Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

Unit 4A Gases in the Atmosphere

VIEWS: 8 PAGES: 9

									Unit 4A: Gases in the
    Atmosphere
Section A.1 – Structure of the
        Atmosphere



                                 1
• Most of the atmosphere’s mass and all of its
  weather are located within 10-15 km of
  Earth’s surface.




• This is a very small distance compared to the
  size of the Earth.

                                                  2
               The Troposphere
• If Earth were roughly the size of a basketball, the
  portion of the atmosphere called the troposphere
  would be relatively thinner than the basketball’s
  pebbled textured surface.
• Gases mix continuously in the troposphere
   – Its composition is relatively uniform around the world
• The word troposphere is based on the Greek
  words tropos, which means turn, and sphaira,
  which means sphere.
                                                              3
               COMPONENTS OF DRY TROPOSPHERIC AIR
   Substance                Formula             Percent of All Gas
                                                   Molecules
Major Components
    Nitrogen                   N2                     78.08
     Oxygen                    O2                     20.95
Minor Components
      Argon                    Ar                      0.93
 Carbon Dioxide               CO2                     0.033
Trace Components
       Neon                   Ne                     0.0018
    Ammonia                   NH3                    0.0010
      Helium                  He                     0.0005
     Methane                  CH4                    0.0002
     Krypton                   Kr                    0.0001




                                                                     4
• Chemical analysis reveals that ancient air trapped
  in glacial ice has about the same chemical
  makeup as does our current atmosphere




• This finding suggests that there has been little
  change, except for CO2 concentrations in
  tropospheric air over a very long time
                                                     5
• Air is a mixture of gases (see table on Slide 4)
  – Nitrogen is most abundant
  – Oxygen second most abundant
• Air samples can also contain up to 5% water
  vapor
  – Most locations water vapor is 1-3%
  – The amount of water vapor in the air determines
    its humidity




                                                      6
• Other gases naturally present in air at
  concentrations below 0.0001% (1ppm):
  –   Hydrogen
  –   Xenon
  –   Ozone (O3)
  –   Nitrogen oxides (NO and NO2)
  –   Carbon monoxide
  –   Sulfur dioxide
• Human activity and natural phenomena, such as
  volcanic eruptions, can alter the concentrations
  of some trace gases and add other substances to
  air

                                                     7
    The Atmosphere from Space
• The only components of the atmosphere
  visible from space are condensed water vapor
  in the form of clouds and, at times, traces of
  colored nitrogen oxides (Nox) pollutants near
  urban areas.
• Section 4.2 (in class graphing activity) will
  provide information about changes in
  pressure, temperature, and mass of air as you
  head from Earth out toward space.

                                                   8
         HOMEWORK QUESTIONS
• Refer to this PowerPoint and the 4.2 graphing activity from
  class to answer the following:
1) List the percent values of the four most plentiful gases
    found in the atmosphere.
2) Is the mixture of gases in the atmosphere considered a
    solution, a suspension, or a colloid? Explain your answer.
3) Sketch and label the four layers of the atmosphere.
    Account for relative sizes.
4) A. Has the atmosphere’s composition significantly
    changed throughout human history?
    B. What evidence can you cite to support your answer?
5) List three changes in the atmosphere as altitude increases
    from sea level upward.

                                                             9

								
To top