Lesson 1A: Composition and Structure of the Atmosphere

Estimated Time: Three forty-five minute class periods.

Indicator(s) Core Learning Goal 1:
1.5.4 The student will create and/or interpret graphics (scale drawings, photographs, digital images, etc.).
1.5.9 The student will communicate conclusions derived through a synthesis of ideas.

Indicator(s): Core Learning Goal 2:
2.2.2. The student will explain the role of natural forces in the earth.
At least – retention of an atmosphere, an agent of erosion and deposition, tides and deep ocean currents
2.3.1. The student will describe heat transfer systems in the atmosphere, on land, and in the oceans.
At least – convection, conduction, radiation from space and from within Earth

Student Outcome(s):
1. The student will be able to represent the vertical features of the atmosphere by applying scale to design a poster.
2. The student will be able to relate gravity, pressure, gas composition, altitude, and the layers of the atmosphere by constructing a systems diagram or concept map.

Brief Description:

This lesson allows the student to develop an understanding of a relative sense of the vertical dimensions of the atmosphere and provides background information that will be used in later lessons, especially the lesson on barometric pressure and the lesson on ozone depletion.

Students will use pressure data to generate a graph of pressure change with increasing altitude. Students will use the graph and knowledge of gravity to deduce where the majority of the air in the atmosphere is located. Students will develop a poster that displays various atmospheric features according to vertical scale. Finally, students will relate gravity, pressure, gas composition, altitude, and the layers of the atmosphere by constructing a systems diagram or concept map.

Background knowledge / teacher notes:

After plotting the pressure data students should recognize that barometric pressure drops gradually with increasing altitude in the lower and middle troposphere but drops very rapidly with increased altitude in layers above the troposphere. Gravity is the natural force that retains the Earth's atmosphere. Since barometric pressure is the weight of air, students should be able to conclude that most of the air in the atmosphere is located in the lower to middle portions of the troposphere.

The atmosphere is divided up into layers based on temperature characteristics. Most references will refer to the layers as troposphere, stratosphere, mesosphere and the thermosphere. Students may also come across the term ionosphere. Ionosphere is a term that combines the mesosphere and the thermosphere into one layer consisting of charged particles (ions). The boundaries between the layers are the tropopause, the stratopause and the mesopause.

The troposphere is composed of (not counting water vapor which varies significantly) 78% nitrogen (N2) 21% oxygen (O2) The remaining one percent is composed of mainly argon and carbon dioxide. The stratosphere (the location of the ozone layer) is mostly composed of ozone (O3) and the mesosphere and the thermosphere contains concentrations of nitrogen and oxygen ions.

Temperatures decrease with altitude in the troposphere, increase in the stratosphere, decrease in the mesosphere and then increase in the thermosphere. All clouds are located at various altitudes in the troposphere. The peak of Mount Everest is at about 8000 meters, which is about two thousand meters below the tropopause. Commercial airlines fly in a range of altitudes the highest of which are located high above the clouds in the Stratosphere.

Lesson Description:

ENGAGE

Ask students to consider questions, such as

  • What holds air close to Earth?
  • Why do jet fighter pilots where air masks?
  • Why are commercial airplane cockpits pressurized?

Remind students that the atmosphere is made up of several layers and that the storms discussed earlier only occur in the lowest layer of the atmosphere.

EXPLORE

  1. Students graph the data in the chart, Barometric Pressures and Altitude. Students should label specific features on the graph: layers of the atmosphere (troposphere, stratosphere, mesosphere and the thermosphere), the peak of Mt. Everest (8,000 m), and the height at which commercial airplanes fly (above the clouds of the stratosphere).
  2. Based on the fact that barometric pressure is the weight of air, ask students to hypothesize where most of the air in the atmosphere is located (in the lower to middle portions of the troposphere).
  3. Ask students to research the following additional data:
  • the four layers of the atmosphere
  • the boundaries between the layers
  • the major gases in each atmosphere
  • the temperature changes that occur in each layer
  • the location within the atmosphere of major cloud types (including but not limited to stratus clouds, cumulonimbus clouds, alto clouds and cirrus clouds)
  • the peak of Mount Everest
  • the ozone layer
  • the altitudes at which commercial airliners fly.

Accommodations: Provide n organizer for students to use to record research data.

Use of Expert Groups (cooperative learning structure) could limit the amount of research each student must complete.

Education Elements:

BACKGROUND INFORMATION

Excellent and vast information on the atmosphere — available in three ability levels

http://windows.arc.nasa.gov/cgibin/tour.cgi?link=/earth/Atmosphere/overview.html&art=ok&cdp=/windows3.html&cd=false&frp=/windows3.html&fr=f&sw=false&edu=mid

SCIENTIFIC TOOLS

SEES figure 1.02 — graph of Atmospheric layers

http://see.gsfc.nasa.gov/edu/SEES/globa/class/Chap_1/1_Js/1-02.jpg

 

Using the information and data collected in the exploration, ask students to design a poster which demonstrates the vertical scale of the atmosphere and the features listed above. Before students begin, ask the class to design a scoring tool or checklist for evaluating the poster. After completing the poster, each group should pair up with another group and go through a mock presentation and peer review process. (DOL3)

EXTEND

Journal Write: Describe the way gas volumes (the amount of gases) and pressure changes in each layer of the atmosphere.

Ask students to complete a systems diagram or concept map that will show the relationships between gravity, pressure, gas composition, altitude, and the layers of the atmosphere.

Accommodation: Provide a frame paragraph or sentences starters for individual students as needed.

EVALUATE

After class discussion students will evaluate their extension paragraph and diagrams for accuracy and validity.

Journal Write: Students will write a follow up statement that discusses how their ideas discussed in their extension paragraph changed following the class discussion.

EXTEND

Career Connection:

A TYPICAL DAY IN THE LIFE OF A NATIONAL WEATHER SERVICE EMPLOYEE.

National Weather Service. Available:

http://www.nws.noaa.gov/er/phi/tour/gary.html

Modification: Career Connection may need to be eliminated for students who need more time for research, construction of the poster, or paragraph writing.

Materials:

Pressure changes with altitude data sheet

Graph paper

Poster board or newsprint

Markers or colored pencils

Resource Books

Computers with Internet access

Resources:

THE ATMOSPHERE.

National Weather Service. Available:

http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/ATM_CHEM/atmospheric_structure.html

A TYPICAL DAY IN THE LIFE OF A NATIONAL WEATHER SERVICE EMPLOYEE.

National Weather Service. Available:

http://www.nws.noaa.gov/er/phi/tour/gary.html

 

Barometric Pressures and Altitude

 

Altitude

(Kilometers)

Average Barometric Pressure

(Millibars)

0

1000

2

800

6

425

10

275

14

150

18

100

22

50

26

30

30

25

36

25