each statement represents the primary learning objective for the corresponding section heading within this chapter.  After you complete this chapter, you should be able to:

• Distinguish between weather and climate, name the basic elements of weather and climate, and list several important atmospheric hazards (Section 1.1).
  
  

• Discuss the nature of scientific inquiry, including the construction of hypotheses and the development of theories (Section 1.2).
  
  

• List and describe Earth’s four major spheres. Define system, and explain why Earth is considered a system (Section 1.3).
  
  

• List the major gases composing Earth’s atmosphere and identify the components that are most important meteorologically (Section 1.4).
  
  

• Interpret a graph that shows changes in air pressure from Earth’s surface to the top of the atmosphere. Sketch and label a graph that shows the thermal structure of the atmosphere (Section 1.5).

Earth’s atmosphere is unique. No other planet in our solar system has an atmosphere with the exact mixture of gases or the heat and moisture conditions necessary to sustain life as we know it. The gases that make up Earth’s atmosphere and the controls to which they are subject are vital to our existence. In this chapter we begin our examination of the ocean of air in which we all must live. 

Focus on the Atmosphere

• Weather in the United States

• Meteorology, Weather, and Climate

• Atmospheric Hazards

The Nature of Scientific Inquiry

• Hypothesis

• Theory

• Scientific Inquiry

Earth as a System

• Earth's Spheres

  • The Atmosphere

  • The Hydrosphere

  • The Lithosphere

  • The Biosphere

• The Earth System

  • Earth as a System

  • What Powers the Earth System?

Composition of the Atmosphere

• Nonvariable Components

• Variable Components

  • Carbon Dioxide

  • Water Vapor

  • Aerosols

  • Ozone

Vertical Structure of the Atmosphere

• Pressure Changes

• Temperature Changes

• Troposphere

• Stratosphere

• Mesosphere

• Thermosphere

• The Ionosphere